PROBUSINESS SERVICES INC
S-1, 1998-08-05
COMPUTER PROCESSING & DATA PREPARATION
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<PAGE>
     AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON AUGUST 5, 1998
 
                                                   REGISTRATION NO. 333-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                           --------------------------
                                    FORM S-1
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------
                           PROBUSINESS SERVICES, INC.
             (Exact name of Registrant as specified in its charter)
                           --------------------------
 
<TABLE>
<S>                               <C>                               <C>
            DELAWARE                            7374                           94-2976066
(State or other jurisdiction of     (Primary Standard Industrial            (I.R.S. Employer
         incorporation)             Classification Code Number)          Identification Number)
</TABLE>
 
                               4125 HOPYARD ROAD
                              PLEASANTON, CA 94588
                                 (925) 737-3500
 
         (Address, including zip code, and telephone number, including
            area code, of Registrant's principal executive offices)
                           --------------------------
                                THOMAS H. SINTON
                     PRESIDENT AND CHIEF EXECUTIVE OFFICER
                               4125 HOPYARD ROAD
                              PLEASANTON, CA 94588
                                 (925) 737-3500
           (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)
                           --------------------------
 
                                   COPIES TO:
 
<TABLE>
<S>                                         <C>
              ALAN K. AUSTIN                           KENNETH L. GUERNSEY
            ELIZABETH R. FLINT                            KARYN R. SMITH
               BRIAN C. ERB                            MICHAEL W. HAUPTMAN
             JOHN L. WHITTLE                            COOLEY GODWARD LLP
          MARY ELIZABETH SHANNON                        ONE MARITIME PLAZA
     WILSON SONSINI GOODRICH & ROSATI                       20TH FLOOR
         PROFESSIONAL CORPORATION                    SAN FRANCISCO, CA 94111
            650 PAGE MILL ROAD                            (415) 693-2000
           PALO ALTO, CA 94304
              (650) 493-9300
</TABLE>
 
                           --------------------------
 
        APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC:
As soon as practicable after the effective date of this Registration Statement.
 
    If any of the securities being registered on this Form are to be offered on
a delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, as amended, check the following box. / /
 
    If this form is filed to register additional securities for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. / /
 
    If this form is a post-effective amendment filed pursuant to Rule 462(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. / /
 
    If delivery of the Prospectus is expected to be made pursuant to Rule 434,
please check the following box. / /
                            ------------------------
 
                        CALCULATION OF REGISTRATION FEE
 
<TABLE>
<CAPTION>
                                                              PROPOSED MAXIMUM AGGREGATE
    TITLE OF EACH CLASS OF SECURITIES TO BE REGISTERED          OFFERING PRICE (1)(2)         AMOUNT OF REGISTRATION FEE
<S>                                                         <C>                             <C>
Common Stock, par value $0.001 per share..................           $110,000,000                      $32,450
</TABLE>
 
(1) Includes the aggregate offering price of shares which the Underwriters have
    the option to purchase to cover over-allotments, if any.
 
(2) Estimated solely for the purpose of computing the amount of the registration
    fee pursuant to rule 457(o) promulgated under the Securities Act of 1933, as
    amended.
                         ------------------------------
 
    THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL
FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(a) OF
THE SECURITIES ACT OF 1933, AS AMENDED, OR UNTIL THE REGISTRATION STATEMENT
SHALL BECOME EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION,
ACTING PURSUANT TO SAID SECTION 8(a), MAY DETERMINE.
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
Information contained herein is subject to completion or amendment. A
registration statement relating to these securities has been filed with the
Securities and Exchange Commission. These securities may not be sold nor may
offers to buy be accepted prior to the time the registration statement becomes
effective. This Prospectus shall not constitute an offer to sell or the
solicitation of an offer to buy nor shall there be any sale of these securities
in any State in which such offer, solicitation or sale would be unlawful prior
to registration or qualification under the securities laws of any such State.
<PAGE>
                  SUBJECT TO COMPLETION, DATED AUGUST 5, 1998
 
PROSPECTUS
 
                                2,475,000 SHARES
 
                                     [LOGO]
 
                                  COMMON STOCK
 
    All of the 2,475,000 shares of Common Stock offered hereby are being sold by
ProBusiness Services, Inc. ("ProBusiness" or the "Company").
 
    The Company has declared a 3-for-2 stock split in the form of a stock
dividend, to be paid on August 7, 1998 to holders of record on July 31, 1998.
All share and per share information in this Prospectus has been adjusted to
reflect this stock split.
 
    The Common Stock offered hereby is quoted on the Nasdaq National Market
under the symbol "PRBZ." On August 4, 1998, the last reported sale price of the
Common Stock was $52.75 (equivalent to $35.167 after giving effect to the stock
split). See "Price Range of Common Stock."
 
    SEE "RISK FACTORS" BEGINNING ON PAGE 5 FOR A DISCUSSION OF CERTAIN FACTORS
THAT SHOULD BE CONSIDERED BY PROSPECTIVE PURCHASERS OF THE SHARES OF COMMON
STOCK OFFERED HEREBY.
                            ------------------------
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
    EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION NOR HAS THE
       SECURITIES AND EXCHANGE COMMISSION OR ANY STATE SECURITIES
            COMMISSION PASSED UPON THE ACCURACY OR ADEQUACY OF
                THIS PROSPECTUS. ANY REPRESENTATION TO THE
                           CONTRARY IS A CRIMINAL OFFENSE.
 
<TABLE>
<CAPTION>
                                                             UNDERWRITING      PROCEEDS TO
                                           PRICE TO PUBLIC    DISCOUNT(1)      COMPANY(2)
<S>                                        <C>              <C>              <C>
Per Share................................         $                $                $
Total(3).................................         $                $                $
</TABLE>
 
(1) The Company has agreed to indemnify the Underwriters against certain
    liabilities, including liabilities under the Securities Act of 1933, as
    amended. See "Underwriting."
 
(2) Before deducting expenses payable by the Company estimated at $670,000.
 
(3) The Company has granted to the Underwriters a 30-day option to purchase up
    to an additional 371,250 shares of Common Stock solely to cover
    over-allotments, if any. See "Underwriting." If all such shares are
    purchased, the total Price to Public, Underwriting Discount and Proceeds to
    Company will be $        , $        and $        , respectively.
 
    The Common Stock is offered by the several Underwriters when, as and if
delivered to and accepted by them and subject to their right to reject orders in
whole or in part. It is expected that delivery of the certificates for the
Common Stock will be made on or about            , 1998.
 
WILLIAM BLAIR & COMPANY
 
                            BANCAMERICA ROBERTSON STEPHENS
                                                                        SG COWEN
 
                THE DATE OF THIS PROSPECTUS IS            , 1998
<PAGE>
    The Inside Front Cover of the Prospectus includes text stating, "ProBusiness
is a leading provider of outsourced payroll processing, payroll tax filing and
benefits administration services to large employers." Below the text is an arrow
pointing to the ProBusiness logo at the bottom right side of the page. The
background photo behind the text depicts ProBusiness service personnel assisting
a client.
 
    GATEFOLD:
 
    The Gatefold consists of three horizontal tiers, the top and the middle
containing text and photographs and the bottom containing text related to the
text and photographs in the middle tier. The top tier consists of captions
accompanying the following: the ProBusiness logo, a rectangular collage of
photographs and a rectangle containing client logos. In the background of the
top tier is a photograph of ProBusiness service personnel assisting a client.
The middle tier consists of the words "Business Partnership" at the far left in
italics, then three equal-size rectangular photographs and, at the far right, a
collage of four overlapping rectangular photographs. The middle tier photographs
are connected by downward arrows to corresponding captions, which are in the
bottom tier of the gatefold.
 
    Description #1: Description of the left section of the upper tier of the
gatefold: The ProBusiness logo with text below it stating, "ProBusiness focuses
on providing added value to large employers with its high quality and
cost-effective employee administrative services."
 
    Description #2: Description of the center section of the upper tier of the
gatefold: A collage of photographs depicting various documents and items related
to the services provided by ProBusiness.
 
    Description #3: Description of the right section of the upper tier of the
gatefold: A rectangular containing the logos of the following eight companies:
CCH Incorporated, Advanced Micro Devices, Inc., 3Com Corporation, AST Research,
Inc., Yahoo Inc., Oracle Corporation, Boise Cascade Corporation, First Allmerica
Financial Life Insurance Company and First Data Corporation.
 
    Caption: "ProBusiness's clients include many large employers in diverse
industries." This caption appears below the rectangle containing the clients'
logos in Description #3.
 
    Description #4: Description of the left section of the middle tier of the
gatefold: "Business Partnership."
 
    Caption: "ProBusiness differentiates itself from its competitors by
establishing a business partnership with each client. The Company develops
relationships with each client by assessing payroll processing needs,
reengineering and designing payroll systems and processes and implementing a
cost-effective solution. The Company maintains an ongoing relationship by
providing proactive account management and technical support." This caption
appears below the text described in Description #4.
 
    Description #5: Description of the left corner section of the middle tier of
the gatefold: A rectangular photograph of an account manager of ProBusiness
assisting a client.
 
    Caption: "Client Service--Delivering high quality, responsive and
professional client service is a key competitive advantage of the Company. Each
client works with a personal account manager who serves as the client's
day-to-day contact and is responsible for meeting the client's needs. The
Company believes that its low client-to-account manager ratio is a key factor in
enabling the Company to achieve a high payroll client retention rate." This
caption appears below the photograph in Description #5.
 
    Description #6: Description of the center section of the middle tier of the
gatefold: A rectangular photograph of two employees of the Company using
personal computers in the Company's production facility.
 
    Caption: "Technology--ProBusiness's proprietary PC-based, distributed
architecture is reliable, flexible and scalable. This technology enables the
Company to provide high levels of client service and customized solutions that
can be easily upgraded and integrated with the client's other systems." This
caption appears below the photograph in Description #6.
 
    Description #7: Description of the right center section of the middle tier
of the gatefold: A rectangular photograph of a ProBusiness specialist
diagramming a client's payroll system on a white board.
 
    Caption: "Expertise--ProBusiness delivers technical expertise through
specialists in design, process, implementation and systems integration. The
Company delivers functional and regulatory expertise in payroll, payroll tax and
employee benefits." This caption appears below the photograph in Description #7.
 
    Description #8: Description of the right section of the middle tier of the
gatefold: Rectangular photographs of an account manager assisting a client,
documents and a computer screen, all of which relate to the service offerings
provided by ProBusiness.
 
    Caption: "Comprehensive Solutions--ProBusiness provides employers with a
broad range of employee administrative services: payroll processing; payroll tax
filing, human resources software and employee benefits administration, including
flexible benefits enrollment and processing and COBRA administration, and human
resources software." This caption appears below the photograph in Description 8.
 
                            ------------------------
 
    CERTAIN PERSONS PARTICIPATING IN THIS OFFERING MAY ENGAGE IN TRANSACTIONS
THAT STABILIZE, MAINTAIN OR OTHERWISE AFFECT THE PRICE OF THE COMMON STOCK,
INCLUDING STABILIZING BIDS, SYNDICATE COVERING TRANSACTIONS OR THE IMPOSITION OF
PENALTY BIDS. FOR A DISCUSSION OF THESE ACTIVITIES, SEE "UNDERWRITING."
 
    IN CONNECTION WITH THIS OFFERING, CERTAIN UNDERWRITERS AND SELLING GROUP
MEMBERS MAY ENGAGE IN PASSIVE MARKET MAKING TRANSACTIONS IN THE COMMON STOCK ON
THE NASDAQ NATIONAL MARKET IN ACCORDANCE WITH RULE 103 OF REGULATION M. SEE
"UNDERWRITING."
 
    PROBUSINESS-REGISTERED TRADEMARK- AND THE PROBUSINESS LOGO ARE REGISTERED
TRADEMARKS OF THE COMPANY. BENESPHERE ADMINISTRATORS-TM- AND ENROLLNET-TM- ARE
TRADEMARKS OF THE COMPANY.
<PAGE>
                               PROSPECTUS SUMMARY
 
    THE FOLLOWING SUMMARY IS QUALIFIED IN ITS ENTIRETY BY THE MORE DETAILED
INFORMATION, INCLUDING "RISK FACTORS" AND THE FINANCIAL STATEMENTS AND NOTES
THERETO, APPEARING ELSEWHERE IN THIS PROSPECTUS. EXCEPT AS OTHERWISE INDICATED,
ALL INFORMATION IN THIS PROSPECTUS ASSUMES NO EXERCISE OF THE UNDERWRITERS'
OVER-ALLOTMENT OPTION AND GIVES EFFECT TO THE THREE-FOR-TWO SPLIT OF THE
COMPANY'S COMMON STOCK (THE "STOCK SPLIT") TO BE EFFECTED IN THE FORM OF A STOCK
DIVIDEND PAYABLE ON AUGUST 7, 1998 TO HOLDERS OF RECORD OF THE COMMON STOCK ON
JULY 31, 1998. THIS PROSPECTUS CONTAINS FORWARD-LOOKING STATEMENTS THAT INVOLVE
RISKS AND UNCERTAINTIES. THE COMPANY'S ACTUAL RESULTS COULD DIFFER MATERIALLY
FROM THOSE ANTICIPATED IN THESE FORWARD-LOOKING STATEMENTS AS A RESULT OF
CERTAIN FACTORS, INCLUDING THOSE SET FORTH UNDER "RISK FACTORS" AND ELSEWHERE IN
THIS PROSPECTUS.
 
                                  THE COMPANY
 
    The Company is a leading provider of employee administrative services for
large employers. The Company's primary service offerings are payroll processing,
payroll tax filing, benefits administration, including the enrollment and
processing of flexible benefit plans and COBRA programs, and human resources
software. The Company's proprietary PC-based payroll system offers the
cost-effective benefits of outsourcing and high levels of client service, while
providing the flexibility, control, customization and integration of an in-house
system. As of June 30, 1998, the Company provided services to approximately
1,400 clients and provided payroll processing services to approximately 510
clients with an aggregate of approximately 575,000 employees and an average of
approximately 1,100 employees. In addition to providing tax filing services for
its payroll clients, as of June 30, 1998 the Company provided stand-alone tax
filing services to 72 clients with an aggregate of more than 1.1 million
employees and an average of more than 15,000 employees. For the quarter ended
June 30, 1998, the Company processed 4.3 million checks for the Company's
payroll clients. The Company's clients include: 3Com Corporation, Abbott
Laboratories, Airtouch Communications Inc., Amoco Corporation, Inc., Ascend
Communications, Inc., AST Research, Inc., Coach Leatherwear Co., Inc., Dell
Computer Corporation, E*TRADE Group, Inc., First Data Corporation, The Gap,
Inc., The Gillette Company, J.C. Penney Company, Inc., Kellogg USA Inc., LSI
Logic Corporation, Michaels Stores, Inc., Netscape Communications Corp., Oracle
Corporation, Sunglass Hut International, Inc., Toyota Motor Corporation, U.S.
Bancorp, Watkins-Johnson Company and Williams-Sonoma, Inc.
 
    The demand for outsourcing employee administrative services has grown
significantly and is expected to continue to grow over the next several years.
According to G-2 Research, Inc., third-party payroll processing, payroll tax
filing and benefits administration is expected to generate approximately $3.9
billion in revenue in 1998 and approximately $9.3 billion in revenue in 2003.
Many large businesses have found that outsourcing non-core functions reduces
costs, improves service, quality and efficiency, allows personnel to focus on
core competencies and enhances productivity through access to advanced
technologies. In recent years, payroll processing and benefits administration
have increased in complexity due to continual changes in regulations and
increasingly sophisticated employee benefits plans.
 
    The Company differentiates itself from its competitors through its
proprietary PC-based technology, high quality, responsive and professional
client service and focus on the needs of large employers. ProBusiness develops a
business partnership with each client by assessing each client's payroll
processing needs, reengineering and designing the client's payroll systems and
processes and implementing a value-added and cost-effective solution. The
Company maintains an ongoing relationship with each client using a strategic
team of specialists led by a personal account manager who proactively manages
each client's account and marshals the resources of the team to meet the
client's specific needs. ProBusiness maintains a low client-to-account manager
ratio to offer clients accessible and responsive account management. The Company
believes that its low client-to-account manager ratio and focus on client
service are key factors in enabling the Company to achieve a high payroll client
retention rate, which was approximately 92% for fiscal year 1998.
 
    The Company's objective is to be the premier provider of employee
administrative services for large employers. The Company's strategy to
accomplish this objective includes expanding its client base by increasing its
direct sales force, developing a comprehensive and fully integrated suite of
employee administrative services, offering additional services to existing
clients, pursuing strategic acquisitions, investments and alliances and
extending its technology leadership. The Company is committed to maintaining the
high levels of professional and personal service that it believes have allowed
it to establish a competitive advantage in its industry.
 
                                       3
<PAGE>
                                  THE OFFERING
 
<TABLE>
<S>                                                     <C>
Common Stock Offered by the Company...................  2,475,000 shares
Common Stock to be Outstanding after this Offering....  19,589,855 shares(1)
                                                        For general corporate purposes, including
                                                        capital expenditures and working capital, as
                                                         well as for potential acquisitions. See "Use
                                                         of Proceeds."
Use of Proceeds.......................................
Nasdaq National Market Symbol.........................  PRBZ
</TABLE>
 
                             SUMMARY FINANCIAL DATA
                     (IN THOUSANDS, EXCEPT PER SHARE DATA)
 
<TABLE>
<CAPTION>
                                                                                            YEAR ENDED JUNE 30,
                                                                                      -------------------------------
                                                                                        1996       1997       1998
                                                                                      ---------  ---------  ---------
<S>                                                                                   <C>        <C>        <C>
STATEMENTS OF OPERATIONS DATA:
Revenue.............................................................................  $  13,863  $  27,374  $  46,317
Operating expenses:
  Cost of providing services........................................................      6,435     13,659     23,859
  General and administrative expenses...............................................      2,054      4,282      6,727
  Research and development expenses.................................................      1,257      2,841      4,585
  Client acquisition costs..........................................................      5,388     11,706     17,858
  Acquisition of in-process technology..............................................        711     --         --
                                                                                      ---------  ---------  ---------
Total operating expenses............................................................     15,845     32,488     53,029
                                                                                      ---------  ---------  ---------
Loss from operations................................................................     (1,982)    (5,114)    (6,712)
Interest expense....................................................................       (473)    (1,190)      (557)
Other income........................................................................         69         59        752
                                                                                      ---------  ---------  ---------
Net loss............................................................................  $  (2,386) $  (6,245) $  (6,517)
                                                                                      ---------  ---------  ---------
                                                                                      ---------  ---------  ---------
Historical basic and diluted net loss per share(2)..................................  $   (4.91)
                                                                                      ---------
                                                                                      ---------
Shares used in computing historical basic and diluted net loss per share(2).........        486
Pro forma basic and diluted net loss per share(2)...................................             $   (0.59) $   (0.41)
                                                                                                 ---------  ---------
                                                                                                 ---------  ---------
Shares used in computing pro forma basic and diluted net loss per share(2)..........                10,533     15,722
</TABLE>
 
<TABLE>
<CAPTION>
                                                                                               JUNE 30, 1998
                                                                                         -------------------------
                                                                                          ACTUAL    AS ADJUSTED(3)
                                                                                         ---------  --------------
<S>                                                                                      <C>        <C>
BALANCE SHEET DATA:
Cash and cash equivalents..............................................................  $  13,771    $   95,794
Payroll tax funds invested.............................................................    332,667       332,667
Working capital........................................................................      3,323        85,346
Total assets...........................................................................    376,009       458,032
Payroll tax funds collected but unremitted.............................................    332,667       332,667
Capital lease obligations, less current portion........................................      1,414         1,414
Total stockholders' equity.............................................................     26,746       108,769
</TABLE>
 
- ------------------------------
 
(1) As of June 30, 1998 (after giving effect to the Stock Split). Excludes (i)
    1,800,416 shares of Common Stock subject to outstanding options; (ii)
    229,500 shares of Common Stock issuable upon exercise of outstanding
    warrants; (iii) 1,277,510 shares of Common Stock reserved for future grant
    under the Company's 1996 Stock Option Plan; and (iv) 579,886 shares of
    Common Stock reserved for issuance under the Company's 1997 Employee Stock
    Purchase Plan. See "Management -- Stock Plans," "Description of Capital
    Stock -- Warrants" and Notes 6 and 7 of Notes to Financial Statements.
 
(2) See Note 1 of Notes to Financial Statements for an explanation of the
    determination of the shares used in computing historical and pro forma basic
    and diluted net loss per share.
 
(3) Adjusted to reflect the sale of the 2,475,000 shares of Common Stock offered
    hereby at an assumed public offering price of $35.17 per share, after
    deducting the estimated underwriting discount and estimated offering
    expenses payable by the Company, and application of the estimated net
    proceeds therefrom. See "Use of Proceeds" and "Capitalization."
 
    The Company was incorporated in California in October 1984 and
reincorporated in Delaware in September 1997. The Company's executive offices
are located at 4125 Hopyard Road, Pleasanton, California 94588, and its
telephone number is (925) 737-3500. The Company maintains a World Wide Web site
at www.probusiness.com. The information contained on the Company's Web site
shall not be deemed to be a part of this Prospectus.
 
                                       4
<PAGE>
                                  RISK FACTORS
 
    THIS PROSPECTUS CONTAINS FORWARD-LOOKING STATEMENTS THAT INVOLVE RISKS AND
UNCERTAINTIES. THE COMPANY'S ACTUAL RESULTS COULD DIFFER MATERIALLY FROM THOSE
ANTICIPATED IN THESE FORWARD-LOOKING STATEMENTS AS A RESULT OF CERTAIN FACTORS,
INCLUDING THOSE SET FORTH IN THE FOLLOWING RISK FACTORS AND ELSEWHERE IN THIS
PROSPECTUS. IN ADDITION TO THE OTHER INFORMATION IN THIS PROSPECTUS, THE
FOLLOWING RISK FACTORS SHOULD BE CONSIDERED CAREFULLY IN EVALUATING THE COMPANY
AND ITS BUSINESS BEFORE PURCHASING THE COMMON STOCK OFFERED BY THIS PROSPECTUS.
 
OPERATING LOSSES; NEED TO COMMIT TO EXPENSES IN ADVANCE OF REVENUE
 
    The Company has experienced significant operating losses since its inception
and expects to incur significant operating losses in the future due to continued
client acquisition costs, investments in research and development and costs
associated with expanding its sales efforts and operations to new geographic
regions. As of June 30, 1998, the Company had an accumulated deficit of
approximately $25.5 million. The establishment of new client relationships
involves lengthy and extensive sales and implementation processes. The sales
process generally takes three to twelve months or longer, and the implementation
process generally takes an additional three to nine months or longer. In
connection with the acquisition of each new client, the Company incurs
substantial client acquisition costs, which consist primarily of sales and
implementation expenses and, to a lesser extent, marketing expenses. The
Company's ability to achieve profitability will depend in part upon its ability
to attract and retain new clients, offer new services and features and achieve
market acceptance of new services. There can be no assurance that the Company
will achieve or sustain profitability in the future. The Company has made
acquisitions of businesses in the past and intends to pursue acquisitions in the
future. In connection with acquisitions, the Company has in the past incurred
and will likely incur in the future costs associated with adding personnel,
integrating technology, increasing overhead to support the acquired businesses,
acquiring in-process technology and amortization expenses related to intangible
assets. Any future acquisitions could have a material adverse effect on the
Company's business, financial condition and results of operations. See
"Management's Discussion and Analysis of Financial Condition and Results of
Operations."
 
SEASONALITY; FLUCTUATIONS IN QUARTERLY RESULTS
 
    The Company's business is characterized by significant seasonality. As a
result, the Company's revenue has been subject to significant seasonal
fluctuations, with the largest percentage of annual revenue being realized in
the third and fourth fiscal quarters, primarily due to new clients beginning
services in the beginning of the tax year (the Company's third fiscal quarter)
and higher interest income earned on payroll tax funds invested. Further, the
Company's operating expenses are typically higher as a percentage of revenue in
the first and second fiscal quarters as the Company increases personnel to
acquire new clients and to implement and provide services to such new clients, a
large percentage of which begin services in the third quarter.
 
    The Company's quarterly operating results have in the past and will in the
future vary significantly depending on a variety of factors, including the
number and size of new clients starting services, the decision of one or more
clients to delay or cancel implementation or ongoing services, interest rates,
seasonality, the ability of the Company to design, develop and introduce new
services and features for existing services on a timely basis, costs associated
with strategic acquisitions and alliances or investments in technology, the
success of any such strategic acquisition, alliance or investment, costs to
transition to new technologies, expenses incurred for geographic expansion,
risks associated with payroll tax and benefits administration services, price
competition, a reduction in the number of employees of its clients and general
economic factors. Revenue from new clients typically represents a significant
portion of quarterly revenue in the third and fourth fiscal quarters. A
substantial majority of the Company's operating expenses, particularly personnel
and related costs, depreciation and rent, is relatively fixed in advance of any
particular quarter. The Company's agreements with its clients generally do not
have significant penalties for cancellation. As a result, any decision by a
client to delay or cancel implementation of the
 
                                       5
<PAGE>
Company's services or the Company's underutilization of personnel may cause
significant variations in operating results in a particular quarter and could
result in losses for such quarter. As the Company secures larger clients, the
time required for implementing the Company's services increases, which could
contribute to larger fluctuations in revenue. Interest income earned from
investing payroll tax funds, which is a significant portion of the Company's
revenue, is vulnerable to fluctuations in interest rates. In addition, the
Company's business may be affected by shifts in the general condition of the
economy, client staff reductions, strikes, acquisitions of its clients by other
companies and other downturns. There can be no assurance that the Company's
future revenue and results of operations will not vary substantially. It is
possible that in some future quarter the Company's results of operations will be
below the expectations of public market analysts and investors. In either case,
the market price of the Company's Common Stock could be materially adversely
affected. See "Management's Discussion and Analysis of Financial Condition and
Results of Operations."
 
RISKS ASSOCIATED WITH STRATEGIC ACQUISITIONS AND INVESTMENTS
 
    While the Company has no current agreements or negotiations underway with
respect to any acquisition of, or investment in, businesses that provide
complementary services or technologies to those of the Company, the Company
intends to make additional acquisitions of, and investments in, such businesses.
There can be no assurance that any future acquisition will be completed or that,
if completed, will be effectively assimilated into the Company's business. In
addition, future acquisitions could result in the issuance of dilutive equity
securities, the incurrence of debt or contingent liabilities, and amortization
expenses related to goodwill and other intangible assets, any of which could
have a material adverse effect on the Company's business, financial condition
and results of operations. Furthermore, there can be no assurance that any
strategic investment will succeed. The initial cost of such an investment or the
failure of such an investment to succeed could have a material adverse effect on
the Company's business, financial condition and results of operations. See "--
Seasonality; Fluctuations in Quarterly Results," "Use of Proceeds,"
"Management's Discussion and Analysis of Financial Condition and Results of
Operations" and "Business -- Strategy."
 
RISKS ASSOCIATED WITH PAYROLL TAX FILING SERVICE AND BENEFITS ADMINISTRATION
  SERVICES
 
    The Company's payroll tax filing service is subject to various risks
resulting from errors and omissions in filing client tax returns and paying tax
liabilities owed to tax authorities on behalf of clients. The Company's clients
transfer to the Company contributed employer and employee tax funds. The Company
processes the data received from the client and remits the funds along with a
tax return to the appropriate tax authorities when due. Tracking, processing and
paying such tax liabilities is complex. Errors and omissions have occurred in
the past and may occur in the future in connection with such service. The
Company is subject to large cash penalties imposed by tax authorities for late
filings or underpayment of taxes. To date, such penalties have not been
significant. However, there can be no assurance that any liabilities associated
with such penalties will not have a material adverse effect on the Company's
business, financial condition and results of operations. There can be no
assurance that the Company's reserves or insurance for such penalties will be
adequate. In addition, failure by the Company to make timely or accurate tax
return filings or pay tax liabilities when due on behalf of clients may damage
the Company's reputation and could adversely affect its relationships with
existing clients and its ability to gain new clients.
 
    The Company's payroll tax filing service is also dependent upon government
regulations, which are subject to continual changes. Failure by the Company to
implement these changes into its services and technology in a timely manner
would have a material adverse effect on the Company's business, financial
condition and results of operations. In addition, since a significant portion of
the Company's revenue is derived from interest earned from investing on
collected but unremitted payroll tax funds, changes in policies relating to
withholding federal or state income taxes or reduction in the time allowed for
taxpayers
 
                                       6
<PAGE>
to remit payment for taxes owed to government authorities would have a material
adverse effect on the Company's business, financial condition and results of
operations.
 
    The Company's benefits administration services are subject to various risks
resulting from errors and omissions in processing and filing COBRA or other
benefit plan forms in accordance with governmental regulations and the
respective plans. The Company processes data received from employees and
employers and is subject to penalties for any late or misfiled plan forms. There
can be no assurance the Company's reserves or insurance for such penalties will
be adequate. In addition, failure to properly file plan forms would have a
material adverse effect on the Company's reputation, which could adversely
affect its relationships with existing clients and its ability to gain new
clients. The Company's benefits administration services are also dependent upon
government regulations which are subject to continuous changes that could reduce
or eliminate the need for benefits administration services.
 
    The Company has access to confidential information and to client funds. As a
result, the Company is subject to potential claims by its clients for the
actions of the Company's employees arising from damages to the client's business
or otherwise. There can be no assurance that the Company's fidelity bond and
errors and omissions insurance will be adequate to cover any such claims. Such
claims could have a material adverse effect on the Company's business, financial
condition and results of operations. See "Business -- Service Offerings."
 
INVESTMENT RISKS
 
    The Company invests funds, including payroll tax funds transferred to it by
clients, until the Company remits the funds to tax authorities when due. The
Company typically invests these funds in short-term financial instruments such
as overnight U.S. government direct and agency obligations repurchase
agreements, commercial paper rated A-1 and/or P-1 and money market funds with an
underlying credit quality of AA or better. These investments are exposed to
several risks, including credit risks from the possible inability of the
borrowers to meet the terms of their obligations under the financial
instruments. The Company would be liable for any losses on such investments.
 
    Interest income earned from investing these funds represents a significant
portion of the Company's revenues. As a result, the Company's business,
financial condition and results of operations are significantly impacted by
interest rate fluctuations. The Company enters into interest rate swap
agreements to minimize the impact of interest rate fluctuations. There can be no
assurance, however, that the Company's swap arrangements will protect the
Company from all interest rate risks. Under certain circumstances if interest
rates rise, the Company would have payment obligations under its interest rate
swap agreements which may not be offset by interest earned by the Company on
deposited funds. A payment obligation under the Company's swap arrangements
could have a material adverse effect on the Company's business, financial
condition and results of operations. In addition, there can be no assurance that
the Company would have sufficient funds to meet any such swap payment
obligations. A default by the Company under its swap agreements could result in
acceleration and set-off by the bank of all outstanding contracts under the swap
agreement, and could result in cross-defaults of other debt agreements of the
Company, any of which could have a material adverse effect on the Company's
business, financial condition and results of operations. See "Management's
Discussion and Analysis of Financial Condition and Results of Operations."
 
MANAGEMENT OF GROWTH
 
    The Company's business has grown significantly in size and complexity over
the past four years. The Company's number of employees has increased from 325 at
the end of fiscal 1997 to 500 at the end of fiscal 1998. This growth has placed,
and is expected to continue to place, significant demands on the Company's
management, systems, internal controls, and financial and physical resources. In
order to meet such demands, the Company intends to continue to hire new
employees, open new offices to attract clients in
 
                                       7
<PAGE>
new geographic regions, increase expenditures on research and development, and
invest in new equipment and make other capital expenditures. In addition, the
Company expects that it will need to develop further its financial and
managerial controls and reporting systems and procedures to accommodate any
future growth. Failure to expand any of the foregoing areas in an efficient
manner could have a material adverse effect on the Company's business, financial
condition and results of operations. The Company intends to open a satellite
sales and implementation center in New Jersey by the end of calendar 1998 and
may open additional sales offices in the future. In addition, the Company
intends to move its benefits administration center from its current location in
Bellevue, Washington to another location there, and the Company has leased
additional office space to be built adjacent to its Pleasanton headquarters.
There can be no assurance that the Company will be able to establish such
facilities on a timely basis. The Company's growth may depend to some extent on
its ability to successfully complete strategic acquisitions or investments to
expand or complement its existing business. There can be no assurance that
suitable acquisitions or investments can be identified, consummated or
successfully integrated into the Company's operations. Any inability to manage
growth effectively could have a material adverse effect on the Company's
business, financial condition and results of operations. See "Management's
Discussion and Analysis of Financial Condition and Results of Operations."
 
SUBSTANTIAL COMPETITION
 
    The market for the Company's services is intensely competitive, subject to
rapid change and significantly affected by new service introductions and other
market activities of industry participants. The Company primarily competes with
several public and private payroll service providers, such as Automatic Data
Processing, Inc., Ceridian Corporation and Paychex, Inc., as well as smaller,
regional competitors. Many of these companies have longer operating histories,
greater financial, technical, marketing and other resources, greater name
recognition and a larger number of clients than the Company. In addition,
certain of these companies offer more services or features than the Company and
have processing facilities located throughout the United States. The Company
also competes with in-house employee services departments and, to a lesser
extent, banks and local payroll companies. With respect to benefits
administration services, the Company competes with insurance companies, benefits
consultants and other local benefits outsourcing companies. The Company may also
compete with marketers of related products and services that may offer payroll
or benefits administration services in the future. The Company has experienced,
and expects to continue to experience, competition from new entrants into its
markets. Increased competition, the failure of the Company to compete
successfully, pricing pressures, loss of market share and loss of clients could
have a material adverse effect on the Company's business, financial condition
and results of operations. See "Business -- Competition."
 
RELIANCE ON RAPIDLY CHANGING TECHNOLOGY; RISKS OF SOFTWARE DEFECTS
 
    The technologies in which the Company has invested to date are rapidly
evolving and have short life cycles, which requires the Company to anticipate
and rapidly adapt to technological changes. In addition, the Company's industry
is characterized by increasingly sophisticated and varied needs of clients,
frequent new service and feature introductions and emerging industry standards.
The introduction of services embodying new technologies and the emergence of new
industry standards and practices can render existing services obsolete and
unmarketable. The Company's future success will depend, in part, on its ability
to develop or acquire advanced technologies, enhance its existing services with
new features, add new services that address the changing needs of its clients,
and respond to technological advances and emerging industry standards and
practices on a timely and cost-effective basis. Several of the Company's
competitors invest substantially greater amounts in research and development
than the Company, which may allow them to introduce new services or features
before the Company. Even if the Company is able to develop or acquire new
technologies in a timely manner, it may incur substantial costs in developing or
acquiring such technologies and in deploying new services and features to its
clients, including costs associated with acquiring in-process technology,
amortization expenses related to intangible assets and
 
                                       8
<PAGE>
costs of additional personnel. If the Company is unable to develop or acquire
and successfully introduce new services and new features of existing services in
a timely or cost-effective manner, the Company's business, financial condition
and results of operations could be materially adversely affected. See "Business
- -- Service Offerings" and "-- Research and Development."
 
    Application software used by the Company may contain defects or failures
when introduced or when new versions or enhancements are released. The Company
has in the past discovered software defects in certain of its applications, in
some cases only after its systems have been used by clients. There can be no
assurance that future defects will not be discovered in existing or new
applications or releases. Any such occurrence could have a material adverse
effect upon the Company's business, financial condition and results of
operations. See "Business -- Technology" and "-- Research and Development."
 
DEPENDENCE ON THIRD-PARTY PROVIDERS
 
    The Company depends on third-party courier services to deliver paychecks to
clients. The Company does not have any formal written agreements with any of the
courier services that it uses. Such courier services have been in the past and
may be in the future unable to timely pick up or deliver the paychecks from the
Company to its clients for a variety of reasons, including employee strikes,
storms or other adverse weather conditions, earthquakes or other natural
disasters, logistical or mechanical failures or accidents. Failure by the
Company to deliver client paychecks on a timely basis could damage the Company's
reputation and have a material adverse effect on the Company's business,
financial condition and results of operations.
 
DISASTER RECOVERY; RISK OF LOSS OF CLIENT DATA
 
    The Company currently conducts substantially all of its payroll and payroll
tax processing at the Company's headquarters in Pleasanton, California and
divides the payroll printing and finishing between its Pleasanton and Irvine,
California facilities. The Irvine facility serves both as an alternative
processing center and a back-up payroll center. The Company's benefits
administration services are conducted solely in Bellevue, Washington, and no
benefits administration back-up facility exists. The Company establishes for
each payroll client a complete set of payroll data at the Pleasanton processing
center, as well as at the client's site. In the event of a disaster in
Pleasanton, clients would have the ability to process payroll checks based on
the data they have on site if necessary. There can be no assurance that the
Company's disaster recovery procedures are sufficient or that the payroll data
recovered at the client site would be sufficient to allow the client to
calculate and produce payroll in a timely fashion.
 
    The Company's operations are dependent on its ability to protect its
computer systems against damage from a major catastrophe (such as an earthquake
or other natural disaster), fire, power loss, security breach,
telecommunications failure or similar event. No assurance can be given that the
precautions that the Company has taken to protect itself from or minimize the
impact of such events will be adequate. Any damage to the Company's data
centers, failure of telecommunications links or breach of the security of the
Company's computer systems could result in an interruption of the Company's
operations or other loss which may not be covered by the Company's insurance.
Any such event could have a material adverse effect on the Company's business,
financial condition and results of operations.
 
NEED TO ATTRACT AND RETAIN EXPERIENCED PERSONNEL
 
    The Company's success depends to a significant degree on its ability to
attract and retain experienced employees. There is substantial competition for
experienced personnel, which the Company expects to continue. Many of the
companies with which the Company competes for experienced personnel have greater
financial and other resources than the Company. The Company has in the past and
may in the future experience difficulty in recruiting sufficient numbers of
qualified personnel. In particular, the Company's ability to find and train
implementation employees is critical to the Company's ability to
 
                                       9
<PAGE>
achieve its growth objectives. The inability to attract and retain experienced
personnel as required could have a material adverse effect on the Company's
business, financial condition and results of operations. See "Business --
Competition," "-- Employees" and "Management."
 
RISKS ASSOCIATED WITH GEOGRAPHIC EXPANSION
 
    A substantial majority of the Company's revenue historically has been
derived from clients located in the western United States. The Company's ability
to achieve significant future revenue growth will in large part depend on its
ability to gain new clients throughout the United States. By the end of calendar
1998, the Company intends to open a satellite sales and implementation center in
New Jersey to service the eastern United States. The Company may open additional
sales offices in the future. Due to the time required to sell and implement the
Company's services and the fixed costs associated with opening a new center, any
revenue associated with a new center will be significantly lower than the costs
associated with it, potentially for a significant period of time. Growth and
geographic expansion have resulted in new and increased responsibilities for
management personnel and has placed and continues to place a significant strain
on the Company's management and operating and financial systems. The Company
will be required to continue to implement and improve its systems on a timely
basis and in such a manner as is necessary to accommodate the increased number
of transactions and clients and the increased size of the Company's operations.
Any failure to implement and improve the Company's systems or to hire and retain
the appropriate personnel to manage its operations would have a material adverse
effect on the Company's business, financial condition and results of operations.
In addition, an increase in the Company's operating expenses from its planned
expansion will have a material adverse effect on the Company's business,
financial condition and results of operations if revenue does not increase to
support such expansion. See "Management's Discussion and Analysis of Financial
Condition and Results of Operations" and "Business -- Sales and Marketing."
 
RISKS ASSOCIATED WITH THE DEVELOPMENT AND INTRODUCTION OF NEW OR ENHANCED
  SERVICES
 
    The Company's future business, financial condition and results of operations
will continue to depend upon the Company's ability to add new services or
enhancements to existing services that address the needs of the market. Failure
by the Company to successfully design, develop, integrate and introduce new
services or enhancements on a timely basis could prevent the Company from
maintaining existing client relationships, gaining new clients or expanding its
markets and could have a material adverse effect on the Company's business,
financial condition and results of operations. See "Business -- Research and
Development."
 
DEPENDENCE ON KEY PERSONNEL
 
    The Company's success will depend on the performance of the Company's senior
management and other key employees. The loss of the services of any senior
management or other key employee could have a material adverse effect on the
Company's business, financial condition and results of operations. The Company
generally does not enter into employment or noncompetition agreements with its
employees. If one or more of the Company's key employees resigns from the
Company to join a competitor or to form a competitor, the loss of such personnel
and any resulting loss of existing or potential clients to any such competitor
could have a material adverse effect on the Company's business, financial
condition and results of operations. In the event of the loss of any key
personnel, there can be no assurance that the Company would be able to prevent
the unauthorized disclosure or use of its technical knowledge, practices,
procedures or client lists by a former employee or that such disclosure or use
would not have a material adverse effect on the Company's business, financial
condition and results of operations. See "Business -- Employees" and
"Management."
 
                                       10
<PAGE>
IMPACT OF YEAR 2000 COMPLIANCE
 
    Many currently installed computer systems and software products are coded to
accept only two digit entries in the date code field. Beginning in 2000, these
date code fields will need to accept four digit entries in order to distinguish
21st century dates from 20th century dates. As a result, computer systems and/or
software used by many companies will need to be upgraded to comply with "Year
2000" requirements by the end of 1999. Significant uncertainty exists in the
software industry concerning the potential effects associated with such
compliance issues.
 
    The Company has conducted a preliminary review of its internal computer
systems to identify the systems that could be affected by the Year 2000 issue
and to develop a plan to make its systems Year 2000 compliant. Based on this
preliminary review, the Company has discovered certain failures to comply with
Year 2000 requirements. The Company is taking action to correct the
non-complying features of its systems, and the Company believes that its
internal software systems will be Year 2000 compliant by 2000. There can be no
assurance, however, that the Company's systems will be fully Year 2000 compliant
in a timely manner, and a failure by the Company to make its internal systems
Year 2000 compliant could have a material adverse effect on the Company's
business, financial condition and results of operations. The Company has not
determined an estimate of the costs required to correct the non-complying
features, and the Company does not currently have a contingency plan in the
event that it is unable to make its systems Year 2000 compliant. Additionally,
the costs of making such systems Year 2000 compliant could have a material
adverse effect on the Company's business, financial condition and results of
operations.
 
    The Company believes that its current products are, and future products will
be, fully Year 2000 compliant. The Company's past software products, many of
which are currently used by clients, are not Year 2000 compliant. The Company
has begun the process of transitioning existing clients to its Year 2000
compliant products; however, there can be no assurance that the Company will be
successful in providing all of its clients with Year 2000 compliant products by
2000. Any failure by the Company to transition its clients to Year 2000
compliant products could have a material adverse effect on the Company's
business, financial condition and results of operations. In addition, there can
be no assurance that Year 2000 errors or defects will not be discovered in the
Company's current and future products.
 
    The Company is not assessing the Year 2000 compliance of its clients'
systems or the possible effects on its operations of the Year 2000 compliance of
its clients' systems. Due to the substantial integration between the Company's
computer systems and its clients' systems, the failure by the Company's clients
to have Year 2000 compliant systems could have a material adverse effect on the
Company's business, financial condition and results of operations. The Company
is assessing the possible effects on its operations of the Year 2000 readiness
of key suppliers and subcontractors. The Company's reliance on suppliers and
subcontractors, and, therefore, on the proper functioning of their information
systems and software, means that failure by such suppliers and subcontractors to
address Year 2000 issues could have a material adverse effect on the Company's
business, financial condition and results of operations. See "Management's
Discussion and Analysis of Financial Condition and Results of Operations -- Year
2000 Compliance."
 
LIMITATIONS ON PROTECTION OF INTELLECTUAL PROPERTY AND PROPRIETARY RIGHTS
 
    The Company's success is dependent in part upon its proprietary software
technology. The Company has no patents, patent applications or registered
copyrights. The Company relies on a combination of contract, copyright and trade
secret laws to establish and protect its proprietary technology. The Company
distributes its services under software license agreements that grant clients
licenses to use the Company's services and contain various provisions protecting
the Company's ownership and the confidentiality of the underlying technology.
The Company generally enters into confidentiality and/or license agreements with
its employees and existing and potential clients, and limits access to and
distribution of its software, documentation and other proprietary information.
There can be no assurance that the steps taken by the
 
                                       11
<PAGE>
Company in this regard will be adequate to deter misappropriation or independent
third-party development of the Company's technology. There can be no assurance
that the Company's services and technology do not infringe any existing patents,
copyrights or other proprietary rights of others, or that third parties will not
assert infringement claims in the future. If any such claims are asserted and
upheld, the costs of defense could be substantial and any resulting liability to
the Company could have a material adverse effect on the Company's business,
financial condition and results of operations. See "Business -- Proprietary
Rights."
 
UNALLOCATED NET PROCEEDS
 
    The Company has not designated any specific use for the net proceeds of the
Offering. The Company currently expects to use the net proceeds for general
corporate purposes, including capital expenditures and working capital. The
Company also may use a portion of the net proceeds for the acquisition of
companies, technology or services that complement the business of the Company or
for strategic alliances with, or investments in, companies that provide
complementary products and services. Accordingly, management will have
significant discretion in applying the net proceeds of the Offering. See "Use of
Proceeds."
 
CONCENTRATION OF STOCK OWNERSHIP
 
    Upon completion of this Offering, the Company's directors and executive
officers and their respective affiliates will beneficially own 36.7% (36.0% if
the Underwriters' over-allotment option is exercised in full) of the outstanding
Common Stock. As a result, these stockholders, if they act together, will be
able to exercise significant influence over all matters requiring stockholder
approval, including the election of directors and approval of significant
corporate transactions, and will have power to influence any stockholder action
or approval requiring a majority vote. Such concentration of ownership may also
have the effect of delaying, deferring or preventing a change of control of the
Company. See "Principal Stockholders" and "Description of Capital Stock."
 
POSSIBLE VOLATILITY OF STOCK PRICE
 
    The market price of the Company's Common Stock is likely to be highly
volatile following this Offering and could be subject to wide fluctuations in
response to quarterly variations in operating results, announcements of
technological innovations or new services by the Company or its competitors,
market conditions in the information services industry, changes in financial
estimates by securities analysts or other events or factors, many of which are
beyond the Company's control. In addition, the stock market has experienced
significant price and volume fluctuations that have particularly affected the
market prices of equity securities of many technology and services companies and
that often have been unrelated to the operating performance of such companies.
These broad market fluctuations may adversely affect the market price of the
Company's Common Stock.
 
SUBSTANTIAL DILUTION
 
    The assumed public offering price is substantially higher than the net
tangible book value per share of the outstanding Common Stock. As a result,
purchasers of the Common Stock offered hereby will incur immediate, substantial
dilution in the amount of $30.11 per share. To the extent that outstanding
options or warrants to purchase the Company's Common Stock are exercised, there
will be further dilution. The Company has in the past granted a substantial
number of options to purchase Common Stock to employees as part of compensation
packages at exercise prices per share lower than the price per share of Common
Stock offered hereby, and the Company expects that it will continue to grant a
substantial number of options in the future at the fair market value of the
Common Stock at such time, which possibly could be a price per share lower than
the price per share of Common Stock offered hereby. In addition, the Company's
employee stock purchase plan provides employees an opportunity to purchase
shares below
 
                                       12
<PAGE>
prevailing market value. The Company also may issue shares of its Common Stock
in connection with strategic acquisitions or alliances. Any of the foregoing
could also result in dilution to stockholders. See "Dilution."
 
SHARES ELIGIBLE FOR FUTURE SALE
 
    Sales of substantial numbers of shares of Common Stock in the public market
following this Offering could adversely affect the market price of the Common
Stock. Upon completion of this Offering, the Company will have outstanding an
aggregate of 19,589,855 shares of Common Stock, based upon the number of shares
outstanding as of June 30, 1998. Of these shares, all of the shares sold in this
Offering and the 4,312,500 shares sold in the Company's initial public offering
will be freely tradeable without restriction or further registration under the
Securities Act. There are currently outstanding 2,539,100 shares of Common Stock
issued pursuant to exercise of options granted under equity incentive plans of
the Company, all of which shares are freely tradeable pursuant to Rule 701 of
the Securities Act or have been registered for resale under the Securities Act.
The remaining 10,263,255 shares of Common Stock were issued and sold by the
Company in private transactions exempt from registration requirements of the
Securities Act and will be available for immediate sale in the public market in
accordance with Rule 144, in some cases subject to the volume and other resale
limitations of Rule 144, other than the one-year holding period. Approximately
7,127,890 of such shares are subject to lock-up agreements under which the
holders of such shares have agreed with William Blair & Company, L.L.C. not to
sell or otherwise dispose of any of such shares for a period of 90 days
following the date of this Prospectus, subject to certain limited exceptions.
See "Shares Eligible for Future Sale."
 
    As of June 30, 1998, options to purchase 1,800,416 shares of Common Stock
were outstanding, of which options to purchase 414,884 shares were then
exercisable. As of June 30, 1998, 1,277,510 shares of Common Stock were
available for grant pursuant to the Company's 1996 Stock Option Plan and 579,886
shares of Common Stock were available for issuance pursuant to the Company's
1997 Employee Stock Purchase Plan. In addition, as of June 30, 1998, warrants to
purchase 229,500 shares of Common Stock were outstanding, all of the underlying
shares of which will be eligible for sale in the public market upon exercise of
the warrants.
 
    Pursuant to agreements between the Company and certain stockholders and
warrantholders (or their permitted transferees), approximately 9,571,976 shares
of Common Stock and 124,500 shares issuable upon exercise of warrants are
entitled to certain registration rights under the Securities Act. See
"Description of Capital Stock" and "Shares Eligible for Future Sale."
 
ANTI-TAKEOVER EFFECTS OF CERTIFICATE OF INCORPORATION, BYLAWS AND DELAWARE LAW
 
    The Company's Board of Directors has the authority to issue up to 5,000,000
shares of Preferred Stock and to determine the price, rights, preferences,
privileges and restrictions, including voting rights, of those shares without
any further vote or action by the Company's stockholders. The rights of the
holders of Common Stock will be subject to, and may be adversely affected by,
the rights of the holders of any Preferred Stock that may be issued in the
future. The issuance of Preferred Stock, while providing flexibility in
connection with possible acquisitions and other corporate purposes, could have
the effect of making it more difficult for a third party to acquire a majority
of the outstanding voting stock of the Company. In addition, such Preferred
Stock may have other rights, including economic rights, senior to the Common
Stock, and, as a result, the issuance thereof could have a material adverse
effect on the market value of the Common Stock. The Company has no present plans
to issue shares of Preferred Stock.
 
    In addition, the Company is subject to the anti-takeover provisions of
Section 203 of the Delaware General Corporation Law, which prohibit the Company
from engaging in a "business combination" with an "interested stockholder" for a
period of three years after the date of the transaction in which the person
became an interested stockholder, unless the business combination is approved in
a prescribed manner.
 
                                       13
<PAGE>
The application of Section 203 also could have the effect of delaying or
preventing a change of control of the Company. Further, certain other provisions
of the Company's Amended and Restated Certificate of Incorporation and Bylaws
and of Delaware law could delay or make more difficult a merger, tender offer or
proxy contest involving the Company. These provisions include a classified
board, advance notice procedures for stockholders to nominate candidates for
election as directors of the Company, authorization of the Board of Directors to
alter the number of directors without stockholder approval, limitations on
persons who can call stockholder meetings, lack of cumulative voting and
prohibition of stockholder actions by written consent. See "Description of
Capital Stock -- Preferred Stock" and "-- Delaware Law and Certain Charter and
Bylaw Provisions."
 
                   SAFE HARBOR FOR FORWARD-LOOKING STATEMENTS
 
    Forward-looking statements contained in this Prospectus are subject to the
safe harbor created by the Private Securities Litigation Reform Act of 1995 and
are highly dependent upon a variety of important factors that could cause actual
results to differ materially from those reflected in such forward looking
statements. When used in this document and documents referenced herein, the
words "intend," "anticipate," "believe," "estimate," and "expect" and similar
expressions as they relate to the Company are included to identify such forward
looking statements. These forward-looking statements include statements
regarding the demand for outsourcing employee administrative services; the
Company's expansion of its client base; the Company's intention to increase its
direct sales force; the development of a comprehensive and fully integrated
suite of employee administrative services; the Company's ability to offer
additional services; the initiation or completion of any strategic acquisition,
investment or alliance; the Company's ability to extend its technology
leadership; the Company's ability to attract and retain new clients; market
acceptance of any new services offered by the Company; the Company's ability to
minimize the impact of interest rate fluctuations; the Company's ability to
develop its financial and managerial controls and systems; the opening of
additional facilities; the sufficiency of the Company's back-up facilities and
disaster recovery procedures; the Company's ability to develop or acquire new
technologies; the Company's ability to attract and retain experienced employees;
the ability of the Company to make its internal system Year 2000 compliant and
to transition its clients to a Year 2000 compliant system; the Company's ability
to maintain a high payroll client retention rate and the Company's ability to
increase its national presence. These forward-looking statements are based
largely on the Company's current expectations and are subject to a number of
risks and uncertainties, including without limitation, those identified under
"Risk Factors" and elsewhere in this Prospectus and other risks and
uncertainties indicated from time to time in the Company's filings with the
Securities and Exchange Commission. Actual results could differ materially from
these forward-looking statements. In addition, important factors to consider in
evaluating such forward-looking statements include changes in external market
factors, changes in the Company's business or growth strategy or an inability to
execute its strategy due to changes in its industry or the economy generally,
the emergence of new or growing competitors and various other competitive
factors. In light of these risks and uncertainties, there can be no assurance
that the forward-looking statements contained in this Prospectus will in fact
occur.
 
                                       14
<PAGE>
                                USE OF PROCEEDS
 
    The net proceeds from the sale of the 2,475,000 shares of Common Stock
offered hereby are estimated to be approximately $82.0 million ($94.4 million if
the Underwriters' over-allotment option is exercised in full) at an assumed
public offering price of $35.17 per share and after deducting the estimated
underwriter discount and estimated offering expenses payable by the Company. The
Company intends to use the net proceeds of this Offering for general corporate
purposes, including capital expenditures and working capital. The Company also
may use a portion of the net proceeds for the acquisition of, or investments in,
companies, technology or services that complement the business of the Company or
for strategic alliances with, or investments in, companies that provide
complementary products and services. No such transactions, alliances or
investments are currently planned. The amounts actually expended may vary
depending upon numerous factors. Pending the foregoing uses, the Company intends
to invest the net proceeds from this Offering in investment-grade, short-term,
interest-bearing securities, money market funds or similar short-term
investments.
 
                                DIVIDEND POLICY
 
    The Company has never declared or paid any cash dividends on its capital
stock. The Company currently intends to retain its earnings, if any, for use in
its business and does not anticipate paying any cash dividends in the
foreseeable future. In addition, the Company's working capital line of credit
agreement prohibits the payment of cash dividends without the lender's prior
approval.
 
                          PRICE RANGE OF COMMON STOCK
 
    The Company's Common Stock is quoted on the Nasdaq National Market under the
symbol "PRBZ." The following table sets forth, for the fiscal periods indicated,
the high and low sales prices of the Common Stock as reported by the Nasdaq
National Market since the Company's initial public offering of Common Stock at
$7.33 per share on September 19, 1997 (after giving effect to the Stock Split).
Prior to September 19, 1997, there was no public trading market for the Common
Stock.
 
<TABLE>
<CAPTION>
                                                                               HIGH        LOW
                                                                             ---------  ---------
<S>                                                                          <C>        <C>
FISCAL 1998:
  First Quarter (from September 19, 1997)..................................  $   12.92  $    7.67
  Second Quarter...........................................................      15.33      12.08
  Third Quarter............................................................      20.00      14.00
  Fourth Quarter...........................................................      32.58      17.33
FISCAL 1999:
  First Quarter (through August 4, 1998)...................................  $   43.13  $   29.75
</TABLE>
 
    On July 31, 1998, there were 372 holders of record of the Company's Common
Stock. The Company believes that the number of beneficial owners of the Common
Stock is substantially greater than the number of record owners because a large
portion of the Common Stock is held of record in broker "street names." The last
reported sale price per share of the Common Stock on August 4, 1998 on the
Nasdaq National Market was $52.75 (equivalent to $35.167 after giving effect to
the Stock Split).
 
                                       15
<PAGE>
                                 CAPITALIZATION
 
    The following table sets forth the short-term indebtedness and total
capitalization of the Company as of June 30, 1998 on an actual basis and on an
as adjusted basis to give effect to the sale and issuance of the shares of
Common Stock offered hereby at an assumed public offering price of $35.17 per
share (after deducting the estimated underwriting discount and estimated
offering expenses payable by the Company) and receipt and application of the
estimated net proceeds therefrom. See "Use of Proceeds." This table should be
reviewed in conjunction with the Financial Statements and Notes thereto
appearing elsewhere in this Prospectus.
 
<TABLE>
<CAPTION>
                                                                                                JUNE 30, 1998
                                                                                           -----------------------
                                                                                             ACTUAL    AS ADJUSTED
                                                                                           ----------  -----------
                                                                                               (IN THOUSANDS)
<S>                                                                                        <C>         <C>
Current portion of capital lease obligations.............................................  $      890   $     890
                                                                                           ----------  -----------
                                                                                           ----------  -----------
Capital lease obligations, less current portion (1)......................................       1,414       1,414
Stockholders' equity:
  Preferred Stock, $.001 par value; 5,000,000 shares authorized, no shares issued and
   outstanding...........................................................................      --          --
  Common Stock, $.001 par value; 60,000,000 shares authorized, 17,114,855 shares issued
   and outstanding, actual; 19,589,855 shares issued and outstanding, as adjusted (2)....          17          20
Additional paid-in capital...............................................................      53,286     135,306
Accumulated deficit......................................................................     (25,469)    (25,469)
Notes receivable from stockholders.......................................................      (1,088)     (1,088)
                                                                                           ----------  -----------
    Total stockholders' equity...........................................................      26,746     108,769
                                                                                           ----------  -----------
      Total capitalization...............................................................  $   28,160   $ 110,183
                                                                                           ----------  -----------
                                                                                           ----------  -----------
</TABLE>
 
- ------------------------
 
(1) See Note 4 of Notes to Financial Statements.
 
(2) As of June 30, 1998 (after giving effect to the Stock Split). Excludes (i)
    1,800,416 shares of Common Stock subject to outstanding options; (ii)
    229,500 shares of Common Stock issuable upon exercise of outstanding
    warrants; (iii) 1,277,510 shares of Common Stock reserved for future grant
    under the Company's 1996 Stock Option Plan; and (iv) 579,886 shares of
    Common Stock reserved for issuance under the Company's 1997 Employee Stock
    Purchase Plan. See "Management -- Stock Plans," "Description of Capital
    Stock -- Warrants" and Notes 6 and 7 of Notes to Financial Statements.
 
                                       16
<PAGE>
                                    DILUTION
 
    The net tangible book value of the Company as of June 30, 1998 was
approximately $17.0 million or $0.99 per share of Common Stock. Net tangible
book value per share represents the amount of the Company's total net tangible
assets less total liabilities, divided by the number of shares of Common Stock
issued and outstanding at that date. Dilution per share to new stockholders
represents the difference between the amount paid by purchasers of shares of
Common Stock in the Offering made hereby and the as adjusted net tangible book
value per share of Common Stock immediately after the completion of this
Offering. After giving effect to the sale of the shares of Common Stock offered
hereby at an assumed public offering price of $35.17 per share and after
deduction of the estimated underwriting discount and estimated offering expenses
payable by the Company, the net tangible book value of the Company as of June
30, 1998, would have been approximately $99.0 million or $5.06 per share. This
represents an immediate increase in net tangible book value of $4.07 per share
to existing stockholders and an immediate dilution of $30.11 per share to new
stockholders purchasing Common Stock in this Offering. The following table
illustrates this per share dilution:
 
<TABLE>
<S>                                                                 <C>        <C>
Assumed public offering price per share...........................             $   35.17
                                                                               ---------
  Net tangible book value per share at June 30, 1998..............  $    0.99
                                                                    ---------
  Increase in net tangible book value per share attributable to
    new stockholders..............................................       4.07
                                                                    ---------
As adjusted net tangible book value per share after the
 Offering.........................................................                  5.06
                                                                               ---------
Dilution per share to new stockholders............................             $   30.11
                                                                               ---------
                                                                               ---------
</TABLE>
 
                                       17
<PAGE>
                            SELECTED FINANCIAL DATA
 
    The following selected statements of operations data for the years ended
June 30, 1996, 1997 and 1998 and the balance sheet data at June 30, 1997 and
1998 are derived from the financial statements of the Company, which have been
audited by Ernst & Young LLP, independent auditors, and are included elsewhere
in this Prospectus. The statements of operations data for the years ended June
30, 1994 and 1995 and the balance sheet data at June 30, 1994, 1995 and 1996 are
derived from financial statements of the Company that have been audited by Ernst
& Young LLP that are not included in this Prospectus. The following selected
financial data should be read in conjunction with "Management's Discussion and
Analysis of Financial Condition and Results of Operations" and Financial
Statements and Notes thereto included elsewhere in this Prospectus.
 
<TABLE>
<CAPTION>
                                                                             YEAR ENDED JUNE 30,
                                                           -------------------------------------------------------
                                                              1994        1995       1996       1997       1998
                                                           ----------  ----------  ---------  ---------  ---------
                                                                    (IN THOUSANDS, EXCEPT PER SHARE DATA)
<S>                                                        <C>         <C>         <C>        <C>        <C>
STATEMENTS OF OPERATIONS DATA:
Revenue..................................................  $    4,069  $    7,095  $  13,863  $  27,374  $  46,317
Operating expenses:
  Cost of providing services.............................       1,629       2,703      6,435     13,659     23,859
  General and administrative expenses....................       1,202       1,304      2,054      4,282      6,727
  Research and development expenses......................       1,202       1,038      1,257      2,841      4,585
  Client acquisition costs...............................       1,467       2,943      5,388     11,706     17,858
  Acquisition of in-process technology...................      --          --            711     --         --
                                                           ----------  ----------  ---------  ---------  ---------
Total operating expenses.................................       5,500       7,988     15,845     32,488     53,029
                                                           ----------  ----------  ---------  ---------  ---------
Loss from operations.....................................      (1,431)       (893)    (1,982)    (5,114)    (6,712)
Interest expense.........................................         (46)        (86)      (473)    (1,190)      (557)
Other income.............................................      --          --             69         59        752
                                                           ----------  ----------  ---------  ---------  ---------
Net loss.................................................  $   (1,477) $     (979) $  (2,386) $  (6,245) $  (6,517)
                                                           ----------  ----------  ---------  ---------  ---------
                                                           ----------  ----------  ---------  ---------  ---------
Historical basic and diluted net loss per share(1).......  $  (738.50) $  (139.86) $   (4.91)
                                                           ----------  ----------  ---------
                                                           ----------  ----------  ---------
Shares used in computing historical basic and diluted net
 loss per share(1).......................................           2           7        486
Pro forma basic and diluted net loss per share(1)........                                     $   (0.59) $   (0.41)
                                                                                              ---------  ---------
                                                                                              ---------  ---------
Shares used in computing pro forma basic and diluted net
 loss per share(1).......................................                                        10,533     15,722
</TABLE>
 
<TABLE>
<CAPTION>
                                                                                 JUNE 30,
                                                       ------------------------------------------------------------
                                                          1994         1995         1996        1997        1998
                                                       -----------  -----------  ----------  ----------  ----------
                                                                              (IN THOUSANDS)
<S>                                                    <C>          <C>          <C>         <C>         <C>
BALANCE SHEET DATA:
Cash and cash equivalents............................   $     114    $     852   $    4,041  $    5,047  $   13,771
Payroll tax funds invested...........................      --           --          106,339     177,626     332,667
Working capital (deficiency).........................        (119)          69        3,022          41       3,323
Total assets.........................................       2,019        4,134      117,228     200,435     376,009
Payroll tax funds collected but unremitted...........      --           --          106,339     177,626     332,667
Long-term debt and note payable to stockholder, less
 current portion.....................................         394        1,016        8,072       8,917      --
Capital lease obligations, less current portion......         174          168          253       1,898       1,414
Total stockholders' equity (deficit).................         705        1,366         (136)      3,869      26,746
</TABLE>
 
- ------------------------
 
(1) See Note 1 of Notes to Financial Statements for an explanation of the
    determination of the shares used in computing historical and pro forma basic
    and diluted net loss per share.
 
                                       18
<PAGE>
                      MANAGEMENT'S DISCUSSION AND ANALYSIS
                OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
 
    THE FOLLOWING MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION
AND RESULTS OF OPERATIONS CONTAINS FORWARD-LOOKING STATEMENTS THAT INVOLVE RISKS
AND UNCERTAINTIES. THE COMPANY'S ACTUAL RESULTS COULD DIFFER MATERIALLY FROM
THOSE ANTICIPATED IN THESE FORWARD-LOOKING STATEMENTS AS A RESULT OF CERTAIN
FACTORS, INCLUDING THOSE SET FORTH UNDER "RISK FACTORS" AND ELSEWHERE IN THIS
PROSPECTUS. THE FOLLOWING DISCUSSION ALSO SHOULD BE READ IN CONJUNCTION WITH THE
FINANCIAL STATEMENTS AND NOTES THERETO INCLUDED ELSEWHERE IN THIS PROSPECTUS.
 
OVERVIEW
 
    ProBusiness Services, Inc. is a leading provider of employee administrative
services for large employers. The Company's primary service offerings are
payroll processing, payroll tax filing, benefits administration, including the
enrollment and processing of flexible benefit plans and COBRA programs, and
human resources software. The Company's proprietary PC-based payroll system
offers the cost-effective benefits of outsourcing and high levels of client
service, while providing the flexibility, control, customization and integration
of an in-house system.
 
    Since 1994, the Company has experienced significant growth of its revenue,
client base and average client size. Revenue increased from $4.1 million in
fiscal 1994 to $46.3 million in fiscal 1998. From June 30, 1994 to June 30,
1998, the client base for payroll processing services increased from 200 to
approximately 510 clients, while the average size of the Company's payroll
clients increased from approximately 400 employees to approximately 1,100
employees. The number of checks that the Company processed for its payroll
clients increased from 2.9 million to 4.3 million for the quarters ended June
30, 1997 and 1998, respectively. As of June 30, 1998, the Company provided
services to approximately 1,400 clients. The Company's revenue growth is
primarily due to continued growth in its client base, the introduction of its
payroll tax service in fiscal 1996, an increase in the average size of its
clients, the introduction of new features and other services, and a high
retention rate of existing payroll clients (approximately 92% for fiscal 1998).
The Company does not anticipate it will sustain this rate of growth in the
future.
 
    The establishment of new client relationships involves lengthy and extensive
sales and implementation processes. The sales process generally takes three to
twelve months or longer, and the implementation process generally takes an
additional three to nine months or longer. In connection with the acquisition of
each new client, the Company incurs substantial client acquisition costs, which
consist primarily of sales and implementation expenses and, to a lesser extent,
marketing expenses. In addition, the Company's revenue is subject to significant
seasonal fluctuations, with the largest percentage of annual revenue being
realized in the third and fourth fiscal quarters, primarily due to new clients
beginning services in the beginning of the tax year (the Company's third fiscal
quarter) and higher interest income earned on tax funds. Further, the Company's
operating expenses are typically higher as a percentage of revenue in the first
and second fiscal quarters as the Company increases personnel to acquire new
clients and to implement and provide services to such new clients, a large
percentage of which begin services in the third quarter. The Company expects
this pattern to continue. The Company has experienced significant operating
losses since its inception and expects to incur significant operating losses in
the future due to continued client acquisition costs, investments in research
and development and costs associated with expanding its sales efforts and
operations to new geographic regions. As of June 30, 1998, the Company had an
accumulated deficit of approximately $25.5 million. There can be no assurance
that the Company will achieve or sustain profitability in the future.
 
    The Company derives its revenue from fees charged to clients for services
and income earned from investing payroll tax funds. The Company generally
recognizes revenue from services when such services are performed and recognizes
income from investments when earned. The Company typically invests these funds
in short-term financial instruments such as overnight U.S. government direct and
agency obligations
 
                                       19
<PAGE>
repurchase agreements, commercial paper rated A-1 and/or P-1 and money market
funds with an underlying credit quality of AA or better, which are subject to
credit risks and interest rate fluctuations. See "Risk Factors -- Investment
Risks." Interest income earned on collected, but unremitted payroll tax funds
amounted to $1.9 million, $5.9 million and $11.5 million for fiscal 1996, 1997
and 1998, respectively. Payroll and payroll tax clients generally are subject to
contracts with an initial term of 36 months. Benefits administration and human
resources software clients generally are subject to contracts with an initial
term of 12 months. The Company's contracts generally do not have significant
penalties for cancellation.
 
    The Company's cost of providing services consists primarily of ongoing
account management, tax and benefits administration operations and production
costs, and, to a lesser extent, amortization of capitalized software development
costs. The Company capitalizes software development costs after technological
feasibility of the software relating to a service has been established and
amortizes such costs using the greater of (i) the straight-line basis over the
estimated useful life of the software, which is generally 36 months, or (ii) the
ratio of current revenue to the total of current revenue and anticipated future
revenue over the life of the related product. General and administrative
expenses consist primarily of personnel costs, professional fees and other
overhead costs for finance and corporate services. Research and development
expenses consist primarily of personnel costs. Client acquisition costs consist
of sales and implementation expenses and, to a lesser extent, marketing
expenses.
 
    The Company has made acquisitions of businesses in the past and intends to
pursue acquisitions in the future. In connection with acquisitions, the Company
has in the past incurred and will likely incur in the future costs associated
with adding personnel, integrating technology, increasing overhead to support
the acquired businesses, acquiring in-process technology and amortizing expenses
related to intangible assets. As a result, such acquisitions have had and any
future acquisition could have an adverse effect on the Company's results of
operations.
 
    In January 1997, the Company acquired all of the outstanding capital stock
of BeneSphere for an initial purchase price of $3.1 million, with up to an
additional $4.5 million to be paid in quarterly installments, beginning April
1998 through January 2000, if certain financial performance conditions are met.
As of June 30, 1998, and in connection with the financial performance
conditions, $2.2 million of the $4.5 additional purchase price had been earned.
In connection with the acquisition of BeneSphere, the Company has recorded $4.5
million of goodwill, which is being amortized ratably over 20 years and could be
increased by up to an additional $2.3 million if additional financial
performance conditions are met. In May 1996, the Company acquired substantially
all of the business and assets of Dimension Solutions for a purchase price of
$1.3 million. In connection with the acquisition of Dimension Solutions, the
Company recorded a one-time charge of $711,000 in fiscal 1996 relating to the
purchase of in-process technology.
 
    As of June 30, 1998, the Company had federal and state net operating loss
carryforwards of approximately $17.2 million and $1.2 million, respectively. The
net operating loss carryforwards will expire at various dates beginning with
fiscal 1999 through 2013, if not utilized. The Company's utilization of the net
operating loss carryforwards may be subject to annual limitations under the
Internal Revenue Code as a result of changes in the Company's ownership, which
limitations could significantly restrict or partially eliminate their
utilization. No income tax expense has been recorded since the Company's
inception.
 
                                       20
<PAGE>
RESULTS OF OPERATIONS
 
    The following table sets forth, for the periods indicated, certain items
reflected in the statements of operations expressed as a percentage of revenue.
There can be no assurance that the indicated trends in revenue growth or
operating results will continue in the future.
 
<TABLE>
<CAPTION>
                                                                                                 YEAR ENDED JUNE 30,
                                                                                           -------------------------------
                                                                                             1996       1997       1998
                                                                                           ---------  ---------  ---------
<S>                                                                                        <C>        <C>        <C>
STATEMENT OF OPERATIONS DATA:
Revenue..................................................................................      100.0%     100.0%     100.0%
Operating expenses:
  Cost of providing services.............................................................       46.4       49.9       51.5
  General and administrative expenses....................................................       14.8       15.6       14.5
  Research and development expenses......................................................        9.1       10.4        9.9
  Client acquisition costs...............................................................       38.9       42.8       38.6
  Acquisition of in-process technology...................................................        5.1     --         --
                                                                                           ---------  ---------  ---------
    Total operating expenses.............................................................      114.3      118.7      114.5
                                                                                           ---------  ---------  ---------
Loss from operations.....................................................................      (14.3)     (18.7)     (14.5)
Interest expense.........................................................................       (3.4)      (4.3)      (1.2)
Other income.............................................................................        0.5        0.2        1.6
                                                                                           ---------  ---------  ---------
Net loss.................................................................................      (17.2)%     (22.8)%     (14.1)%
                                                                                           ---------  ---------  ---------
                                                                                           ---------  ---------  ---------
</TABLE>
 
YEARS ENDED JUNE 30, 1998 AND JUNE 30, 1997
 
    REVENUE.  Revenue increased 69.2% to $46.3 million in fiscal 1998 from $27.4
million in fiscal 1997, primarily due to an increase in the number and average
size of the Company's payroll and tax clients and, to a lesser extent, the
inclusion of a full year's results of the Company's benefits administration
services which were introduced January 1997. Interest income earned on payroll
tax funds invested was $11.5 million and $5.9 million for fiscal 1998 and 1997,
respectively. This increase was primarily the result of higher average daily tax
balances in fiscal 1998.
 
    COST OF PROVIDING SERVICES.  Cost of providing services increased 74.7% to
$23.9 million in fiscal 1998 from $13.7 million in fiscal 1997 and increased as
a percentage of revenue to 51.5% from 49.9%. The increase in absolute dollars
was primarily due to the increase year-over-year in clients serviced. The
increase as a percentage of revenue was primarily due to building management
infrastructure in the Company's benefits operations and the opening of the
Company's production facility in Irvine, California in fiscal 1998.
 
    GENERAL AND ADMINISTRATIVE EXPENSES.  General and administrative expenses
increased 57.1% to $6.7 million in fiscal 1998 from $4.3 million in fiscal 1997
and decreased as a percentage of revenue to 14.5% from 15.6%. The increase in
absolute dollars was primarily due to the hiring of additional management and
administrative personnel to support the Company's growth and, to a lesser
extent, to costs associated with the Company's benefits administration services
which were introduced in January 1997 and included in general and administrative
expenses for the full year of fiscal 1998. The decrease as a percentage of
revenue was due primarily to the allocation of certain fixed costs over higher
revenue.
 
    RESEARCH AND DEVELOPMENT EXPENSES.  Research and development expenses
increased 61.4% to $4.6 million in fiscal 1998 from $2.8 million in fiscal 1997
and decreased as a percentage of revenue to 9.9% from 10.4%. The increase in
absolute dollars was primarily a result of additional personnel and equipment to
develop enhancements and new features to the Company's existing services.
Research and development expenses decreased as a percentage of revenue due in
part to higher revenue and an increase in the amount of expenses capitalized in
fiscal 1998. Capitalized software development costs were $3.9 million and $1.4
million for fiscal 1998 and 1997, respectively.
 
                                       21
<PAGE>
    CLIENT ACQUISITION COSTS.  Client acquisition costs increased 52.6% to $17.9
million in fiscal 1998 from $11.7 million in fiscal 1997 and decreased as a
percentage of revenue to 38.6% from 42.8%. The increase in absolute dollars was
primarily due to the expanded sales and implementation force for payroll and
stand-alone tax services, and inclusion of a full years' expenses related to the
Company's benefits administration services introduced in January 1997.
 
    INTEREST EXPENSE.  Interest expense decreased 53.2% to $557,000 in fiscal
1998 from $1.2 million in fiscal 1997. The decrease in interest expense was
primarily due to the repayment of subordinated debt and repayment of borrowings
under the Company's secured revolving line of credit with proceeds from the
Company's initial public offering in September 1997.
 
    OTHER INCOME.  Other income increased as a percentage of revenue to 1.6% in
fiscal 1998 from 0.2% in fiscal 1997. The increase as a percentage of revenue
was due to higher cash and investment balances resulting from the Company's
initial public offering in September 1997 when compared to the same period the
prior year.
 
YEARS ENDED JUNE 30, 1997 AND JUNE 30, 1996
 
    REVENUE.  Revenue increased 97.5% to $27.4 million in fiscal 1997 from $13.9
million in fiscal 1996, primarily due to an increase in the number and average
size of the Company's payroll clients, the introduction of the Company's payroll
tax service in January 1996 and, to a lesser extent, the introduction of the
Company's benefits administration services in January 1997. Interest income
earned on payroll tax funds invested was $5.9 million and $1.9 million for
fiscal 1997 and 1996, respectively.
 
    COST OF PROVIDING SERVICES.  Cost of providing services increased 112.3% to
$13.7 million in fiscal 1997 from $6.4 million in fiscal 1996 and increased as a
percentage of revenue to 49.9% from 46.4%. The increases were primarily due to
hiring additional managers for payroll account management, operations expense
related to the Company's benefits administration services and, to a lesser
extent, production expenses related to an increase in the number of payroll
clients and increased personnel expenses related to the Company's payroll tax
service, which was introduced in January 1996.
 
    GENERAL AND ADMINISTRATIVE EXPENSES.  General and administrative expenses
increased 108.5% to $4.3 million in fiscal 1997 from $2.1 million in fiscal 1996
and increased as a percentage of revenue to 15.6% from 14.8%. The increases were
primarily a result of the hiring of additional management and administrative
personnel to support the Company's growth.
 
    RESEARCH AND DEVELOPMENT EXPENSES.  Research and development expenses
increased 126.0% to $2.8 million in fiscal 1997 from $1.3 million in fiscal 1996
and increased as a percentage of revenue to 10.4% from 9.1%. The increases were
primarily a result of additional personnel and equipment to develop enhancements
and new features to the Company's existing services. Capitalized software
development costs were $1.4 million in fiscal 1997 and $645,000 in fiscal 1996.
 
    CLIENT ACQUISITION COSTS.  Client acquisition costs increased 117.3% to
$11.7 million in fiscal 1997 from $5.4 million in fiscal 1996 and increased as a
percentage of revenue to 42.8% from 38.9%. The increases were primarily due to
expenses resulting from the establishment of a separate sales force to market
the Company's payroll tax service on a stand-alone basis, increased expenses
resulting from the expansion of the Company's payroll sales force and, to a
lesser extent, implementation expenses related to an increased number of new
clients that started services in January 1997.
 
    INTEREST EXPENSE.  Interest expense increased 151.6% to $1.2 million in
fiscal 1997 from $473,000 in fiscal 1996, primarily due to increased borrowing
under the Company's line of credit, the issuance of promissory notes to certain
investors in October and December 1995 and an increased amount of capitalized
equipment leases.
 
                                       22
<PAGE>
QUARTERLY RESULTS
 
    The following table sets forth selected unaudited quarterly financial
information for each of the eight quarters in the period ended June 30, 1998, as
well as such data expressed as a percentage of the Company's revenue for the
periods presented. This information has been derived from unaudited statements
of operations data that, in the opinion of management, are stated on a basis
consistent with the audited financial statements and include all adjustments
(consisting only of normal recurring adjustments) necessary for a fair
presentation of such information in accordance with generally accepted
accounting principles. The Company's results of operations for any quarter are
not necessarily indicative of the results to be expected in any future period.
<TABLE>
<CAPTION>
                                                                              QUARTER ENDED
                                               ----------------------------------------------------------------------------
                                                         1996                                   1997
                                               ------------------------  --------------------------------------------------
                                                SEPT. 30      DEC. 31     MARCH 31      JUNE 30     SEPT. 30      DEC. 31
                                               -----------  -----------  -----------  -----------  -----------  -----------
                                                                              (IN THOUSANDS)
<S>                                            <C>          <C>          <C>          <C>          <C>          <C>
Revenue......................................   $   4,675    $   5,524    $   8,427    $   8,748    $   9,227    $  10,325
Operating Expenses:
  Cost of providing services.................       2,288        2,950        3,907        4,514        5,019        5,772
  General and administrative expenses........         622          869        1,441        1,350        1,768        1,600
  Research and development expenses..........         625          683          732          801        1,110        1,020
  Client acquisition costs...................       2,215        2,413        3,664        3,414        3,978        4,092
                                               -----------  -----------  -----------  -----------  -----------  -----------
Total operating expenses.....................       5,750        6,915        9,744       10,079       11,875       12,484
                                               -----------  -----------  -----------  -----------  -----------  -----------
Loss from operations.........................      (1,075)      (1,391)      (1,317)      (1,331)      (2,648)      (2,159)
Interest expense.............................        (215)        (305)        (380)        (290)        (255)        (119)
Other income.................................          11            1            2           45           26          234
                                               -----------  -----------  -----------  -----------  -----------  -----------
Net loss.....................................   $  (1,279)   $  (1,695)   $  (1,695)   $  (1,576)   $  (2,877)   $  (2,044)
                                               -----------  -----------  -----------  -----------  -----------  -----------
                                               -----------  -----------  -----------  -----------  -----------  -----------
 
                                                                     AS A PERCENTAGE OF TOTAL REVENUE
                                               ----------------------------------------------------------------------------
Revenue......................................       100.0%       100.0%       100.0%       100.0%       100.0%       100.0%
Operating Expenses:
  Cost of providing services.................        48.9         53.4         46.4         51.6         54.4         55.9
  General and administrative expenses........        13.3         15.7         17.1         15.4         19.2         15.5
  Research and development expenses..........        13.4         12.4          8.7          9.2         12.0          9.9
  Client acquisition costs...................        47.4         43.7         43.4         39.0         43.1         39.6
                                               -----------  -----------  -----------  -----------  -----------  -----------
Total operating expenses.....................       123.0        125.2        115.6        115.2        128.7        120.9
                                               -----------  -----------  -----------  -----------  -----------  -----------
Loss from operations.........................       (23.0)       (25.2)       (15.6)       (15.2)       (28.7)       (20.9)
Interest expense.............................        (4.6)        (5.5)        (4.5)        (3.3)        (2.8)        (1.2)
Other income.................................         0.2          0.0          0.0          0.5          0.3          2.3
                                               -----------  -----------  -----------  -----------  -----------  -----------
Net loss.....................................       (27.4)%      (30.7 )%      (20.1 )%      (18.0 )%      (31.2 )%      (19.8)%
                                               -----------  -----------  -----------  -----------  -----------  -----------
                                               -----------  -----------  -----------  -----------  -----------  -----------
 
<CAPTION>
 
                                                         1998
                                               ------------------------
                                                MARCH 31      JUNE 30
                                               -----------  -----------
 
<S>                                            <C>          <C>
Revenue......................................   $  13,611    $  13,154
Operating Expenses:
  Cost of providing services.................       6,424        6,644
  General and administrative expenses........       1,693        1,666
  Research and development expenses..........       1,213        1,242
  Client acquisition costs...................       5,569        4,219
                                               -----------  -----------
Total operating expenses.....................      14,899       13,771
                                               -----------  -----------
Loss from operations.........................      (1,288)        (617)
Interest expense.............................         (87)         (96)
Other income.................................         242          250
                                               -----------  -----------
Net loss.....................................   $  (1,133)   $    (463)
                                               -----------  -----------
                                               -----------  -----------
 
Revenue......................................       100.0%       100.0%
Operating Expenses:
  Cost of providing services.................        47.2         50.5
  General and administrative expenses........        12.4         12.7
  Research and development expenses..........         9.0          9.4
  Client acquisition costs...................        40.9         32.1
                                               -----------  -----------
Total operating expenses.....................       109.5        104.7
                                               -----------  -----------
Loss from operations.........................        (9.5)        (4.7)
Interest expense.............................        (0.6)        (0.7)
Other income.................................         1.8          1.9
                                               -----------  -----------
Net loss.....................................        (8.3 )%       (3.5 )%
                                               -----------  -----------
                                               -----------  -----------
</TABLE>
 
    Revenue has increased over the last eight quarters primarily as a result of
the increase in the number and average size of the Company's payroll and tax
clients and the introduction of the Company's benefits administration services
in the third fiscal quarter in 1997. The Company's revenue is subject to
significant seasonal fluctuations, with the largest percentage of annual revenue
being realized in the third and fourth fiscal quarters primarily due to new
clients beginning services at the beginning of the tax year in January and
higher interest income earned on tax funds.
 
    The Company's operating expenses typically are higher as a percentage of
revenue in the first and second fiscal quarters as the Company increases
personnel to acquire new clients and to implement and provide services to such
new clients, a large percentage of which begin services in January. The Company
expects this pattern to continue. Cost of providing services increased in the
second and fourth fiscal quarters of 1998 primarily due to increases in account
management personnel and production costs related to the Company's expanded
client base.
 
                                       23
<PAGE>
    The Company's client acquisition costs typically fluctuate from quarter to
quarter in relation to the addition of new clients. Sales, marketing and
implementation costs incurred to provide services to new clients are expensed as
incurred over the implementation period which typically lasts three to nine
months or longer. A significant portion of these costs (including sales
commissions) are expensed at the time clients begin services. In the third
fiscal quarter of 1998, the increase in client acquisition costs in absolute
dollars was primarily due to commission costs and costs for payroll and
stand-alone tax services associated with clients beginning services in January.
 
    The Company's quarterly operating results have in the past and will in the
future vary significantly depending on a variety of factors, including the
number and size of new clients starting services, the decision of one or more
clients to delay or cancel implementation or ongoing services, interest rates,
seasonality, the ability of the Company to design, develop and introduce new
services and features for existing services on a timely basis, transition costs
to new technologies, expenses incurred for geographic expansion, risks
associated with payroll tax and benefits administration services, price
competition, a reduction in the number of employees of its clients, and general
economic factors. Revenue from new clients represents a significant portion of
quarterly revenue in the third and fourth fiscal quarters. A substantial
majority of the Company's operating expenses, particularly personnel and related
costs, depreciation and rent, is relatively fixed in advance of any particular
quarter. The Company's agreements with its clients generally do not have
significant penalties for cancellation. As a result, any decision by a client to
delay or cancel implementation of the Company's services or the Company's
underutilization of personnel may cause significant variations in operating
results in a particular quarter and could result in losses for such quarter. As
the Company secures larger clients, the time required for implementing the
Company's services increases, which could contribute to larger fluctuations in
revenue. Interest income earned from investing payroll tax funds, which is a
significant portion of the Company's revenue, is vulnerable to fluctuations in
interest rates. In addition, the Company's business may be affected by shifts in
the general health of the economy, client staff reductions, strikes,
acquisitions of its client by other companies and other downturns. There can be
no assurance that the Company's future revenue and results of operations will
not vary substantially.
 
LIQUIDITY AND CAPITAL RESOURCES
 
    Since inception, the Company has financed its operations primarily through a
combination of sales of equity securities, private debt and bank borrowings, and
to a lesser extent, equipment leases. Prior to the initial public offering, the
Company raised approximately $23.4 million in private sales of equity securities
and raised approximately $27.0 million from its initial public offering in
September 1997.
 
    At June 30, 1998, the Company had approximately $13.8 million of cash and
cash equivalents and a $20.0 million secured revolving line of credit, which
expires in December 2000. At June 30, 1998, the Company had no outstanding
borrowings under the line of credit. See Note 3 of Notes to Financial
Statements.
 
    Net cash provided by operating activities for fiscal 1998 was $3.6 million
and net cash used in operating activities for fiscal 1997 and 1996 was $4.1
million and $202,000, respectively. Net cash provided by operating activities in
fiscal 1998 compared to net cash used in operating activities in fiscal 1997 was
primarily the result of increases in accrued liabilities, depreciation and
deferred revenue, and decreases in other assets in fiscal 1998, partially offset
by an increase in prepaid expenses and other current assets. The increase in
cash used in operating activities in fiscal 1997 compared to fiscal 1996 was
primarily the result of net losses and, to a lesser extent, increases in
accounts receivable and other assets, partially offset by depreciation and
amortization and an increase in accrued liabilities.
 
    Net cash used in investing activities was $14.3 million, $4.7 million and
$3.3 million for fiscal 1998, 1997 and 1996, respectively. The increase in net
cash used in investing activities in fiscal 1998 resulted primarily from (i)
capital expenditures for equipment, furniture and fixtures to support the
Company's
 
                                       24
<PAGE>
increased personnel, (ii) the move of the Company's corporate headquarters in
early fiscal 1998 and (iii) the establishment of the Company's Irvine production
facility in early fiscal 1998. In addition, the Company capitalized software
development costs of $3.9 million, $1.4 million and $645,000 in fiscal 1998,
1997 and 1996 respectively. The Company expects to make additional capital
expenditures for furniture, equipment and fixtures to support the continued
growth of its operations. In addition, the Company anticipates that it will
continue to expend funds for software development in the future.
 
    Net cash provided by financing activities was $19.5 million, $9.8 million
and $6.7 million for fiscal 1998, 1997 and 1996, respectively. Net cash provided
by financing activities for fiscal 1998 related primarily to $27.0 million of
net proceeds from the Company's initial public offering of common stock and
$959,000 from the exercise of warrants. The increase was partially offset by the
payment of $3.9 million of outstanding subordinated debt and the net repayment
of $4.8 million of borrowings under the Company's secured revolving line of
credit. Net cash provided by financing activities for fiscal 1997 was primarily
a result of $9.9 million of net proceeds from the issuance of preferred stock in
March 1997. Net cash provided by financing activities for fiscal 1996 was
primarily the result of $4.0 million from subordinated debt and net proceeds of
$2.5 million from borrowings under line of credit agreements.
 
    The Company believes that the net proceeds from this Offering, together with
existing cash balances, amounts available under its current credit facility and
anticipated cash flows from operations will be sufficient to meet its working
capital and capital expenditure requirements for at least the next 12 months.
The Company may also utilize cash to acquire or invest in complementary
businesses or to obtain the right to use complementary technologies, although
the Company does not have any pending plans to do so. The Company may sell
additional equity or debt securities or obtain additional credit facilities.
 
YEAR 2000 COMPLIANCE
 
    The Company has conducted a preliminary review of its internal computer
systems to identify the systems that could be affected by the Year 2000 issue
and to develop a plan to make its systems Year 2000 compliant. Based on this
preliminary review, the Company has discovered certain failures to comply with
Year 2000 requirements. The Company is taking action to correct the noncomplying
features of its systems, and the Company believes that its internal software
systems will be Year 2000 compliant by 2000. There can be no assurance, however,
that the Company's systems will be fully Year 2000 compliant in a timely manner,
and a failure by the Company to make its internal systems Year 2000 compliant
could have a material adverse effect on the Company's business, financial
condition and results of operations. The Company has not determined an estimate
of the costs required to correct the noncomplying features, and the Company does
not currently have a contingency plan in the event that it is unable to make its
systems Year 2000 compliant. Additionally, the costs of making such systems Year
2000 compliant could have a material adverse effect on the Company's business,
financial condition and results of operations
 
    The Company believes that its current products are, and future products will
be, fully Year 2000 compliant. The Company's past software products, many of
which are currently used by clients, are not Year 2000 compliant. The Company
has begun the process of transitioning existing clients to its Year 2000
compliant products; however, there can be no assurance that the Company will be
successful in providing all of its clients with Year 2000 compliant products by
2000. Any failure by the Company to transition its clients to Year 2000
compliant products could have a material adverse effect on the Company's
business, financial condition and results of operations. Year 2000 errors or
defects, however, may be discovered in the Company's current and future
products.
 
    The Company is not assessing the Year 2000 compliance of its clients'
systems or the possible effects on its operations of the Year 2000 compliance of
its clients' systems. Due to the substantial integration between the Company's
computer systems and its clients' systems, the failure by the Company's clients
to have Year 2000 compliant systems in a timely manner could have a material
adverse effect on the Company's business, financial condition and results of
operations. The Company is also assessing the
 
                                       25
<PAGE>
possible effects on its operations of the Year 2000 readiness of key suppliers
and subcontractors. The Company's reliance on suppliers and subcontractors, and,
therefore, on the proper functioning of their information systems and software,
means that failure by such suppliers and subcontractors to address Year 2000
issues could have a material adverse effect on the Company's business, financial
condition and results of operations. See "Risk Factors -- Impact of Year 2000
Compliance."
 
INTEREST RATE SWAP AGREEMENTS
 
    During fiscal 1998, the Company entered into various interest rate swap
agreements with a financial institution. The purpose of these agreements is to
convert a portion of the interest the Company earns from collected but
unremitted payroll tax funds from a floating to a fixed rate basis. The Company
considers these agreements to be for "other than trading purposes" and has
accounted for these agreements on an accrual basis, with each net payment or
receipt due or owed under each agreement recognized in earnings during the
period to which the payment or receipt relates, with no recognition on the
balance sheet of the fair value of the agreements. At June 30, 1998, the
aggregate fair value of these agreements was $432,000.
 
    These agreements, with fixed interest rates between 5.736% and 5.905%, each
have a term of two years, one of which has a cancellation option after one year,
and expire at various dates through April 2000. Interest is paid or received
based upon the difference in the fixed interest rate and the contractual
floating rate option times the contractual notional balance. The actual notional
balance varies on a monthly basis due to fluctuations in projected holdings of
collected but unremitted payroll tax funds. At June 30, 1998, the notional
balance was $204.7 million and the average monthly notional balance for the
remaining term of the agreements was $242.0 million. The agreements require
collateral if interest rates increase and certain other conditions are met as
defined in the agreements. At June 30, 1998, no collateral was required.
 
    The primary market risk to which the Company is exposed related to these
agreements is interest rate risk. The Company has performed a sensitivity
analysis related to these agreements assuming both positive and negative
parallel shifts in interest rates of 50, 100 and 150 basis points. As a result
of this analysis, the Company has determined that due to its current use of
interest rate swap agreements, the Company would not experience a material
adverse affect in its business, financial condition and results of operations,
related to such hypothetical changes in interest rates during fiscal 1999. See
"Risk Factors -- Investment Risks."
 
                                       26
<PAGE>
                                    BUSINESS
 
    THE FOLLOWING BUSINESS SECTION CONTAINS FORWARD-LOOKING STATEMENTS THAT
INVOLVE RISKS AND UNCERTAINTIES. THE COMPANY'S ACTUAL RESULTS COULD DIFFER
MATERIALLY FROM THOSE ANTICIPATED IN THESE FORWARD-LOOKING STATEMENTS AS A
RESULT OF CERTAIN FACTORS, INCLUDING THOSE SET FORTH UNDER "RISK FACTORS" AND
ELSEWHERE IN THIS PROSPECTUS.
 
OVERVIEW
 
    ProBusiness is a leading provider of employee administrative services for
large employers. The Company's primary service offerings are payroll processing,
payroll tax filing, benefits administration, including the enrollment and
processing of flexible benefit plans and COBRA programs, and human resources
software. The Company's proprietary PC-based payroll system offers the
cost-effective benefits of outsourcing and high levels of client service, while
providing the flexibility, control, customization and integration of an in-house
system. As of June 30, 1998, the Company provided services to approximately
1,400 clients. As of June 30, 1998, the Company provided payroll processing
services to approximately 510 clients with an aggregate of approximately 575,000
active employees and an average of approximately 1,100 employees. For the
quarter ended June 30, 1998, the Company processed 4.3 million checks for the
Company's payroll clients. In addition to providing tax filing services for its
payroll clients, as of June 30, 1998 the Company provided stand-alone tax filing
services to 72 clients with an aggregate of more than 1.1 million employees and
an average of more than 15,000 employees.
 
    The Company differentiates itself from its competitors through its
proprietary PC-based technology, high quality, responsive and professional
client service, and focus on the needs of large employers. ProBusiness develops
a business partnership with each client by assessing each client's payroll
processing needs, reengineering and designing the client's payroll systems and
processes and implementing a cost-effective solution. The Company maintains an
ongoing relationship with each client using a strategic team of specialists led
by a personal account manager who proactively manages each client's account and
marshals the resources of the team to meet the client's specific needs.
ProBusiness maintains a low client-to-account manager ratio to offer clients
accessible and responsive account management. The Company believes that its low
client-to-account manager ratio and its focus on client service are key factors
in enabling the Company to achieve a high payroll client retention rate, which
was approximately 92% for fiscal year 1998.
 
INDUSTRY BACKGROUND
 
    Many large businesses have found that outsourcing non-core functions reduces
costs, improves service, quality and efficiency, allows personnel to focus on
core competencies and enhances productivity through access to advanced
technologies. As a result, the demand for outsourcing employee administrative
services has grown significantly and is expected to continue to grow over the
next several years. According to G-2 Research, Inc., third-party payroll
processing, payroll tax filing and benefits administration is expected to
generate approximately $3.9 billion in revenue in 1998 and approximately $9.3
billion in revenue in 2003.
 
    Payroll processing, payroll tax filing and benefits administration lend
themselves to outsourcing because both are complex and costly for employers to
conduct internally. Payroll processing involves tracking employee data,
calculating payroll data and producing paychecks and direct deposits, remitting
and filing payroll taxes and generating management reports. Benefits
administration consists of many human resources functions, such as the
enrollment and processing of flexible benefits plans and the administration and
management of COBRA programs. In recent years, payroll processing and benefits
administration have increased in complexity due to continual changes in
regulations and increasingly sophisticated employee benefit plans. For example,
large employers must have the ability to calculate taxes for multiple federal,
state and local government agencies, collect garnishments based on different
state laws and make numerous agency filings. In addition, payroll and benefits
administration systems must keep
 
                                       27
<PAGE>
pace with rapidly evolving business operations as companies increase in size,
expand geographically or add new operations. Finally, these systems must be
flexible and scalable to integrate with increasingly advanced computer systems
as companies adopt new technologies.
 
    Despite the complexities of payroll processing and the advantages provided
by outsourcing, most large employers continue to process payroll in-house
because they believe their unique business needs require the control and
integration of an in-house system. These in-house payroll systems generally run
on expensive mainframe or minicomputer systems and require customization and
significant ongoing technical support. In addition, such systems typically are
operated and maintained by large payroll departments, which are supported by
dedicated programmers, systems analysts and production personnel. As their
payroll needs change, employers that process their payroll in-house must
continue to make significant investments in personnel, hardware and software to
maintain and upgrade their payroll systems.
 
    Large employers that have outsourced their payroll processing needs have
looked primarily to traditional payroll service providers, which process payroll
data received from clients utilizing mainframe computers located at multiple
regional data centers. This approach utilizes two systems, the client's and the
service provider's, which have different hardware, operating systems, software
applications and data configurations. Maintaining and synchronizing two separate
systems makes it difficult for these service providers to update code, add
features and functionality and provide clients with customization and
integration with their other systems. In addition, the complexities presented by
operating two separate systems often impede the timely identification and
resolution of client payroll processing problems.
 
    Many large employers that choose to outsource their employee administration
functions require a payroll provider that offers a high level of flexibility and
client service. In addition, these employers prefer to have a single service
provider of comprehensive and integrated services for their payroll, benefits
and other employee administrative needs. Given the inherent limitations of the
technology used by traditional payroll processing providers, such providers are
unable to deliver a highly responsive and flexible solution. As a result, the
Company believes a significant opportunity exists for service providers that can
furnish large employers with high quality client service and a payroll system
that offers the cost-effective benefits of outsourcing, while providing the same
level of control, customization and integration as an in-house system.
 
THE PROBUSINESS SOLUTION
 
    The Company's solution provides large employers with the cost-effective
benefits of outsourcing and high levels of client service, while providing the
flexibility, system control, customization and integration of an in-house
system. The Company combines its PC-based technology and personalized client
service to provide a broad range of service offerings, including payroll
processing, payroll tax filing, benefits administration and human resources
software.
 
    PC-BASED TECHNOLOGY.  The Company's proprietary PC-based technology for its
payroll services provides a platform for delivering high levels of service
together with the flexibility and control of an in-house system. The Company
creates a mirrored version of each client's system, which allows the Company's
account managers to access client information using the same data, programs and
screens as the client uses on its PC network. This enables the Company to
quickly and easily identify client problems or modify application programs in
response to client requests. The client maintains control by having direct
access to all calculation programs and all historical and transactional data,
which also provides the client with flexibility to respond quickly to employee
and third-party inquiries, to fully analyze payroll data and to generate
management reports.
 
    The Company's system architecture is designed to distribute payroll
processing tasks to multiple low cost, high performance PCs, which enables the
Company to scale its system continually to handle increasing transaction
volumes. The Company's PC-based application software supports the development of
customized solutions for each client that can be easily upgraded and integrated
with a client's other
 
                                       28
<PAGE>
systems. In addition, multiple networked PCs facilitate exception processing and
rapid response that large employers require.
 
    CLIENT SERVICE FOCUS.  The Company delivers high quality, responsive and
professional service by establishing a business partnership with each client.
The Company assigns each client a personal account manager, who proactively
manages the account and marshals the resources of a strategic team of
specialists to meet the client's specific needs. The Company maintains a low
client-to-account manager ratio to offer clients accessible and responsive
account management. The Company supports each client with functional and
regulatory expertise in payroll, payroll tax and employee benefits, as well as
specialists in pay data interfaces, general ledger interfaces, paid-time-off,
report writing and systems integration. The Company uses its systems integration
expertise to facilitate the integration of its payroll processing system with
the client's existing hardware and software. To support and provide high quality
service, the Company focuses on hiring experienced accounting and technical
professionals from the payroll, accounting, human resources and financial
services industries. The Company promotes its client service culture by
instilling a sense of ownership in each employee through incentive compensation
and recognition of achievements based on providing high quality service to
clients.
 
    VALUE-ADDED SERVICES.  The Company believes that it provides its clients
higher value-added and more cost-effective payroll services than most other
third-party providers. During the implementation process, the Company
reengineers the client's payroll processes and designs a payroll system that
integrates with the client's other systems. Once implementation is completed,
integration between payroll and other systems is improved, eliminating manual
tasks and allowing a client to redeploy specialized personnel to other functions
within the organization.
 
STRATEGY
 
    The Company's objective is to be the premier provider of employee
administrative services for large employers. The Company's strategy is to
continue providing clients with high levels of personal service and developing a
comprehensive and fully integrated suite of employee administrative services.
The Company also intends to expand its client base and provide additional
services to its existing clients. The Company's ongoing strategy includes the
following key factors:
 
    PROVIDE PREMIER SERVICE.  The Company is committed to providing high levels
of personal service and proactive account management, including maintaining a
low client-to-account manager ratio. The Company believes that its ability to
consistently deliver high quality service is a competitive advantage in the
large employer market and is a key factor in enabling the Company to achieve a
high payroll client retention rate, which was approximately 92% for fiscal year
1998.
 
    EXPAND CLIENT BASE.  The Company intends to continue adding to its client
base by expanding its direct sales force and locating sales representatives in
major metropolitan areas throughout the United States, as well as increasing its
penetration in existing markets and pursuing strategic alliances and
acquisitions.
 
    PROVIDE A COMPREHENSIVE AND INTEGRATED SOLUTION.  The Company's goal is to
create a single data processing system that it can use as a platform to offer a
full range of services to clients, thereby strengthening client relationships
and improving efficiencies for both the Company and its clients. The Company
intends to continue investing substantial resources to further develop a
comprehensive and fully integrated suite of employee administrative services and
extend the functionality of its existing proprietary technology.
 
    INCREASE SERVICES TO EXISTING CLIENTS.  The Company believes that there is a
significant opportunity for it to cross-sell its services to its existing client
base, as few of its current clients use all of the Company's
 
                                       29
<PAGE>
services. In addition, the Company intends to leverage its relationships with
existing clients to market new services and features.
 
    PURSUE STRATEGIC ACQUISITIONS AND ALLIANCES.  The Company intends to pursue
acquisitions and alliances to broaden its range of services and service
features, enhance industry and technical expertise and acquire complementary
technology. For example, during fiscal 1996, the Company introduced its human
resources software and, during fiscal 1997, its benefits administration services
through the acquisitions of Dimension Solutions and BeneSphere, respectively.
During 1998, the Company formed alliances with SAP AG, a leading provider of
enterprise business solutions, and Sheakly UniService, a leading provider of
unemployment cost control services. See "-- Sales and Marketing."
 
    EXTEND TECHNOLOGY LEADERSHIP.  The Company is committed to investing
resources to enhance its industry-leading employee administrative services
technology. The Company is developing a client/server version of its system and
is broadening its administrative services offerings by developing Internet-based
applications. The Company believes that the introduction of such administrative
services offerings will enable it to address the growing demand for the
extension of its applications throughout the enterprise.
 
    The Company's strategy involves substantial risks and uncertainties. There
can be no assurance that the Company will be successful in implementing its
strategy or that its strategy, even if implemented, will lead to successful
achievement of the Company's objectives. If the Company is unable to implement
its strategy effectively, the Company's business, financial condition and
results of operations will be materially adversely affected. See "Risk Factors."
 
SERVICE OFFERINGS
 
    The Company provides a broad range of employee administrative services,
including payroll processing, tax filing, benefits administration and human
resources software. The Company intends to expand its service offerings through
future acquisitions, alliances and investments and to develop enhancements to
its existing services internally.
 
    PAYROLL PROCESSING.  The Company processes time and attendance data to
calculate and produce employee paychecks, direct deposits and reports for its
clients. Clients receive paychecks and reports within 24 to 48 hours of the
Company's receipt of the data electronically submitted from the client. The
Company's system is highly configurable to meet the specialized needs of each
client yet maintains the ability to provide high volume processing. The system
integrates easily with the client's general ledger, human resources and time and
attendance systems. In addition, the Company offers many sophisticated features,
including the automatic enrollment and tracking of paid time off, proration of
compensation for new hires and integrated garnishment processing.
 
    PAYROLL TAX FILING.  The Company collects contributed employer and employee
tax funds from clients, deposits such funds with tax authorities when due, files
all tax returns and reconciles the client's account. The Company will also
represent the client before tax authorities in disputes or inquiries.
Substantially all existing payroll clients utilize the Company's payroll tax
service. In addition, as of June 30, 1998, the Company provided stand-alone tax
services to 72 clients with an aggregate of more than 1.1 million employees and
an average of more than 15,000 employees.
 
    BENEFITS ADMINISTRATION.  The Company's benefits administration services
include flexible benefits enrollment and processing, COBRA administration and
consolidated billing and eligibility tracking. Employees can enroll in and
choose their flexible spending benefits through traditional paper-based forms or
through Internet-accessible enrollment sites using the Company's Enrollnet-TM-
service.
 
    HUMAN RESOURCES SOFTWARE.  The Company's human resources software tracks and
reports general employee information, including compensation, benefits, skills,
performance, training, job titles and
 
                                       30
<PAGE>
medical history. For clients that also use the Company's payroll service, the
human resources data can be transferred to the payroll services system, thus
eliminating the need for duplicate data entry.
 
    The Company continually evaluates the addition of add-on service offerings
to expand the breadth of its solution through alliances, acquisitions or
internal development. Such additional services include administrative services
related to time and attendance, stock, travel and entertainment, unemployment
insurance and 401(k) plans.
 
CLIENT SERVICE
 
    The Company believes that its focus and dedication to providing high levels
of client service is a competitive advantage in the large employer market.
ProBusiness develops a business partnership with each client by assessing each
client's payroll processing needs, reengineering and designing the client's
payroll system and process and implementing a value-added solution. The Company
maintains an ongoing relationship with each client using a strategic team that
includes a sales representative, a sales analyst, an implementation manager, an
account manager and numerous functional, regulatory and technical support
specialists. The Company intends to continue providing its clients with a high
level of service by hiring professionals who are experienced in their fields.
Most service personnel have experience in payroll, accounting, human resources
or financial services industries, and many hold Certified Public Accountant or
Certified Payroll Professional accreditations.
 
    The Company continually monitors the quality of its service through client
feedback mechanisms. The Company obtains valuable insights into the needs of its
clients through its partnership with each client and from client responses to
surveys, which are conducted semi-annually. The Company uses this information to
help develop, identify and optimize new service offerings provided to existing
clients and improve the level of service provided to clients. The Company also
uses client feedback as a basis for incentive compensation and recognition of
achievements.
 
    SALES.  The Company believes that client service begins with the sales
process. A sales representative and a sales analyst work together to assess a
potential client's payroll processing needs. Based on this assessment, the sales
team then identifies opportunities to reengineer the prospective client's
payroll processes and to design a payroll solution that integrates effectively
with its other systems. The payroll sales cycle typically ranges from three to
twelve months or longer.
 
    IMPLEMENTATION.  Upon engagement by a client, the Company assigns a team of
technical support specialists, headed by an implementation manager who leads the
transition from the client's former payroll system to the Company's system. The
implementation manager works with the client, the sales analyst and technical
support specialists to integrate the Company's payroll system with the client's
other systems and to customize the system to improve the client's payroll
processes. The Company uses its systems integration expertise to facilitate the
integration of its payroll processing system with the client's existing hardware
and software. The implementation process generally takes three to nine months or
longer, depending on the complexity of the client's payroll processes and
systems and the size of the client.
 
    ACCOUNT MANAGEMENT.  An account manager is assigned to each client during
the implementation process and serves as the client's day-to-day contact at the
Company. The account manager coordinates the efforts of the Company's
functional, regulatory and technical support specialists as necessary. The
account manager visits each client regularly and establishes an annual business
plan with the client that details scheduled payroll events such as open
enrollment periods for employee benefits plans or software system changes. This
annual business plan allows the Company to provide clients with uninterrupted
payroll services during these periods. Account managers use the Company's
proprietary CallLog system to record and track all client calls, record client
feedback and help ensure that the client's needs are addressed promptly and
thoroughly. The Company maintains a low client-to-account manager ratio to offer
clients accessible and responsive account management.
 
                                       31
<PAGE>
    SUPPORT SPECIALISTS.  The Company supports each client with functional and
regulatory specialists in payroll, payroll tax and employee benefits, as well as
pay data interfaces, general ledger interfaces, paid-time-off, report writing
and system integration. Each of these specialists is available to speak directly
with clients as needed, meet with clients onsite or support clients indirectly
through the account manager.
 
TECHNOLOGY
 
    The Company's proprietary PC-based technology for its payroll services
provides a platform for delivering high levels of service together with the
flexibility and control of an in-house system. The Company creates a mirrored
version of each client's system, which allows the Company's account managers to
access client information using the same data, programs and screens as the
client uses on its PC network. This enables the Company to quickly and easily
identify client problems or modify application programs in response to client
requests. The client maintains control by having direct access to all
calculation programs and all historical and transactional data, which also
provides the client with flexibility to respond quickly to employee and
third-party inquiries, to fully analyze payroll data and to generate management
reports. The Company's intuitive Windows-based interface makes navigation simple
and allows new users to be trained quickly. The Company is developing a new
suite of online self-service administrative services applications accessible
through the Internet that enable clients' employees to view paychecks and other
compensation and benefits data.
 
    The Company's system architecture is designed to distribute payroll
processing tasks to multiple low cost, high performance PCs, which enables the
Company to scale its system continually to handle increasing transaction
volumes. The Company's PC-based application software supports the development of
customized solutions for each client that can be easily upgraded and integrated
with a client's other systems. In addition, multiple networked PCs facilitate
exception processing and rapid response that large employers require.
 
                                       32
<PAGE>
CLIENTS
 
    The Company targets large companies with complex and changing business needs
in diverse industries. As of June 30, 1998, the Company provided services to
approximately 1,400 clients. Of these clients, approximately 510 were payroll
processing clients, with an aggregate of approximately 575,000 active employees
and an average of approximately 1,100 employees. For the quarter ended June 30,
1998, the Company processed 4.3 million payroll checks for the Company's payroll
clients. The Company began providing stand-alone tax filing services to clients
in 1996 and, as of June 30, 1998, provided these services to 72 clients with an
aggregate of more than 1.1 million employees and an average of more than 15,000
employees. Substantially all existing payroll clients utilize the Company's
payroll tax filing service. For fiscal 1998, no client accounted for more than
4% of the Company's revenue. Set forth below is a representative list of the
Company's clients, from each of which the Company recognized revenue of at least
$25,000 in fiscal 1998.
 
<TABLE>
<CAPTION>
TECHNOLOGY                        CONSUMER AND RETAIL            FINANCIAL SERVICES
- --------------------------------  -----------------------------  ---------------------------
<S>                               <C>                            <C>
3Com Corporation                  Airtouch Communications, Inc.  California Casualty Group
Advanced Micro Devices, Inc.      Amoco Corporation              E*TRADE Group, Inc.
Ascend Communications, Inc.       Childrens Discovery Centers    First Allmerica Financial
AST Research, Inc.                of                             Life
Atmel Corporation                 America, Inc.                  Insurance Company
Bay Networks Inc.                 Coach Leatherwear Co., Inc.    North American Title
Cadence Design Systems Inc.       Dollar General Corporation     Insurance Company
Cisco Systems Inc.                Esprit de Corp.                U.S. Bancorp
Dell Computer Corporation         The Gap, Inc.                  OTHER
First Data Corporation            The Gillette Company           Abbott Laboratories
Fujitsu, Ltd.                     J. C. Penney Company, Inc.     Allergan, Inc.
Hitachi America Ltd               Koll Management Services,      CCH Incorporated
Informix Corporation              Inc.                           Clubcorp International
Integrated Device Technology,     Michaels Stores, Inc.          Federal Express Corporation
Inc.                              Natural Wonders, Inc.          Pharmacia & Upjohn, Inc.
Intuit Inc.                       St. John Knits Inc.            Raychem Corporation
KLA/Tencor Corporation            Sunglass Hut                   Watkins-Johnson Company
LSI Logic Corporation             International, Inc.
Netscape Communications Corp.     Toyota Motor Corporation
Newbridge Networks, Inc.          U.S. Computer Services
Novell, Inc.                      Williams-Sonoma, Inc.
Oracle Corporation                Ziff Davis Publishing Company
Pacific Scientific Company        FOOD PRODUCTS AND SERVICES
Quantum Corporation               BonAppetit Management
Read-Rite Corporation             Company
Siemens Business Communication    Fresh Choice, Inc.
 Systems, Inc.                    Kellogg USA Inc.
Silicon Graphics, Inc.            OreIda Foods Inc.
Silicon Systems, Inc.             Pacific Coast Producers
Solectron Corporation             Specialty Restaurants Corp.
Storage Technology Corporation
Sybase, Inc.
VeriFone, Inc.
</TABLE>
 
    The Company believes that its low client-to-account manager ratio and its
focus on client service are key factors in enabling the Company to achieve a
high payroll client retention rate, which was approximately 92% for fiscal 1998.
Historically, the Company's client retention rates have been negatively
 
                                       33
<PAGE>
impacted primarily due to clients ceasing to use the Company's services
following a merger or sale of the client. The Company does not have long-term
contracts with its clients, and the Company's existing contracts do not have
significant penalties for cancellation.
 
SALES AND MARKETING
 
    The Company employs a direct sales force to gain new payroll and payroll tax
clients and increase the number of services provided to existing clients. The
Company currently targets large employers through direct marketing, trade shows
and active participation in local chapters of the American Payroll Association.
The Company uses a team selling approach, whereby sales analysts and sales
representatives collaborate to assess a potential client's needs and develop a
cost-effective solution. The payroll sales cycle typically ranges from three to
twelve months or longer. The Company primarily utilizes insurance brokers to
attract new benefits administration clients.
 
    The Company seeks to attract and retain experienced industry sales
representatives. The Company believes that its long-term competitiveness depends
on increasing further its national presence. The Company believes that
continuing to add direct sales representatives in major metropolitan areas
throughout the United States is the most effective means of increasing its
national client base. Over the past two years, the Company has added sales and
implementation representatives covering major metropolitan areas, including
Atlanta, Chicago, Dallas, New York and Seattle. To support its sales growth in
the eastern United States, the Company intends to open a satellite sales and
implementation center in New Jersey during the fourth quarter of calendar 1998.
 
    The Company's marketing department provides support materials and marketing
communications to sales representatives, promotes public relations, conducts
direct mail campaigns, manages trade show participation, and develops and
manages corporate Web sites.
 
    As part of its strategy to provide a comprehensive suite of employee
administrative services, the Company has recently entered into strategic
alliances with two industry leaders. The Company has formed an alliance with SAP
AG, a leading provider of enterprise business solutions, to offer customers high
levels of flexibility in managing payroll and payroll tax processes by linking
the Company's payroll and tax solution to SAP's HR System. The Company has also
formed an alliance to provide services to clients jointly with Sheakly
UniService, a leading provider of unemployment cost control services.
 
RESEARCH AND DEVELOPMENT
 
    The Company intends to continue investing substantial resources to further
develop a comprehensive and fully integrated suite of employee administrative
services and extend the functionality of its proprietary payroll processing
systems. For example, the Company is developing a new suite of online
self-service administrative services applications accessible through the
Internet that enable clients' employees to view paychecks as well as other
compensation and benefits data. In addition, the Company expects to introduce an
integrated payroll and human resources system utilizing client/server technology
that will run on Windows 95 and Windows NT.
 
    The foregoing information contains forward-looking statements that involve
risks and uncertainties. Actual events could differ materially from those
anticipated in these forward-looking statements, as a result of certain factors
including those discussed in the paragraph below. See "Risk Factors -- Reliance
on Rapidly Changing Technology; Risks of Software Defects."
 
COMPETITION
 
    The market for the Company's services is intensely competitive, subject to
rapid change and significantly affected by new service introductions and other
market activities of industry participants. The Company primarily competes with
several public and private payroll service providers such as Automatic
 
                                       34
<PAGE>
Data Processing, Inc., Ceridian Corporation and Paychex, Inc., as well as
smaller, regional competitors. Many of these companies have longer operating
histories, greater financial, technical, marketing and other resources, greater
name recognition and a larger number of clients than the Company. In addition,
certain of these companies offer more services or features than the Company and
have processing facilities located throughout the United States. The Company
also competes with in-house employee services departments and, to a lesser
extent, banks and local payroll companies. With respect to benefits
administration services, the Company competes with insurance companies, benefits
consultants and other local benefits outsourcing companies. The Company may also
compete with marketers of related products and services that may offer payroll
or benefits administration services in the future. The Company has experienced,
and expects to continue to experience, competition from new entrants into its
markets. Increased competition could result in pricing pressures, loss of market
share and loss of clients, any of which could have a material adverse effect on
the Company's business, financial condition and results of operations.
 
    The Company believes that the principal competitive factors affecting its
market include client service, system functionality and performance, system
scalability, reputation, system cost and geographic location. The failure of the
Company to compete successfully would have a material adverse effect on the
Company's business, financial condition and results of operations.
 
PROPRIETARY RIGHTS
 
    The Company's success is dependent in part upon its proprietary software
technology. The Company relies on a combination of contract, copyright and trade
secret laws to establish and protect its proprietary technology. The Company has
no patents, patent applications or registered copyrights. The Company
distributes its services under software license agreements that grant clients
licenses to use the Company's services and contain various provisions protecting
the Company's ownership and the confidentiality of the underlying technology.
The Company generally enters into confidentiality and/or license agreements with
its employees and existing and potential clients, and limits access to and
distribution of its software, documentation and other proprietary information.
There can be no assurance that the steps taken by the Company in this regard
will be adequate to deter misappropriation or independent third-party
development of the Company's technology.
 
    There can be no assurance that the Company's services and technology do not
infringe any existing patents, copyrights or other proprietary rights or that
third parties will not assert infringement claims in the future. If any such
claims are asserted and upheld, the costs of defense could be substantial and
any resulting liability to the Company could have a material adverse effect on
the Company's business, financial condition and results of operations. See "Risk
Factors -- Reliance on Rapidly Changing Technology; Risks of Software Defects."
 
EMPLOYEES
 
    As of June 30, 1998, the Company had 500 full-time employees. The Company
believes that its relations with its employees are good.
 
FACILITIES
 
    The Company's headquarters are located in Pleasanton, California and consist
of approximately 130,000 square feet of office space leased through September
2008. The Company has signed a lease for a building to be built adjacent to its
headquarters which will consist of approximately 70,000 square feet upon its
planned completion in mid-1999.
 
    The Company also has a sales, implementation and production facility and a
back-up payroll facility in Irvine, California, where it leases approximately
14,000 square feet under a lease which terminates May 2002. The Company is
currently negotiating a lease for a satellite sales and implementation center in
New Jersey.
 
                                       35
<PAGE>
    The Company's benefits administration processing operations are located in
Bellevue, Washington, where the Company leases approximately 6,500 square feet
under a lease that will terminate in June 2003. The Company is currently
negotiating a lease for a new building in Bellevue to house the Company's
benefits administration processing operations. Such lease is expected to
commence in early 1999.
 
    The Company believes that its existing facilities are adequate for its
current needs and that additional facilities can be leased to meet future needs.
 
                                       36
<PAGE>
                                   MANAGEMENT
 
EXECUTIVE OFFICERS AND DIRECTORS
 
    The following table sets forth certain information with respect to the
executive officers and directors of the Company as of August 1, 1998.
 
<TABLE>
<CAPTION>
NAME                                                        AGE                          POSITION
- ------------------------------------------------------      ---      ------------------------------------------------
<S>                                                     <C>          <C>
Thomas H. Sinton......................................          50   Chairman of the Board, President, Chief
                                                                      Executive Officer, Director
Jeffrey M. Bizzack....................................          38   Senior Vice President, Sales
Leslie A. Johnson.....................................          49   Senior Vice President, Client Services and Chief
                                                                      Service Officer
Steven E. Klei........................................          38   Senior Vice President, Finance, Chief Financial
                                                                      Officer and Secretary
Robert E. Schneider...................................          40   Senior Vice President, Product Development and
                                                                      Chief Technical Officer
William T. Clifford(1)................................          52   Director
David C. Hodgson(2)...................................          41   Director
Ronald W. Readmond(1)(2)..............................          55   Director
Thomas P. Roddy(1)....................................          63   Director
</TABLE>
 
- ------------------------
 
(1) Member of the Audit Committee.
 
(2) Member of the Compensation Committee.
 
    MR. SINTON, founder of the Company, has served as a Director of the Company
since the Company's incorporation in October 1984, and from March 1993 to
present, Mr. Sinton has served as the President and Chief Executive Officer of
the Company. Since December 1996 and for a period between September 1989 and
February 1993, Mr. Sinton served as Chairman of the Board. Mr. Sinton holds a
B.A. degree in English Literature, MAGNA CUM LAUDE, from Harvard University, an
M.S. degree in Food Science from the University of California at Davis and an
M.B.A. degree from Stanford University. Mr. Sinton received a Fulbright
Fellowship to study at the University of Vienna in Vienna, Austria.
 
    MR. BIZZACK has served as Senior Vice President, Sales of the Company since
July 1993. From October 1992 to July 1993, Mr. Bizzack served as Vice President,
Sales of the Company. From October 1988 to October 1992, Mr. Bizzack served as a
District Sales Manager of the Company. Mr. Bizzack attended Saint Mary's
College.
 
    MS. JOHNSON has served as Senior Vice President, Client Services and Chief
Service Officer of the Company since August 1997 and served as Vice President,
Client Services of the Company from September 1993 to August 1997. From May 1992
to September 1993, Ms. Johnson was Director, National Accounts for Automatic
Data Processing. From January 1976 until her division was acquired by Automatic
Data Processing in May 1992, Ms. Johnson held several positions at BankAmerica
Corporation, most recently as Vice President, Northern California National
Accounts. Ms. Johnson holds a B.A. degree in Communications from the University
of Colorado.
 
    MR. KLEI has served as Senior Vice President, Finance of the Company since
August 1997, as Chief Financial Officer of the Company since July 1995 and as
Secretary of the Company since August 1996. Mr. Klei served as Vice President,
Finance from July 1995 to August 1997. From April 1993 to July 1995, Mr. Klei
was Corporate Controller for Esprit de Corp, an apparel company. From December
1990 to April 1993, Mr. Klei provided consulting services to financially
troubled companies based on his experience at New Home Interiors, a regional
operator of showrooms for home products and services. In such capacity, Mr. Klei
joined Rainbow Records ("Rainbow"), a retailer of records and videos, as a
consultant
 
                                       37
<PAGE>
in December 1990 at which time Rainbow was contemplating a liquidation. Mr. Klei
presided over the orderly liquidation of Rainbow as Chief Financial Officer from
April 1991 to February 1992. Subsequently, Rainbow entered into involuntary
bankruptcy and received final approval from the bankruptcy court in the Northern
District of California in Oakland. Mr. Klei holds a B.S. degree in Accounting
from Central Michigan University and is a Certified Public Accountant.
 
    MR. SCHNEIDER has served as Senior Vice President, Product Development and
Chief Technical Officer of the Company since August 1997 and served as Vice
President, Research and Development and Chief Technical Officer of the Company
from November 1996 to August 1997. From April 1995 to July 1996, Mr. Schneider
served as Senior Vice President of Product Development at Premenos Technology
Corporation, an electronic commerce software company. From February 1989 to
March 1995, Mr. Schneider held several positions at Sybase Inc., most recently
as Vice President and Business Unit Manager of the Server Products Group. Mr.
Schneider holds a B.S. degree in Computer Science from the University of San
Francisco.
 
    MR. CLIFFORD has served as a Director of the Company since August 1997. Mr.
Clifford has been the President of Gartner Group Research and the Chief
Operating Officer of Gartner Group, Inc. since April 1995 and Executive Vice
President, Operations of Gartner Group, Inc. since October 1993. From December
1988 to October 1993 Mr. Clifford held various positions at Automatic Data
Processing, Inc., including President of National Accounts and Corporate Vice
President, Information Services. Mr. Clifford holds a B.A. degree in Economics
from the University of Connecticut.
 
    MR. HODGSON has served as a Director of the Company since March 1997. Mr.
Hodgson is a Managing Member of General Atlantic Partners LLC ("GAP LLC") and
has been with GAP LLC since 1982. Mr. Hodgson is also a director of Baan
Company, N.V., a publicly-traded software company, Walker Interactive, a
publicly-traded software company, and several other privately-held software
companies, in which GAP LLC or one of its affiliates is an investor. Mr. Hodgson
holds an A.B. degree in Mathematics from Dartmouth College and an M.B.A. degree
from Stanford University.
 
    MR. READMOND has served as a Director of the Company since February 1997.
Since June 1998, Mr. Readmond has been President and Chief Operating Officer of
Wit Capital Group Incorporated and has been an advisor of Barbour Griffith &
Rogers, a lobbying firm, and Chairman of International Equity Partners, L.P., a
private equity and project development company since January, 1997. From August
1989 to December 1996, Mr. Readmond held various positions at Charles Schwab &
Co. Inc., most recently serving as Vice Chairman. Mr. Readmond holds a B.A.
degree in Economics from Western Maryland College.
 
    MR. RODDY has served as a Director of the Company since 1992. Since 1988,
Mr. Roddy has served as President and Chief Executive Officer of Lafayette
Investments Inc., an investment banking and investment advisory company. Mr.
Roddy holds a B.S. degree in Biochemistry from Villanova University.
 
    Mr. Hodgson was nominated and elected as a Director of the Company pursuant
to an agreement entered into between the Company, GAP LLC and Thomas H. Sinton
and his affiliates, in connection with the sale of Preferred Stock by the
Company to GAP LLC. Under such agreement, GAP LLC and Mr. Sinton and his
affiliates agreed to vote their shares to elect one director to the Board of
Directors designated by GAP LLC until the third annual meeting of stockholders
after the Company's initial public offering.
 
    The Board of Directors presently consists of five members who hold office
until the annual meeting of stockholders or until a successor is duly elected
and qualified. The Board of Directors is divided into three classes. One class
of directors is elected annually and its members hold office for a three-year
term or until their successors are duly elected and qualified, or until their
earlier removal or resignation. The number of directors may be changed by a
resolution of the Board of Directors. Executive officers are elected by the
 
                                       38
<PAGE>
Board of Directors. There are no family relationships among any of the directors
and executive officers of the Company.
 
    The Board of Directors has established an Audit Committee and a Compensation
Committee. The Audit Committee recommends the engagement of auditors and reviews
the results and scope of the audit and other services provided by the Company's
independent auditors, reviews and evaluates the Company's control functions and
reviews the Company's investment policy. The Compensation Committee makes
recommendations to the Board of Directors concerning salaries and incentive
compensation for employees and consultants of the Company. The Compensation
Committee also administers the Company's 1996 Stock Option Plan and 1997
Employee Stock Purchase Plan. See "-- Stock Plans."
 
DIRECTOR COMPENSATION
 
    Members of the Company's Board of Directors do not receive compensation for
their services as directors. Certain directors have been granted options to
purchase Common Stock in the past, and options may be granted to Directors of
the Company in the future. Mr. Clifford, Mr. Hodgson, Mr. Roddy and Mr. Readmond
have received options to purchase 22,500, 22,500, 93,750, and 22,500 shares,
respectively, of the Company's Common Stock, at exercise prices ranging from
$0.16 to $6.00 per share.
 
EXECUTIVE COMPENSATION
 
    The following table sets forth the compensation paid to (i) the Chief
Executive Officer and (ii) the Company's four other most highly compensated
executive officers (collectively with the Chief Executive Officer, the "Named
Executive Officers") for services rendered in all capacities to the Company
during the fiscal years ended June 30, 1997 and June 30, 1998.
 
                           SUMMARY COMPENSATION TABLE
 
<TABLE>
<CAPTION>
                                                                                                         LONG-TERM
                                                                                                       COMPENSATION
                                                                                                         AWARDS(1)
                                                                                                       -------------
                                                                                ANNUAL COMPENSATION     SECURITIES
                                                                               ----------------------   UNDERLYING
NAME AND PRINCIPAL POSITION                                           YEAR     SALARY($)    BONUS($)    OPTIONS(#)
- ------------------------------------------------------------------  ---------  ----------  ----------  -------------
<S>                                                                 <C>        <C>         <C>         <C>
Thomas H. Sinton .................................................       1998  $  181,250  $  120,000       52,500
 President and Chief Executive Officer                                   1997     150,000      --           --
Jeffrey M. Bizzack ...............................................       1998     150,000     115,000       30,000
 Senior Vice President, Sales                                            1997     131,250      82,000       --
Leslie A. Johnson ................................................       1998     150,000      90,000       30,000
 Senior Vice President, Client Services and Chief Service Officer        1997     131,250      30,000       19,500
Robert E. Schneider ..............................................       1998     150,000      75,000       15,000
 Senior Vice President, Product Development and Chief Technical          1997      82,980      25,000       --
 Officer
Steven E. Klei ...................................................       1998     150,000      50,000       30,000
 Senior Vice President, Finance and Chief Financial Officer              1997     127,100      30,000       --
</TABLE>
 
                                       39
<PAGE>
    The following table sets forth information regarding stock options granted
during the fiscal year ended June 30, 1998 to each of the Named Executive
Officers.
 
                          OPTION GRANTS IN FISCAL 1998
 
<TABLE>
<CAPTION>
                                                  INDIVIDUAL GRANTS(1)                         POTENTIAL REALIZABLE
                            ----------------------------------------------------------------     VALUE AT ASSUMED
                              NUMBER OF                                                       ANNUAL RATES OF STOCK
                             SECURITIES     PERCENT OF TOTAL     EXERCISE                     PRICE APPRECIATION FOR
                             UNDERLYING    OPTIONS GRANTED TO    PRICE PER                      OPTION TERM ($)(4)
                               OPTIONS     EMPLOYEES IN FISCAL     SHARE                      ----------------------
NAME                        GRANTED(#)(1)      1998 (%)(2)        ($)(3)     EXPIRATION DATE      5%         10%
- --------------------------  -------------  -------------------  -----------  ---------------  ----------  ----------
<S>                         <C>            <C>                  <C>          <C>              <C>         <C>
Thomas H. Sinton..........       52,500              5.78            13.08       11/17/2007    1,902,075   3,321,675
Jeffrey M. Bizzack........       30,000              3.30             5.83        8/12/2007    1,282,800   2,051,100
Leslie A. Johnson.........       30,000              3.30             5.83        8/12/2007    1,282,800   2,051,100
Robert E. Schneider.......       15,000              1.65             5.83        8/12/2007      641,400   1,025,550
Steven E. Klei............       30,000              3.30             5.83        8/12/2007    1,282,800   2,051,100
</TABLE>
 
- ------------------------
 
(1) The options granted are immediately exercisable, but are subject to
    repurchase in the event the optionee's employment with the Company ceases
    for any reason. The options generally vest over four years as follows: 25%
    of the shares one year from the grant date and as to 1/48th of the shares in
    each successive month thereafter, with full vesting occurring on the fourth
    anniversary date. The options have a term of ten years, subject to earlier
    termination in certain situations related to termination of employment. See
    "Stock Plans."
 
(2) Based on a total of 907,875 options granted to all employees, consultants
    and directors during fiscal 1998.
 
(3) Represents the fair market value of the underlying Common Stock as
    determined by the Board of Directors on the date of grant.
 
(4) The potential realizable value at 5% and 10% appreciation is calculated by
    assuming that the last reported sales price of $31.17 per share on June 30,
    1998 appreciates at the indicated rate for the remaining portion of the term
    of the option and that the option is exercised at the exercise price and
    sold on the last day of its term at the appreciated price. Stock price
    appreciation of 5% and 10% is assumed pursuant to rules promulgated by the
    Securities and Exchange Commission and does not represent the Company's
    prediction of its stock price performance.
 
                                       40
<PAGE>
    The following table sets forth for each of the Named Executive Officers the
shares acquired and the value realized on each exercise of stock options during
the year ended June 30, 1998 and the number and value of securities underlying
unexercised options held by the Named Executive Officers at June 30, 1998.
 
                    FISCAL YEAR AGGREGATED OPTION EXERCISES
                       AND FISCAL YEAR-END OPTION VALUES
 
<TABLE>
<CAPTION>
                                                                       NUMBER OF SECURITIES
                                                                      UNDERLYING UNEXERCISED       VALUE OF UNEXERCISED
                                                                     OPTIONS AT FISCAL YEAR-     IN-THE- MONEY OPTIONS AT
                                                                              END(#)              FISCAL YEAR-END($)(1)
                                  SHARES ACQUIRED       VALUE       --------------------------  --------------------------
NAME                              ON EXERCISE(#)     REALIZED($)    EXERCISABLE  UNEXERCISABLE  EXERCISABLE  UNEXERCISABLE
- --------------------------------  ---------------  ---------------  -----------  -------------  -----------  -------------
<S>                               <C>              <C>              <C>          <C>            <C>          <C>
Thomas H. Sinton................        --               --             --            52,500        --            949,377
Jeffrey M. Bizzack..............        --               --             --            30,000        --            760,001
Leslie A. Johnson...............        --               --              8,531        40,969       238,868      1,067,133
Robert E. Schneider.............        --               --             --            15,000        --            380,001
Steven E. Klei..................        --               --             18,250        46,250       563,986      1,262,181
</TABLE>
 
- ------------------------
 
(1) The amount set forth represents the difference between the closing Common
    Stock share price of $31.17 on June 30, 1998, as reported by the Nasdaq
    National Market, and the applicable exercise price, multiplied by the
    applicable number of options.
 
STOCK PLANS
 
    1989 STOCK OPTION PLAN.  The Company's 1989 Stock Option Plan (the "1989
Plan") provided for the granting to employees (including officers and employee
directors) of "incentive stock options" within the meaning of the Internal
Revenue Code of 1986, as amended (the "Code") and for the granting to employees,
directors and consultants of nonstatutory stock options. In February 1997, the
Board of Directors of the Company increased the shares available for future
grants under the 1989 Plan by 2,063,649 for a total of 4,480,872. Options
granted under the 1989 Plan before the effective date of the amendment and
restatement to the 1996 Plan in September, 1997, described below, remain
outstanding in accordance with their terms, but no further options were granted
under the 1989 Plan after the effective date of the amendment and restatement to
the 1996 Plan.
 
    1996 STOCK OPTION PLAN.  The Company's 1996 Stock Option Plan (the "1996
Plan") was adopted by the Board of Directors in February 1996 under the name
"Executive Stock Option Plan." The 1996 Plan provides for the granting to
employees (including officers and employee directors) of incentive stock options
and for the granting to employees, directors and consultants of nonstatutory
stock options. In November 1996 and February 1997, the Board of Directors of the
Company approved, effective September 19, 1997, an amendment and restatement of
the 1996 Plan to (i) rename the Executive Stock Option Plan as the "1996 Stock
Option Plan" and (ii) authorize an increase in the number of shares reserved for
issuance under the plan of any unused or canceled shares under the 1989 Plan
plus annual increases equal to the lesser of (a) 375,000 shares, (b) two percent
(2%) of the number of outstanding shares of Common Stock on such date or (c) a
lesser amount determined by the Board. The 1996 Plan is administered by the
Board of Directors or a committee appointed by the Board (the "Administrator")
and has a term of ten years. As of June 30, 1998, the Company had granted an
aggregate of 4,894,788 shares of Common Stock under the 1996 Plan and the 1989
Plan. As of June 30, 1998, options to purchase an aggregate of 1,800,416 shares
of Common Stock were outstanding under the 1996 Plan and the 1989 Plan and
1,277,510 shares remained available for future grants under the 1996 Plan.
 
    Subject to the provisions of the 1996 Plan, the Administrator has the
authority to determine the individuals to whom stock options are to be granted,
the number of shares to be covered by each option, the exercise price, the fair
market value of the Common Stock, the type of option, the term of the option,
 
                                       41
<PAGE>
the restrictions, if any, on the exercise of the option, the terms for the
payment of the option price and other terms and conditions. Incentive stock
options granted under the 1996 Plan must have an exercise price of (i) at least
110% of fair market value of the Common Stock on the date of grant if granted to
an employee who owns stock representing more than 10% of the voting power of all
classes of stock of the Company, any parent or any subsidiary or (ii) at least
100% of fair market value of the Common Stock on the date of grant if granted to
any other employee. In the case of a nonstatutory stock option, the per share
exercise price is determined by the Administrator. No participant may be granted
in any fiscal year of the Company an option to purchase more than 187,500
shares, and over the remaining term of the 1996 Plan such participant may not be
granted options to purchase more than 375,000 additional shares. Payments by
option holders upon exercise of an option may be made (as determined by the
Administrator) in cash or such other form of payment as permitted under the 1996
Plan, including without limitation, by promissory note or by surrender of
certain shares of Common Stock. In addition, an optionee may pay the exercise
price by means of a so-called "cashless exercise." In the event of a proposed
merger of the Company with or into another corporation, outstanding options may
be assumed or equivalent options may be substituted by such successor
corporation or a parent or subsidiary of such successor corporation. In the
event that such successor corporation does not agree to assume options or
substitute equivalent options, optionees will have the right to exercise their
options as to all shares subject to such options, including shares as to which
options would not otherwise be exercisable.
 
    1997 EMPLOYEE STOCK PURCHASE PLAN.  The Company's 1997 Employee Stock
Purchase Plan (the "Purchase Plan") was adopted by the Board of Directors in
November 1996 and amended in August 1997 and September 1997. The Company has
reserved a total of 750,000 shares of Common Stock for issuance under the
Purchase Plan, of which 170,114 have been issued, with the number of shares to
be increased annually on each anniversary date of the adoption of the Purchase
Plan by a number of shares equal to the lesser of (i) 225,000 shares, (ii) one
and one-half percent (1.5%) of the outstanding number of shares on such date or
(iii) a lesser number determined by the Board. The Purchase Plan, which is
intended to qualify under Section 423 of the Code, permits eligible employees of
the Company to purchase Common Stock through payroll deductions of up to 10% of
their base straight time gross earnings and commissions, including payments for
overtime, shift premiums, incentive compensation, incentive payments, bonuses or
other payments. An eligible employee's right to purchase stock under the
Purchase Plan may not accrue at a rate that exceeds $25,000 worth of stock in
any calendar year. The price of Common Stock purchased under the Purchase Plan
will be 85% of the lower of the fair market value of the Common Stock on the
first day of an offering period or last day of the applicable purchase period.
Employees may end their participation in the Purchase Plan at any time during an
offering period, and they will be paid their payroll deductions to date.
Participation ends automatically upon termination of employment with the
Company. Rights granted under the Purchase Plan are not transferable by a
participant other than by will, the laws of descent and distribution, or as
otherwise provided under the plan. The initial offering period under the
Purchase Plan is approximately 26 months and commenced on September 19, 1997 and
will end on the last trading day on or before November 15, 1999. A second
offering period commenced on May 18, 1998 and will end on the last trading day
on or before May 15, 2000. Subsequent offering periods will last 24 months and
will commence on the first trading day on or after November 16 and May 16 of
each year during which the Purchase Plan is in effect, and will terminate on the
last trading day in the periods ending 24 months later. Each 24-month offering
period will consist of four purchase periods of approximately six months
duration. The Purchase Plan will be administered by the Board of Directors or by
a committee appointed by the Board. Employees are eligible to participate if
they are customarily employed by the Company or any designated subsidiary for at
least 20 hours per week and for more than five months in any calendar year.
 
401(K) PLAN
 
    The Company maintains a 401(k) retirement savings plan (the "401(k) Plan").
The 401(k) Plan provides that each participant may contribute up to 18% of his
or her pre-tax gross compensation (up to a
 
                                       42
<PAGE>
statutorily prescribed annual limit of $10,000 in 1998). The percentage elected
by certain highly compensated participants may be required to be lower. All
amounts contributed by employee participants and earnings on these contributions
are fully vested at all times. Employee participants may elect to invest their
contributions in various established funds.
 
LIMITATION OF LIABILITY AND INDEMNIFICATION MATTERS
 
    The Company's Amended and Restated Certificate of Incorporation limits the
liability of directors to the maximum extent permitted by Delaware law. Delaware
law provides that a corporation's certificate of incorporation may contain a
provision eliminating or limiting the personal liability of directors for
monetary damages for breach of their fiduciary duties as directors, except for
liability (i) for any breach of their duty of loyalty to the corporation or its
stockholders, (ii) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) for unlawful
payments of dividends or unlawful stock repurchases or redemptions as provided
in Section 174 of the Delaware General Corporation Law or (iv) for any
transaction from which a director derives an improper personal benefit.
 
    The Company's Bylaws provide that the Company shall indemnify its directors
and officers and may indemnify its employees and agents to the fullest extent
permitted by law.
 
    The Company has entered into agreements to indemnify its directors and
officers, in addition to the indemnification provided for in the Company's
Amended and Restated Certificate of Incorporation and Bylaws. These agreements,
among other things, indemnify the Company's directors and officers for certain
expenses (including attorneys' fees), judgments, fines and settlement amounts
incurred by any such person in any action or proceeding, including any action by
or in the right of the Company, arising out of such person's services as a
director or officer of the Company, any subsidiary of the Company or any other
company or enterprise to which the person provides services at the request of
the Company. The Company believes that these provisions and agreements are
necessary to attract and retain qualified directors and officers.
 
    At present, there is no pending litigation or proceeding involving any
director, officer, employee or agent of the Company where indemnification will
be required or permitted. The Company is not aware of any threatened litigation
or proceeding that might result in a claim for such indemnification.
 
COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION
 
    The Compensation Committee is composed of Messrs. Hodgson and Readmond. No
interlocking relationship exists between any member of the Company's Board of
Directors and the board of directors or compensation committee of any other
company, nor has any such interlocking relationship existed in the past.
 
                                       43
<PAGE>
                              CERTAIN TRANSACTIONS
 
    Between May 1994 and September 1995, Thomas H. Sinton, a Director and
officer of the Company, and his immediate family loaned an aggregate of
$1,040,000 to the Company at interest rates of 10.0% per year. The Company has
paid all such loans in full.
 
    On December 5, 1996, the Company loaned $544,000 under a full recourse note
agreement at an interest rate of 6.31% per year to Robert E. Schneider, an
officer of the Company, to permit Mr. Schneider to exercise options to purchase
Common Stock of the Company. All principal and interest is due December 5, 2000.
As of June 30, 1998, Mr. Schneider had not paid any amount on the note.
 
    On January 31, 1997, the Company loaned $250,000 under a full recourse note
agreement at an interest rate of 6.1% per year to Jeffrey M. Bizzack, an officer
of the Company, to permit Mr. Bizzack to purchase a residence. Accrued interest
must be paid on a monthly basis beginning two years from the date of the note.
All principal and accrued but unpaid interest is due January 31, 2001 unless Mr.
Bizzack's employment with the Company terminates, in which case, the note may
become due earlier. As of June 30, 1998, Mr. Bizzack had not paid any amount on
the note.
 
    It is anticipated that Lafayette Investments, Inc., an affiliate of the
Company, will be an Underwriter in the Offering and will receive a portion of
the underwriting discount. Thomas P. Roddy, a Director of the Company, is
President and Chief Executive Officer of Lafayette Investments, Inc. See
"Underwriting."
 
    Thomas H. Sinton and certain affiliates of GAP LLC are the sole stockholders
of InterPro Expense Systems, Inc., a Delaware corporation ("InterPro"), which in
April 1998 purchased rights to certain early-stage travel and entertainment
expense processing software. Mr. Sinton is the President, Chief Executive
Officer and Chairman of the Board of the Company. David C. Hodgson, a Director
of the Company, is a managing member of GAP LLC, affiliates of which hold more
than 5% of the Company's outstanding stock. Because Mr. Sinton and Mr. Hodgson
are officers and Directors of the Company, their investment in InterPro was
required to be, and was, approved by the disinterested directors of the Company.
Any future transaction or relationship between the Company and InterPro would be
entered into on an arms-length basis and would be approved by the Company's
disinterested directors.
 
    Information with respect to compensation to directors and executive officers
is set forth under "Management -- Director Compensation" and "-- Executive
Compensation."
 
                                       44
<PAGE>
                             PRINCIPAL STOCKHOLDERS
 
    The following table sets forth certain information regarding the beneficial
ownership of Common Stock, as of June 30, 1998, concerning (a) each person or
entity known by the Company to own beneficially more than 5% of the outstanding
shares of Common Stock, (b) each director of the Company, (c) each of the Named
Executive Officers, and (d) all directors and executive officers of the Company
as a group. Unless otherwise noted in the footnotes to the table, (i) the
Company believes that the persons named in the table have sole voting and
investment power with respect to all shares of Common Stock indicated as being
beneficially owned by them and (ii) officers and directors can be contacted at
the principal offices of the Company.
 
<TABLE>
<CAPTION>
                                                                                                  PERCENTAGE OF SHARES
                                                                                                 BENEFICIALLY OWNED(1)
                                                                                     SHARES     ------------------------
                                                                                   BENEFICIALLY  PRIOR TO       AFTER
NAME OF BENEFICIAL OWNERS                                                             OWNED      OFFERING     OFFERING
- ---------------------------------------------------------------------------------  -----------  -----------  -----------
<S>                                                                                <C>          <C>          <C>
Thomas H. Sinton(2)..............................................................   4,190,246         24.5%        21.4%
General Atlantic Partners, LLC(3)................................................   2,174,199         12.7         11.1
Jeffrey M. Bizzack(4)............................................................     180,061        *            *
Leslie A. Johnson(5).............................................................     134,361        *            *
Steven E. Klei(6)................................................................      84,173        *            *
William T. Clifford(7)...........................................................       5,625        *            *
David C. Hodgson(3)..............................................................   2,179,824         12.7         11.1
Ronald W. Readmond(8)............................................................      17,881        *            *
Thomas P. Roddy(9)...............................................................     314,731          1.8          1.6
Robert E. Schneider(10)..........................................................     118,081        *            *
All executive officers and directors as a group (9 persons)(11)..................   7,224,983         42.0         36.7
</TABLE>
 
- ------------------------
 
 *  Represents beneficial ownership of less than one percent.
 
(1) Based on 17,114,855 shares of Common Stock outstanding prior to the Offering
    and 19,589,855 outstanding upon completion of the Offering. A person is
    deemed to be the beneficial owner of securities that can be acquired by such
    person within 60 days of June 30, 1998 upon the exercise of warrants or
    vested options. Calculations of percentage of beneficial ownership assume
    the exercise by only the respective named stockholder of all options and
    warrants for the purchase of Common Stock held by such stockholder which are
    exercisable within 60 days of June 30, 1998.
 
(2) Includes 14,219 shares issuable upon exercise of vested options and 46,875
    shares subject to the Company's repurchase rights. Also includes shares held
    by the Silas D. Trust Estate, the Silas Jack Sinton Family Trust, the Thomas
    H. Sinton and Jane Nibley Sinton 1989 Irrevocable Trust and Jane N. Sinton
    as a custodian for minor children.
 
(3) Includes 1,851,009 shares held by General Atlantic Partners 39, L.P. ("GAP
    39") and 323,190 shares held by GAP Coinvestment Partners, L.P. ("GAP
    Coinvestment"). The general partner of GAP 39 is GAP LLC. The managing
    members of GAP LLC are Steven A. Denning, Stephen P. Reynolds, David C.
    Hodgson, J. Michael Cline, William O. Grabe and William E. Ford. The same
    managing members of GAP LLC are the general partners of GAP Coinvestment.
    Mr. Hodgson is a director of the Company. Mr. Hodgson disclaims beneficial
    ownership of shares owned by GAP 39 and GAP Coinvestment, except to the
    extent of his pecuniary interests therein. Also includes with respect to Mr.
    Hodgson 5,625 shares issuable upon exercise of vested options held
    personally by Mr. Hodgson. The address for GAP 39, GAP Coinvestment, GAP LLC
    and Mr. Hodgson is c/o General Atlantic Service Corporation, Three Pickwick
    Plaza, Greenwich, CT 06830.
 
                                       45
<PAGE>
(4) Includes 7,500 shares issuable upon exercise of vested options and 17,031
    shares subject to the Company's repurchase rights.
 
(5) Includes 16,844 shares issuable upon exercise of vested options and 6,249
    shares subject to the Company's repurchase rights. Also includes 15,894
    shares held by Weir L. Johnson, of which 6,843 shares are issuable upon
    exercise of vested options and 3,281 shares are subject to the Company's
    repurchase rights.
 
(6) Includes 28,250 shares issuable upon exercise of vested options and 16,406
    shares subject to the Company's repurchase rights.
 
(7) Represents 5,625 shares issuable upon exercise of vested options held by Mr.
    Clifford.
 
(8) Includes 8,437 shares issuable upon exercise of vested options held by Mr.
    Readmond.
 
(9) Includes (i) 39,345 shares held by the Lafayette Investments Inc. of which
    Mr. Roddy is President and Chief Executive Officer, (ii) 27,600 shares held
    by the Lafayette Investments Inc. 401(k) Plan and Trust, (iii) 51,207 shares
    held by Delaware Charter Guarantee FBO Thomas P. Roddy R-IRA, (iv) 24,000
    shares held by Guarantee and Trust Co. TTEE FBO Thomas P. Roddy IRA and (v)
    13,302 by Mary W. Roddy.
 
(10) Includes 3,750 shares issuable upon exercise of vested options and 65,625
    shares subject to the Company's repurchase rights.
 
(11) Includes 97,093 shares issuable upon exercise of vested options and 155,737
    shares subject to the Company's repurchase rights.
 
                                       46
<PAGE>
                          DESCRIPTION OF CAPITAL STOCK
 
    The authorized capital stock of the Company consists of 60,000,000 shares of
Common Stock, par value $0.001 per share ("Common Stock"), and 5,000,000 shares
of Preferred Stock, par value $0.001 per share ("Preferred Stock"). The
following summary is qualified in its entirety by reference of the Company's
Certificate of Incorporation, which is filed as an exhibit to the Registration
of which this Prospectus is a part.
 
COMMON STOCK
 
    As of June 30, 1998, there were 17,114,855 shares of Common Stock
outstanding held of record by 376 stockholders. The holders of Common Stock are
entitled to one vote for each share held of record on all matters submitted to a
vote of the stockholders. The holders of Common Stock are not entitled to
cumulative voting rights with respect to the election of directors, and as a
consequence, minority stockholders will not be able to elect directors on the
basis of their votes alone. Subject to preferences that may be applicable to any
then outstanding shares of Preferred Stock, holders of Common Stock are entitled
to receive ratably such dividends as may be declared by the Board of Directors
out of funds legally available therefore. See "Dividend Policy." In the event of
a liquidation, dissolution or winding up of the Company, holders of Common Stock
are entitled to share ratably in all assets remaining after payment of
liabilities and the liquidation preference of any then outstanding Preferred
Stock. Holders of Common Stock have no preemptive rights and no right to convert
their Common Stock into any other securities. There are no redemption or sinking
fund provisions applicable to the Common Stock. All outstanding shares of Common
Stock are, and all shares of Common Stock to be outstanding upon completion of
this Offering will be, fully paid and nonassessable.
 
PREFERRED STOCK
 
    The Board of Directors have the authority, without further action by the
stockholders, to issue up to 5,000,000 shares of Preferred Stock in one or more
series and to fix the rights, preferences, privileges and restrictions thereof,
including dividend rights, conversion rights, voting rights, terms of
redemption, liquidation preferences, sinking fund terms and the number of shares
constituting any series or the designation of such series, without any further
vote or action by stockholders. The issuance of Preferred Stock could adversely
affect the voting power of holders of Common Stock and the likelihood that such
holders will receive dividend payments and payments upon liquidation and could
have the effect of delaying, deferring or preventing a change in control of the
Company. The Company has no present plan to issue any shares of Preferred Stock.
 
WARRANTS
 
    In connection with a loan agreement, the Company issued Coast Business
Credit ("Coast") a warrant to purchase 28,500 shares of the Company's Common
Stock at an exercise price of $2.65 per share, exercisable at any time through
April 30, 2001. In connection with an amendment to the loan agreement between
Coast and the Company to extend the line of credit, the Company issued a warrant
to Coast to purchase an additional 28,500 shares of the Company's Common Stock
at an exercise price of $2.65 per share, exercisable through October 25, 2001.
In connection with a built-to-suit lease, the Company issued Britannia Hacienda
V Limited Partnership ("Britannia Hacienda") and its partners warrants to
purchase an aggregate of 67,500 shares of Common Stock at an exercise price of
$2.65 per share, exercisable through September 24, 2002. In connection with its
acquisition of BeneSphere, the Company issued warrants to purchase an aggregate
of 75,000 shares of Common Stock to two former shareholders of BeneSphere at an
exercise price of $6.00 per share, exercisable at any time through January 7,
2002. On July 1, 1997, the Company issued a warrant to purchase an aggregate of
30,000 shares of Common Stock at a purchase price of $6.00 per share exercisable
through July 1, 2002.
 
                                       47
<PAGE>
REGISTRATION RIGHTS OF CERTAIN HOLDERS
 
    The holders (or their permitted transferees) of approximately 9,571,976
shares of Common Stock and 124,500 shares issuable upon exercise of warrants
(collectively the "Holders") are entitled to certain rights with respect to the
registration of such shares under the Securities Act of 1933, as amended (the
"Securities Act"). If the Company proposes to register its Common Stock, subject
to certain exceptions, under the Securities Act, the Holders are entitled to
notice of the registration and are entitled to include, at the Company's
expense, such shares therein, provided that the managing underwriter has the
right to limit a certain number of such shares included in the registration. The
Holders have waived their registration right with respect to this Offering. In
addition, certain of the Holders may require the Company at its expense on no
more than two occasions to file a registration statement under the Securities
Act with respect to their shares of Common Stock. Such rights may not be
exercised until 180 days after the completion of this Offering. In addition, GAP
LLC may request the Company to file a registration statement under the
Securities Act with respect to 1,724,199 shares of Common Stock on one occasion
as long as certain conditions are met. If the Holders, by exercising their
demand registration rights, cause a large number of securities to be registered
and sold in the public market, such sales could have an adverse effect on the
market price for the Company's Common Stock. Moreover, if the Company were to
include in a Company initiated registration shares held by the Holders pursuant
to exercise of their "piggyback" registration rights, such sales may have an
adverse effect on the Company's ability to raise additional capital.
 
DELAWARE LAW AND CERTAIN CHARTER AND BYLAW PROVISIONS
 
    The Company is subject to the provisions of Section 203 of the General
Corporation Law of Delaware. Section 203 prohibits a publicly-held Delaware
corporation from engaging in a "business combination" with an "interested
stockholder" for a period of three years after the date of the transaction in
which the person became an interested stockholder, unless the business
combination is approved in a prescribed manner. A "business combination"
includes mergers, asset sales and other transactions resulting in a financial
benefit to the interested stockholder. Subject to certain exceptions, an
"interested stockholder" is a person who, together with affiliates and
associates, owns, or within three years did own, 15% or more of the
corporation's voting stock.
 
    The Company's Amended and Restated Certificate of Incorporation (the
"Charter") provides for the division of the Board of Directors into three
classes with staggered three-year terms. See "Management -- Executive Officers
and Directors." Under the Charter, any vacancy on the Board of Directors,
however occurring, including a vacancy resulting from an enlargement of the
Board, may only be filled by vote of a majority of the directors then in office.
The classification of the Board of Directors and the limitations on the removal
of directors and filling of vacancies could have the effect of making it more
difficult for a third party to acquire, or of discouraging a third party from
acquiring, control of the Company.
 
    The Charter also provides that any action required or permitted to be taken
by the stockholders of the Company at an annual meeting or special meeting of
stockholders may only be taken if it is properly brought before such meeting and
may not be taken by written action in lieu of a meeting. The Charter further
provides that special meetings of the stockholders may only be called by the
Chairman of the Board of Directors, the Chief Executive Officer, the President
of the Company, the Board of Directors or the holders of shares entitled to cast
not less than 40% of the votes at that meeting. Under the Bylaws, in order for
any matter to be considered "properly brought" before a meeting, a stockholder
must comply with certain requirements regarding advance notice to the Company.
The foregoing provisions could have the effect of delaying until the next
stockholders meeting stockholder actions which are favored by the holders of a
majority of the outstanding voting securities of the Company. These provisions
may also discourage another person or entity from making a tender offer for the
Company's Common Stock, because such person or entity, even if it acquired a
majority of the outstanding voting securities of the Company, would
 
                                       48
<PAGE>
be able to take action as a stockholder (such as electing new directors or
approving a merger) only at a duly called stockholders meeting, and not by
written consent.
 
    The General Corporation Law of Delaware provides generally that the
affirmative vote of a majority of the shares entitled to vote on any matter is
required to amend a corporation's certificate of incorporation or bylaws, unless
a corporation's certificate of incorporation or bylaws, as the case may be,
requires a greater percentage. The Charter requires the affirmative vote of the
holders of at least 66 2/3% of the shares of capital stock of the Company issued
and outstanding and entitled to vote to amend or repeal any of the foregoing
Charter provisions. The 66 2/3% stockholder vote would be in addition to any
separate class vote that might in the future be required pursuant to the terms
of any series Preferred Stock that might be outstanding at the time any such
amendments are submitted to stockholders. The Bylaws also may be amended or
repealed by a majority vote of the Board of Directors subject to any limitations
set forth in the Bylaws.
 
TRANSFER AGENT AND REGISTRAR
 
    Norwest Bank Minnesota, National Association is the transfer agent and
registrar for the Company's Common Stock.
 
                                       49
<PAGE>
                        SHARES ELIGIBLE FOR FUTURE SALE
 
    Sales of substantial numbers of shares of Common Stock in the public market
following this Offering, or the perception that such sales could occur, could
adversely affect the market price for the Common Stock. Furthermore, sales of
substantial amounts of Common Stock in the public market after various resale
restrictions lapse could adversely affect the prevailing market price and the
ability of the Company to raise equity capital in the future.
 
    Upon completion of this Offering, the Company will have outstanding an
aggregate of 19,589,855 shares of Common Stock, based upon the number of shares
outstanding as of June 30, 1998. Of these shares, all of the shares sold in this
Offering and the 4,312,500 shares sold in the Company's initial public offering
will be freely tradeable without restriction or further registration under the
Securities Act. There are currently outstanding 2,539,100 shares of Common Stock
issued pursuant to exercise of options granted under equity incentive plans of
the Company, all of which shares are freely tradeable pursuant to Rule 701 of
the Securities Act or registration on a previously filed Form S-8. The remaining
10,263,255 shares of Common Stock were issued and sold by the Company in private
transactions exempt from registration requirements of the Securities Act and
will be available for immediate sale in the public market in accordance with
Rule 144, in some cases subject to transfer restrictions in lock-up agreements
with William Blair & Company, L.L.C. described below and the volume and other
resale limitations of Rule 144, other than the one year holding period. In
addition, as of June 30, 1998, there were outstanding options to purchase
1,800,416 shares of Common Stock and warrants to purchase 229,500 shares of
Common Stock.
 
    The Company and its directors, executive officers and certain stockholders
(together, holding an aggregate of 7,127,890 shares of the Company's Common
Stock) have agreed not to offer, sell, contract to sell or otherwise dispose of
any shares of Common Stock or any securities convertible into shares of Common
Stock or register for sale under the Securities Act any shares of Common Stock
for a period of 90 days after the date of this Prospectus without the prior
written consent of William Blair & Company, L.L.C., other than the Company's
sale of shares in this Offering, the issuance of Common Stock upon the exercise
of outstanding options, and the Company's issuance of options and shares under
existing stock option and stock purchase plans.
 
    The holders of approximately 9,571,976 shares of Common Stock and 124,500
shares of Common Stock issuable upon exercise of warrants are parties to
registration rights agreements with the Company that provide "piggyback"
registration rights that allow such holders, under certain circumstances, to
include shares of Common Stock in registration statements initiated by the
Company or other stockholders. Such registration rights agreements also permit
demand registrations on Form S-3 registration statements, provided the Company
is eligible to register securities on such form. The number of shares sold in
the public market could increase if any holders exercise such rights. See
"Description of Capital Stock -- Registration Rights."
 
    In general, under Rule 144 as currently in effect, an affiliate of the
Company, or person (or persons whose shares are aggregated) who has beneficially
owned, for at least one year but less than two years, securities subject to Rule
144, is entitled to sell in any three month period a number of shares that does
not exceed the greater of (i) 1% of the then-outstanding shares of the Common
Stock (approximately 195,898 shares immediately after the Offering) or (ii) the
average weekly trading volume during the four calendar weeks immediately
preceding the date on which notice of the sale is filed with the Securities and
Exchange Commission. Sales pursuant to Rule 144 are subject to certain
requirements relating to manner of sale, notice and availability of current
public information about the Company. A person (or persons whose shares are
aggregated) who is not deemed to have been an affiliate of the Company at any
time during the 90 days immediately preceding the sale and who has beneficially
owned the shares proposed to be sold for at least two years (including the
holding period of any prior owner except an affiliate) is entitled to sell such
shares pursuant to Rule 144(k) without complying with the requirements relating
to manner of sale,
 
                                       50
<PAGE>
notice and information availability described above. In general, under Rule 701
of the Securities Act as currently in effect, any employee, consultant or
advisor of the Company who purchases shares from the Company in connection with
a compensatory stock or option plan or other written agreement related to
compensation is eligible to resell such shares 90 days after the effective date
of the Company's initial public offering (which was completed September 19,
1997) in reliance on Rule 144, but without compliance with certain restrictions,
including the holding period, contained in Rule 144.
 
    No predictions can be made as to the effect, if any, that market sales of
shares of Common Stock prevailing from time to time may have on the market price
of the Common Stock. Nevertheless, sales of significant numbers of shares of the
Common Stock in the public market may adversely affect the market price of the
Common Stock offered hereby and could impair the Company's future ability to
raise capital through an offering of its equity securities.
 
                                       51
<PAGE>
                                  UNDERWRITING
 
    The several Underwriters named below (the "Underwriters"), for which William
Blair & Company, L.L.C., BancAmerica Robertson Stephens and SG Cowen Securities
Corporation are acting as representatives (the "Representatives"), have
severally agreed, subject to the terms and conditions set forth in the
Underwriting Agreement by and among the Company and the Underwriters (the
"Underwriting Agreement"), to purchase from the Company, and the Company has
agreed to sell to each of the Underwriters, the respective number of shares of
Common Stock set forth opposite each Underwriter's name in the table below:
 
<TABLE>
<CAPTION>
                                                                                   NUMBER OF
UNDERWRITER                                                                          SHARES
- ---------------------------------------------------------------------------------  ----------
<S>                                                                                <C>
William Blair & Company, L.L.C...................................................
BancAmerica Robertson Stephens...................................................
SG Cowen Securities Corporation..................................................
                                                                                   ----------
      Total......................................................................   2,475,000
                                                                                   ----------
                                                                                   ----------
</TABLE>
 
    The nature of the Underwriters' obligations under the Underwriting Agreement
is such that all shares of Common Stock offered hereby, excluding shares covered
by the over-allotment option granted to the Underwriters, must be purchased if
any are purchased.
 
    The Representatives have advised the Company that the Underwriters propose
to offer the shares of Common Stock to the public at the public offering price
set forth on the cover page of this Prospectus and to select dealers at such
price less a concession of not more than $      per share. The Underwriters may
allow, and such dealers may reallow, a concession not in excess of $      per
share to certain other dealers. After the public offering contemplated hereby,
the public offering price and other selling terms may be changed by the
Representatives.
 
    The Company has granted to the Underwriters an option exercisable within 30
days after the date of this Prospectus, to purchase up to an additional 371,250
shares of Common Stock to cover over-allotments, at the same price per share to
be paid by the Underwriters for the other shares offered hereby. If the
Underwriters purchase any such additional shares pursuant to this option, each
of the Underwriters will be committed to purchase such additional shares in
approximately the same proportion as set forth in the table above. The
Underwriters may exercise the option only for the purpose of covering
over-allotments, if any, made in connection with the distribution of the shares
of Common Stock offered hereby.
 
    The Company, its directors and executive officers and certain stockholders
of the Company have agreed not to offer, sell, contract to sell or otherwise
dispose of any shares of Common Stock or any securities convertible into shares
of Common Stock or register for sale under the Securities Act any shares of
Common Stock for a period of 90 days after the date of this Prospectus without
the prior written consent of William Blair & Company, L.L.C., other than the
Company's sale of shares in this Offering, the issuance of Common Stock upon the
exercise of outstanding options, and the Company's issuance of options and
shares under existing stock option and stock purchase plans. See "Shares
Eligible for Future Sale."
 
    The Representatives have advised the Company that, pursuant to Regulation M
under the Securities Exchange Act of 1934, as amended (the "Exchange Act"),
certain persons participating in the Offering may engage in transactions that
may stabilize, maintain or otherwise affect the market price of the
 
                                       52
<PAGE>
Common Stock, including stabilizing bids, syndicate covering transactions or the
imposition of penalty bids. A "stabilizing bid" is a bid for, or the purchase
of, the Common Stock on behalf of the Underwriters for the purpose of fixing or
maintaining the price of the Common Stock. A "syndicate covering transaction" is
the bid for, or the purchase of, the Common Stock on behalf of the Underwriters
to reduce a short position incurred by the Underwriters in connection with the
Offering. A "penalty bid" is an arrangement permitting the managing underwriter
to reclaim the selling concession otherwise accruing to an Underwriter or
syndicate member in connection with the Offering if the Common Stock originally
sold by such Underwriter or syndicate member is purchased by the Underwriters in
a syndicate covering transaction and has therefore not been effectively placed
by such Underwriter or syndicate member. The Representatives have advised the
Company that such transactions may be effected on the Nasdaq National Market or
otherwise and, if commenced, may be discontinued at any time.
 
    One or more of the Underwriters currently act as market makers for the
Common Stock and may engage in "passive market making" in such securities on the
Nasdaq National Market in accordance with Rule 103 of Regulation M under the
Exchange Act. Rule 103 permits, upon the satisfaction of certain conditions,
underwriters participating in a distribution that are also Nasdaq market makers
in the security being distributed to engage in limited market making
transactions during the period when Rule 103 would otherwise prohibit such
activity. Rule 103 prohibits underwriters engaged in passive market making
generally from entering a bid or effecting a purchase price that exceeds the
highest bid for those securities displayed on the Nasdaq National Market by a
market maker that is not participating in the distribution. Under Rule 103, each
underwriter engaged in passive market making is subject to a daily net purchase
limitation equal to the greater of (i) 30% of such entity's average daily
trading volume during the two full calendar months immediately preceding, or any
60 consecutive calendar days ending within the ten calendar days preceding, the
date of the filing of the registration statement under the Securities Act
pertaining to the security to be distributed or (ii) 200 shares of common stock.
 
    The Company has agreed to indemnify the Underwriters against certain
liabilities, including liabilities under the Securities Act, or to contribute to
payments the Underwriters may be required to make in respect thereof.
 
                                 LEGAL MATTERS
 
    The legality of the issuance of the shares of Common Stock offered hereby
will be passed upon for the Company by Wilson Sonsini Goodrich & Rosati,
Professional Corporation, Palo Alto, California. As of June 30, 1998, certain
members of Wilson Sonsini Goodrich & Rosati, P.C. beneficially owned an
aggregate of 12,268 shares of the Company's Common Stock. Certain legal matters
in connection with this Offering will be passed upon for the Underwriters by
Cooley Godward LLP, San Francisco, California.
 
                                    EXPERTS
 
    The financial statements of ProBusiness Services, Inc. as of June 30, 1997
and 1998 and for each of the three years in the period ended June 30, 1998
appearing in this Prospectus and elsewhere in the Registration Statement have
been audited by Ernst & Young LLP, independent auditors, as set forth in their
report thereon appearing elsewhere herein and in the Registration Statement, and
are included in reliance upon such report given upon the authority of such firm
as experts in accounting and auditing.
 
                             ADDITIONAL INFORMATION
 
    The Company has filed with the Securities and Exchange Commission (the
"Commission"), a Registration Statement on Form S-1 and exhibits and schedules
thereto under the Securities Act, with respect to the Common Stock offered
hereby. This Prospectus does not contain all of the information set forth in the
Registration Statement and the exhibits and schedules thereto. Certain items are
omitted in accordance with the rules and regulations of the Commission. For
further information with respect to the
 
                                       53
<PAGE>
Company and the Common Stock offered hereby, reference is made to the
Registration Statement and the exhibits and schedules filed therewith.
Statements contained in this Prospectus as to the contents of any contract or
any other document referred to are not necessarily complete, and, in each
instance, reference is made to the copy of such contract or document filed as an
exhibit to the Registration Statement, each such statement being qualified in
all respects by such reference to such exhibit. A copy of the Registration
Statement, and the exhibits and schedules thereto, may be inspected without
charge at the public reference facilities maintained by the Commission in Room
1024, 450 Fifth Street, N.W., Washington, D.C. 20549, and at the Commission's
regional offices located at the Northwestern Atrium Center, 500 West Madison
Street, Suite 1400, Chicago, Illinois 60661 and Seven World Trade Center, 13th
Floor, New York, New York 10048, and copies of all or any part of the
Registration Statement may be obtained from the Commission upon the payment of
the fees prescribed by the Commission.
 
    The Company is subject to the information requirements of the Exchange Act
and in accordance therewith files reports and other information with the
Commission. Reports, proxy statements and other information filed by the Company
can be inspected and copied (at prescribed rates) at the locations listed above.
Quotations relating to the Company's Common Stock appear on the Nasdaq National
Market and such reports, proxy statements and other information concerning the
Company also can be inspected at the offices of the Nasdaq Stock Market, 1753 K
Street, N.W., Washington, D.C. 20006. The Commission maintains a World Wide Web
site that contains reports, proxy and information statements and other
information regarding registrants that file electronically with the Commission.
The address of the site is http://www.sec.gov.
 
                                       54
<PAGE>
                           PROBUSINESS SERVICES, INC.
                         INDEX TO FINANCIAL STATEMENTS
 
<TABLE>
<CAPTION>
                                                                                                                PAGE
<S>                                                                                                          <C>
Report of Independent Auditors.............................................................................         F-2
Balance Sheets.............................................................................................         F-3
Statements of Operations...................................................................................         F-4
Statements of Stockholders' Equity (Deficit)...............................................................         F-5
Statements of Cash Flows...................................................................................         F-6
Notes to Financial Statements..............................................................................         F-8
</TABLE>
 
                                      F-1
<PAGE>
                         REPORT OF INDEPENDENT AUDITORS
 
The Board of Directors and Stockholders
ProBusiness Services, Inc.
 
We have audited the accompanying balance sheets of ProBusiness Services, Inc. as
of June 30, 1997 and 1998 and the related statements of operations,
stockholders' equity (deficit), and cash flows for each of the three years in
the period ended June 30, 1998. These financial statements are the
responsibility of the Company's management. Our responsibility is to express an
opinion on these financial statements based on our audits.
 
We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to obtain
reasonable assurance about whether the financial statements are free of material
misstatement. An audit includes examining, on a test basis, evidence supporting
the amounts and disclosures in the financial statements. An audit also includes
assessing the accounting principles used and significant estimates made by
management, as well as evaluating the overall financial statement presentation.
We believe that our audits provide a reasonable basis for our opinion.
 
In our opinion, the financial statements referred to above present fairly, in
all material respects, the financial position of ProBusiness Services, Inc. at
June 30, 1997 and 1998 and the results of its operations and its cash flows for
each of the three years in the period ended June 30, 1998 in conformity with
generally accepted accounting principles.
 
                                          /s/ ERNST & YOUNG LLP
 
Walnut Creek, California
July 23, 1998
 
                                      F-2
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                                 BALANCE SHEETS
 
               (IN THOUSANDS, EXCEPT SHARE AND PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                                                                                                   JUNE 30,
                                                                                            ----------------------
                                                                                               1997        1998
                                                                                            ----------  ----------
<S>                                                                                         <C>         <C>
                                                      ASSETS
 
Current assets:
  Cash and cash equivalents...............................................................  $    5,047  $   13,771
  Accounts receivable, net of allowance of $365,000 at June 30, 1997 and $420,000 at June
    30, 1998..............................................................................       2,476       2,612
  Prepaid expenses and other current assets...............................................         643       2,122
                                                                                            ----------  ----------
                                                                                                 8,166      18,505
Payroll tax funds invested................................................................     177,626     332,667
                                                                                            ----------  ----------
Total current assets......................................................................     185,792     351,172
Equipment, furniture and fixtures, net....................................................       7,623      13,958
Other assets..............................................................................       7,020      10,879
                                                                                            ----------  ----------
Total assets..............................................................................  $  200,435  $  376,009
                                                                                            ----------  ----------
                                                                                            ----------  ----------
 
                                 LIABILITIES AND STOCKHOLDERS' EQUITY
 
Current liabilities:
  Accounts payable........................................................................  $    1,089  $    1,750
  Accrued liabilities.....................................................................       4,984      10,403
  Deferred revenue........................................................................       1,279       2,139
  Current portion of capital lease obligations............................................         773         890
                                                                                            ----------  ----------
                                                                                                 8,125      15,182
Payroll tax funds collected but unremitted................................................     177,626     332,667
                                                                                            ----------  ----------
Total current liabilities.................................................................     185,751     347,849
Note payable to stockholder...............................................................         250      --
Long-term debt............................................................................       8,667      --
Capital lease obligations, less current portion...........................................       1,898       1,414
Commitments
Stockholders' equity:
  Preferred stock, $.001 par value; authorized: 5,000,000 shares; issued and outstanding:
    3,228,034 shares at June 30, 1997.....................................................           3      --
  Common stock, $.001 par value; authorized: 60,000,000 shares; issued and outstanding:
    2,295,416 shares at June 30, 1997 and 17,114,855 shares at June 30, 1998..............           2          17
  Additional paid-in capital..............................................................      23,904      53,286
  Accumulated deficit.....................................................................     (18,952)    (25,469)
  Notes receivable from stockholders......................................................      (1,088)     (1,088)
                                                                                            ----------  ----------
Total stockholders' equity................................................................       3,869      26,746
                                                                                            ----------  ----------
Total liabilities and stockholders' equity................................................  $  200,435  $  376,009
                                                                                            ----------  ----------
                                                                                            ----------  ----------
</TABLE>
 
                            See accompanying notes.
 
                                      F-3
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                            STATEMENTS OF OPERATIONS
 
               (IN THOUSANDS, EXCEPT SHARE AND PER SHARE AMOUNTS)
 
<TABLE>
<CAPTION>
                                                                                         YEAR ENDED JUNE 30,
                                                                                   -------------------------------
                                                                                     1996       1997       1998
                                                                                   ---------  ---------  ---------
<S>                                                                                <C>        <C>        <C>
Revenue..........................................................................  $  13,863  $  27,374  $  46,317
Operating expenses:
  Cost of providing services.....................................................      6,435     13,659     23,859
  General and administrative expenses............................................      2,054      4,282      6,727
  Research and development expenses..............................................      1,257      2,841      4,585
  Client acquisition costs.......................................................      5,388     11,706     17,858
  Acquisition of in-process technology...........................................        711     --         --
                                                                                   ---------  ---------  ---------
Total operating expenses.........................................................     15,845     32,488     53,029
                                                                                   ---------  ---------  ---------
Loss from operations.............................................................     (1,982)    (5,114)    (6,712)
Interest expense.................................................................       (473)    (1,190)      (557)
Other income.....................................................................         69         59        752
                                                                                   ---------  ---------  ---------
Net loss.........................................................................  $  (2,386) $  (6,245) $  (6,517)
                                                                                   ---------  ---------  ---------
                                                                                   ---------  ---------  ---------
Historical basic and diluted net loss per share (NOTE 1).........................  $   (4.91)
                                                                                   ---------
                                                                                   ---------
Shares used in computing historical basic and diluted net loss per share (NOTE
 1)..............................................................................        486
Pro forma basic and diluted net loss per share (NOTE 1)..........................             $   (0.59) $   (0.41)
                                                                                              ---------  ---------
                                                                                              ---------  ---------
Shares used in computing pro forma basic and diluted net loss per share (NOTE
 1)..............................................................................                10,533     15,722
</TABLE>
 
                            See accompanying notes.
 
                                      F-4
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                  STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT)
 
               (IN THOUSANDS, EXCEPT SHARE AND PER SHARE AMOUNTS)
<TABLE>
<CAPTION>
                                             PREFERRED STOCK                         COMMON STOCK
                                  -------------------------------------  -------------------------------------
                                                            ADDITIONAL                             ADDITIONAL
                                                              PAID-IN                                PAID-IN     ACCUMULATED
                                    SHARES       AMOUNT       CAPITAL      SHARES       AMOUNT       CAPITAL       DEFICIT
                                  -----------  -----------  -----------  -----------  -----------  -----------  -------------
<S>                               <C>          <C>          <C>          <C>          <C>          <C>          <C>
Balance at June 30, 1995........    2,613,301   $       2    $  11,682        20,142   $  --        $       3    $   (10,321)
Issuance of Series E preferred
 stock at $7.94 per share, net
 of issuance costs..............       40,000      --              317       --           --           --            --
Exercise of stock options.......      --           --           --         1,802,334           2          365        --
Issuance of preferred stock
 warrants.......................      --           --              200       --           --           --            --
Net loss........................      --           --           --           --           --           --             (2,386)
                                  -----------         ---   -----------  -----------       -----   -----------  -------------
Balance at June 30, 1996........    2,653,301           2       12,199     1,822,476           2          368        (12,707)
Issuance of Series F preferred
 stock at $17.40 per share, net
 of issuance costs..............      574,733           1        9,850       --           --           --            --
Exercise of stock options.......      --           --           --           472,940       -            1,166        --
Issuance of preferred stock
 warrants.......................      --           --              321       --           --           --            --
Net loss........................      --           --           --           --           --           --             (6,245)
                                  -----------         ---   -----------  -----------       -----   -----------  -------------
Balance at June 30, 1997........    3,228,034           3       22,370     2,295,416           2        1,534        (18,952)
Issuance of common stock in
 connection with initial public
 offering, net of offering
 costs..........................      --           --           --         4,312,500           4       27,005        --
Conversion of preferred stock
 into common stock..............   (3,288,034)         (3)     (22,370)    9,684,102          10       22,363        --
Exercise of warrants............      --           --           --           415,725           1          958        --
Exercise of stock options.......      --           --           --           236,998      --              317        --
Issuance of stock under employee
 stock purchase plan............      --           --           --           170,114      --            1,060        --
Issuance of warrants............      --           --           --           --           --               49        --
Net loss........................      --           --           --           --           --           --             (6,517)
                                  -----------         ---   -----------  -----------       -----   -----------  -------------
Balance at June 30, 1998........      --        $  --        $  --        17,114,855   $      17    $  53,286    $   (25,469)
                                  -----------         ---   -----------  -----------       -----   -----------  -------------
                                  -----------         ---   -----------  -----------       -----   -----------  -------------
 
<CAPTION>
 
                                      NOTES          TOTAL
                                   RECEIVABLE    STOCKHOLDERS'
                                      FROM          EQUITY
                                  STOCKHOLDERS     (DEFICIT)
                                  -------------  -------------
<S>                               <C>            <C>
Balance at June 30, 1995........    $  --          $   1,366
Issuance of Series E preferred
 stock at $7.94 per share, net
 of issuance costs..............       --                317
Exercise of stock options.......       --                367
Issuance of preferred stock
 warrants.......................       --                200
Net loss........................       --             (2,386)
                                  -------------  -------------
Balance at June 30, 1996........       --               (136)
Issuance of Series F preferred
 stock at $17.40 per share, net
 of issuance costs..............       --              9,851
Exercise of stock options.......       (1,088)            78
Issuance of preferred stock
 warrants.......................       --                321
Net loss........................       --             (6,245)
                                  -------------  -------------
Balance at June 30, 1997........       (1,088)         3,869
Issuance of common stock in
 connection with initial public
 offering, net of offering
 costs..........................       --             27,009
Conversion of preferred stock
 into common stock..............       --             --
Exercise of warrants............       --                959
Exercise of stock options.......       --                317
Issuance of stock under employee
 stock purchase plan............       --              1,060
Issuance of warrants............       --                 49
Net loss........................       --             (6,517)
                                  -------------  -------------
Balance at June 30, 1998........    $  (1,088)     $  26,746
                                  -------------  -------------
                                  -------------  -------------
</TABLE>
 
                            See accompanying notes.
 
                                      F-5
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                            STATEMENTS OF CASH FLOWS
 
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                                          YEAR ENDED JUNE 30,
                                                                                    -------------------------------
                                                                                      1996       1997       1998
                                                                                    ---------  ---------  ---------
<S>                                                                                 <C>        <C>        <C>
OPERATING ACTIVITIES
Net loss                                                                            $  (2,386) $  (6,245) $  (6,517)
Adjustments to reconcile net loss to net cash provided by (used in) operating
 activities:
  Depreciation and amortization...................................................      1,146      2,574      4,285
  Acquisition of in-process technology............................................        711     --         --
  Change in operating assets and liabilities:
  Accounts receivable, net........................................................       (521)    (1,002)      (136)
  Prepaid expenses and other current assets.......................................       (214)      (254)    (1,479)
  Other assets....................................................................        201     (1,782)     1,577
    Accounts payable..............................................................        360        438        661
    Accrued liabilities...........................................................        650      1,990      4,338
    Deferred revenue..............................................................       (149)       174        860
                                                                                    ---------  ---------  ---------
      Net cash provided by (used in) operating activities.........................       (202)    (4,107)     3,589
INVESTING ACTIVITIES
Acquisition of BeneSphere Administrators, Inc., net of cash acquired..............     --           (245)    --
Additional consideration paid in connection with the acquisition of BeneSphere
 Administrators, Inc..............................................................     --         --         (1,127)
Purchase of equipment, furniture and fixtures.....................................     (2,682)    (2,775)    (9,353)
Capitalization of software development costs......................................       (645)    (1,409)    (3,858)
Notes receivable from stockholders................................................     --           (295)    --
                                                                                    ---------  ---------  ---------
      Net cash used in investing activities.......................................     (3,327)    (4,724)   (14,338)
FINANCING ACTIVITIES
Borrowings under bank line of credit agreements...................................      5,934     24,727      6,874
Repayments of borrowings under line of credit agreements..........................     (3,478)   (23,831)   (11,632)
    Repayments under long term debt...............................................         --         --     (3,909)
    Proceeds from note payable....................................................      4,000         --         --
    Repayments under note payable.................................................         --       (534)        --
    Proceeds from notes payable to stockholders...................................        250        275         --
    Repayments under notes payable to stockholders................................       (227)      (275)      (250)
    Principal payments on capital lease obligations...............................       (128)      (454)      (955)
    Proceeds from issuance of preferred stock.....................................         --      9,851         --
    Proceeds from issuance of common stock........................................        367         78     29,345
                                                                                    ---------  ---------  ---------
Net cash provided by financing activities.........................................      6,718      9,837     19,473
                                                                                    ---------  ---------  ---------
Net increase in cash and cash equivalents.........................................      3,189      1,006      8,724
Cash and cash equivalents, at beginning of year...................................        852      4,041      5,047
                                                                                    ---------  ---------  ---------
Cash and cash equivalents, at end of year.........................................  $   4,041  $   5,047  $  13,771
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION
Cash paid during the period for interest..........................................  $     377  $   1,507  $     552
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
SUPPLEMENTAL SCHEDULE OF NON CASH INVESTING AND FINANCING ACTIVITIES
Purchase of equipment, furniture and fixtures under capital leases................  $     210  $   2,644  $     588
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
Issuance of warrants..............................................................  $     200  $     161  $      49
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
</TABLE>
 
                                      F-6
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                      STATEMENTS OF CASH FLOWS (CONTINUED)
 
                                 (IN THOUSANDS)
 
<TABLE>
<CAPTION>
                                                                                          YEAR ENDED JUNE 30,
                                                                                    -------------------------------
                                                                                      1996       1997       1998
                                                                                    ---------  ---------  ---------
<S>                                                                                 <C>        <C>        <C>
Notes receivable from stockholders issued in connection with stock option
 exercises........................................................................  $  --      $   1,088  $  --
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
ACQUISITION OF DIMENSION SOLUTIONS, INC.
  Issuance of Series E preferred stock............................................  $     317  $  --      $  --
  Liabilities assumed.............................................................        947     --         --
                                                                                    ---------  ---------  ---------
                                                                                    $   1,264  $  --      $  --
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
ACQUISITION OF BENESPHERE ADMINISTRATORS, INC.
  Issuance of warrants............................................................  $  --      $     160  $  --
  Liabilities assumed.............................................................     --          2,445     --
  Note payable to BeneSphere Administrators, Inc..................................     --            250     --
                                                                                    ---------  ---------  ---------
                                                                                    $  --      $   2,855  $  --
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
BeneSphere contingent consideration...............................................  $  --      $  --      $   2,208
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
</TABLE>
 
                            See accompanying notes.
 
                                      F-7
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                         NOTES TO FINANCIAL STATEMENTS
 
1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
 
OPERATIONS
 
    ProBusiness Services, Inc. (the "Company") provides employee administrative
services for large employers. The Company's primary service offerings are
payroll processing, payroll tax filing, human resources software and benefits
administration, including the enrollment and processing of flexible benefit
plans and COBRA programs.
 
    On May 23, 1996, the Company acquired substantially all of the business and
assets of Dimension Solutions, Inc. ("Dimension Solutions") for approximately
$1,300,000. The transaction was recorded under the purchase method of
accounting, and the results of operations of Dimension Solutions have been
included in the financial statements of the Company beginning May 24, 1996.
 
    On January 1, 1997, the Company acquired all of the outstanding stock of
BeneSphere Administrators, Inc. ("BeneSphere"), a Washington corporation. The
transaction was recorded under the purchase method of accounting, and the
results of operations of BeneSphere have been included in the financial
statements of the Company beginning January 2, 1997 (Note 10).
 
PAYROLL PROCESSING AND PAYROLL TAX FILING SERVICES
 
    In connection with its payroll tax filing services, the Company collects
funds from clients for payment of payroll taxes, holds such funds in financial
institution until payment is due (such funds being segregated from the Company's
other accounts), remits such funds to the appropriate taxing authorities, and
files related federal, state and local tax returns, coupons, or other required
payroll tax data ("payroll tax filings"). For such services, the Company derives
its payroll tax filing service revenue from fees charged and from interest
income it receives on payroll tax funds temporarily held pending remittance on
behalf of its clients to taxing authorities ("collected but unremitted payroll
tax funds"). These collected but unremitted payroll tax funds and the related
liability to clients for such funds are included in the accompanying balance
sheets as current assets and current liabilities. The amount of funds held under
these arrangements with customers may vary significantly during the year. The
Company invests collected but unremitted payroll tax funds in various financial
instruments which consisted of overnight U.S. government, agency and mortgage
backed repurchase agreements ($40,965,000), money market funds ($134,520,000)
and cash and cash equivalents ($2,141,000) at June 30, 1997, and of overnight
U.S. government, agency and mortgage backed repurchase agreements
($279,801,000), money market funds ($50,076,000) and cash and cash equivalents
($2,790,000) at June 30, 1998. As a result of the types of financial instruments
in which the Company invests, the carrying amount of such investments
approximates fair value. The Company's collected but unremitted payroll tax fund
investments are held primarily with one custodial financial institution.
Interest income earned on collected but unremitted payroll tax funds, which is
classified as revenue, amounted to approximately $1,896,000, $5,925,000, and
$11,521,000 for fiscal 1996, 1997 and 1998, respectively.
 
    The Company's payroll tax filing service is subject to various risks
resulting from errors and omissions in the payment of payroll taxes and related
payroll tax filings. The Company processes data received from client's and
remits funds along with any required payroll tax filings to the appropriate tax
authorities when due. Tracking, processing and paying such tax liabilities is
complex. Errors and omissions have occurred in the past and may occur in the
future in connection with such service. The Company is subject to cash penalties
imposed by tax authorities for late filings or underpayment of taxes. To date,
such penalties have not been significant. However, there can be no assurance
that any liabilities associated with such penalties
 
                                      F-8
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
will not have a material adverse effect on the Company's business, financial
condition or results of operations. At June 30, 1997 and 1998, the Company had
accrued approximately $586,000 and $971,000, respectively, for potential tax
penalties. There can be no assurance that the Company's accruals or insurance
for such penalties will be adequate. In addition, failure by the Company to make
timely or accurate payroll tax payments or filings when due may damage the
Company's reputation and adversely affect its relationships with existing
clients and its ability to gain new clients.
 
    The Company's payroll tax service is also dependent upon government
regulations, which are subject to continuous changes. Failure by the Company to
implement these changes into its services and technology in a timely manner
could have a material adverse effect on the Company's business, financial
condition and results of operations. In addition, since a significant portion of
the Company's revenue is derived from interest earned from the investment of
collected but unremitted payroll tax funds, changes in policies relating to
withholding federal or state income taxes or reduction in the time allowed for
taxpayers to remit payment of taxes owed to government authorities could have a
material adverse effect on the Company's business, financial condition and
results of operations.
 
    The Company's benefits administration services are subject to various risks
resulting from errors and omissions in processing and filing COBRA or other
benefit plan forms in accordance with governmental regulations and the
respective plans. The Company processes data received from employees and
employers and is subject to penalties for any late or misfiled plan forms. There
can be no assurance the Company's accruals or insurance for such penalties will
be adequate. In addition, failure to properly file plan forms would have a
material adverse effect on the Company's reputation, which could adversely
affect its relationships with existing clients and its ability to gain new
clients. The Company's benefits administration services are also dependent upon
government regulations which are subject to continuous changes that could reduce
or eliminate the need for benefits administration services.
 
    The Company has access to confidential information and to client funds. As a
result, the Company is subject to potential claims by its clients for the
actions of the Company's employees arising from damages to the client's business
or otherwise. There can be no assurance that the Company's fidelity bond and
errors and omissions insurance will be adequate to cover any such claims. Such
claims could have a material adverse effect on the Company's business, financial
condition and results of operations.
 
    The Company's operations are dependent on its ability to protect its
computer systems against damage from a major catastrophe (such as an earthquake
or other natural disaster), fire, power loss, security breach,
telecommunications failure or similar event. The Company currently conducts
substantially all of its payroll and payroll tax processing and production at
the Company's headquarters in Pleasanton, California. No assurance can be given
that the precautions that the Company has taken to protect itself from or
minimize the impact of such events will be adequate. Any damage to the Company's
data centers, failure of telecommunications links or breach of the security of
the Company's computer systems could result in an interruption of the Company's
operations or other loss which may not be covered by the Company's insurance.
Any such event could have a material adverse effect on the Company's business,
financial condition and results of operations.
 
INTEREST RATE SWAP AGREEMENTS
 
    During fiscal 1998, the Company entered into various interest rate swap
agreements with a financial institution. The purpose of these agreements is to
convert a portion of the interest the Company earns
 
                                      F-9
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
from collected but unremitted payroll tax funds from a floating to a fixed rate
basis. The Company considers these agreements to be for "other than trading
purposes" and has accounted for these agreements on an accrual basis, with each
net payment or receipt due or owed under each agreement recognized in earnings
during the period to which the payment or receipt relates, with no recognition
on the balance sheet of the fair value of the agreements. At June 30, 1998, the
aggregate fair value of these agreements was $432,000.
 
    These agreements, with fixed interest rates between 5.736% and 5.905%, each
have a term of two years, one of which has a cancellation option after one year,
and expire at various dates through April 2000. Interest is paid or received
based upon the difference in the fixed interest rate and the contractual
floating rate option times the contractual notional balance. The actual notional
balance varies on a monthly basis due to fluctuations in projected holdings of
collected but unremitted payroll tax funds. At June 30, 1998, the notional
balance was $204,700,000 and the average monthly notional balance for the
remaining term of the agreements was $242,000,000. The agreements require
collateral if interest rates increase and certain other conditions are met as
defined in the agreements. At June 30, 1998, no collateral was required.
 
USE OF ESTIMATES
 
    The preparation of financial statements in conformity with generally
accepted accounting principles requires management to make estimates and
assumptions that affect the reported amounts of assets and liabilities and
disclosure of contingent assets and liabilities and the reported amounts of
revenues and expenses during the period. Such estimates include, but are not
limited to, provisions for doubtful accounts and penalties and interest relating
to payroll tax processing and estimates regarding the recoverability of
capitalized software. Actual results could differ from these estimates.
 
CASH AND CASH EQUIVALENTS
 
    The Company considers all highly liquid investments with a maturity of three
months or less at the time of purchase to be cash equivalents. Cash and cash
equivalents have a carrying amount which approximates fair value. The Company's
cash, cash equivalents and payroll tax funds invested are held primarily with
two financial institutions.
 
EQUIPMENT, FURNITURE AND FIXTURES
 
    Equipment, furniture and fixtures are stated at cost, net of accumulated
depreciation and amortization. Depreciation of equipment, furniture and fixtures
is computed using the straight-line method over the estimated useful lives of
the assets which range from three to seven years. Leasehold improvements and
assets under capital leases are amortized over the shorter of the life of the
asset or the term of the lease.
 
REVENUE RECOGNITION
 
    Revenue from payroll processing and payroll tax filing services under client
contracts is recognized as the services are performed. Interest income earned on
unremitted payroll tax funds invested is recognized as earned.
 
    The Company's sales are primarily to customers in the United States. Credit
evaluations are performed as necessary and the Company does not require
collateral from customers.
 
                                      F-10
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
SOFTWARE DEVELOPMENT COSTS
 
    The Company accounts for software development costs in accordance with
Statement of Financial Accounting Standards No. 86 "Accounting for the Costs of
Computer Software to be Sold, Leased or Otherwise Marketed."
 
    The Company capitalizes software development costs incurred after
establishing technological feasibility of the product prior to the general
release of the service using the product. Costs incurred in connection with the
enhancement of the Company's existing products or after the general release of
the service using the product are expensed in the current period and included in
the research and development costs within the statement of operations. The
Company amortizes the capitalized software development costs using the greater
of the straight-line basis over the estimated product life, which is generally a
36 month period, or the ratio of current revenue to the total of current revenue
and anticipated future revenue over the life of the related product. Such
amortization is included in cost of providing services within the statement of
operations.
 
ACCOUNTING FOR STOCK-BASED COMPENSATION
 
    The Company accounts for employee stock options in accordance with
Accounting Principles Board Opinion No. 25, "Accounting for Stock Issued to
Employees" ("APB 25") and has adopted the "disclosure only" alternative as
described in FAS No. 123, "Accounting for Stock-Based Compensation" ("FAS 123")
(Note 7).
 
IMPACT OF RECENTLY ISSUED ACCOUNTING STANDARDS
 
    In June 1997, the Financial Accounting Standards Board ("FASB") issued FAS
No. 130, "Reporting Comprehensive Income" ("FAS 130"), and FAS No. 131,
"Disclosure about Segments of an Enterprise and Related Information" ("FAS
131"). The Company is required to adopt these statements in fiscal 1999. FAS 130
establishes new standards for reporting and displaying comprehensive income and
its components. FAS 131 requires disclosure of certain information regarding
operating segments, products and services, geographic areas of operation and
major customers. The Company has not reached a conclusion as to the appropriate
segments, if any, it will be required to report to comply with the provisions of
FAS 131. Adoption of these statements is not expected to have a significant
impact on the Company's financial position, results of operations or cash flows.
 
    In June 1998, the FASB issued FAS No. 133, "Accounting for Derivative
Instruments and Hedging Activities" ("FAS 133"). The Company is required to
adopt FAS 133 in fiscal 2000. FAS 133 established methods of accounting for
derivative financial instruments and hedging activities related to those
instruments as well as other hedging activities. The Company has not yet
determined what the effect of FAS 133 will be on the operations and financial
position of the Company.
 
RECLASSIFICATIONS
 
    Certain prior year balances have been reclassified to conform to the current
year presentation.
 
BASIC AND DILUTED NET LOSS PER SHARE (HISTORICAL AND PRO FORMA)
 
    Historical net loss per share is presented under the requirements of FAS No.
128, "Earnings Per Share" ("FAS 128"). FAS 128 replaced the previously reported
primary and fully diluted earnings per share with basic and diluted earnings per
share. Unlike primarily earnings per share, basic earnings per share
 
                                      F-11
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
1. SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
excludes any dilutive effects of options, warrants, convertible securities and
shares subject to repurchase. Diluted earnings per share is very similar to the
previously reported fully diluted earnings per share. Common stock equivalent
shares from convertible preferred stock and from stock options and warrants are
not included in the calculation of diluted net loss per share as the effect is
anti-dilutive. All net loss per share amounts for all periods have been
presented to conform to the FAS 128 requirements.
 
    In February 1998, Staff Accounting Bulletin No. 98 ("SAB 98") was issued and
amends the existing Securities and Exchange Commission ("SEC") staff guidance
primarily to give effect to FAS 128. Under SAB 98, certain shares of convertible
preferred stock, options and warrants to purchase shares of common stock, issued
at prices below the per share price of shares sold in the company's initial
public offering in September 1997 and previously included in the computations of
shares used in computing net loss per share pursuant to previous staff
accounting bulletins have now been excluded from the computation.
 
    Pro forma net loss per share has been computed as described above and also
gives effect, under SEC guidance, to the conversion of preferred stock to common
stock not included above that automatically converted upon completion of the
Company's initial public offering, using the if-converted method.
 
    A reconciliation of shares used in the calculation of historical and pro
forma basic and diluted net loss per share follows (in thousands except share
and per share information):
 
<TABLE>
<CAPTION>
                                                                                          YEAR ENDED JUNE 30,
                                                                                    -------------------------------
                                                                                      1996       1997       1998
                                                                                    ---------  ---------  ---------
<S>                                                                                 <C>        <C>        <C>
Historical:
  Net loss........................................................................  $  (2,386) $  (6,245) $  (6,517)
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
  Weighted average shares of common stock outstanding used in computing basic and
    diluted net loss per share....................................................        486      1,999     13,596
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
  Basic and diluted net loss per share............................................  $   (4.91) $   (3.12) $   (0.48)
                                                                                    ---------  ---------  ---------
                                                                                    ---------  ---------  ---------
Pro forma:
  Net loss........................................................................             $  (6,245) $  (6,517)
                                                                                               ---------  ---------
                                                                                               ---------  ---------
  Shares used in computing basic and diluted net loss per share (from above)......                 1,999     13,596
  Pro forma adjustment to reflect the effect of the conversion of preferred stock
    from the date of issuance.....................................................                 8,534      2,126
                                                                                               ---------  ---------
  Weighted average shares used in computing pro forma basic and diluted net loss
    per share.....................................................................                10,533     15,722
                                                                                               ---------  ---------
                                                                                               ---------  ---------
  Pro forma basic and diluted net loss per share..................................             $   (0.59) $   (0.41)
                                                                                               ---------  ---------
                                                                                               ---------  ---------
</TABLE>
 
    If the Company had reported net income, the calculation of diluted earnings
per share (historical and pro forma) would have included the shares used in the
computation of historical and pro forma net loss per share as well as an
additional 356,000, 466,000 and 797,000 common equivalent shares related to the
outstanding options and warrants not included above (determined using the
treasury stock method) for fiscal 1996, 1997 and 1998, respectively.
 
                                      F-12
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
2. EQUIPMENT, FURNITURE AND FIXTURES
 
    Equipment, furniture and fixtures consist of the following (in thousands):
 
<TABLE>
<CAPTION>
                                                                               JUNE 30,
                                                                        ----------------------
                                                                           1997        1998
                                                                        ----------  ----------
<S>                                                                     <C>         <C>
Equipment and leasehold improvements..................................  $    9,981  $   18,172
Furniture and fixtures................................................       1,973       3,239
                                                                        ----------  ----------
                                                                            11,954      21,411
Less accumulated depreciation and amortization........................      (4,331)     (7,453)
                                                                        ----------  ----------
                                                                        $    7,623  $   13,958
                                                                        ----------  ----------
                                                                        ----------  ----------
</TABLE>
 
    Equipment, furniture and fixtures include amounts for assets acquired under
capital leases, principally production, office and computer equipment, of
$3,515,000 and $3,863,000 at June 30, 1997 and 1998, respectively. Accumulated
amortization of these assets was $854,000 and $1,712,000 at June 30, 1997 and
1998, respectively.
 
3. LONG-TERM DEBT
 
LINE OF CREDIT AGREEMENTS
 
    On June 30, 1998, the Company executed an Amended and Restated Loan and
Security Agreement with a financial institution. The agreement provides for
borrowings that are limited to the lesser of $20,000,000, or the sum of five
times the Company's average monthly net collections, as defined in the
agreement, plus the lesser of five times the Company's average monthly
collections of the interest on tax investment funds as defined in the agreement
or $5,000,000, plus $1,500,000. The agreement superseded all previous line of
credit agreements and amendments thereto with the financial institution that
existed as of June 30, 1997.
 
    At June 30, 1998, no borrowings were outstanding under the agreement and the
amount available for borrowing under the agreement was approximately
$20,000,000. Borrowings outstanding under the agreement bear interest at the
bank's prime rate plus 1% (9.5% at June 30, 1998) and are collateralized by
substantially all of the Company's assets not otherwise encumbered. The
financial covenants of the agreement require the Company to maintain minimum net
worth and earnings to debt service ratios. The agreement expires on December 31,
2000, and is subject to automatic and continuous renewal unless termination
notice is given by either party in accordance with the agreement. All borrowings
outstanding at June 30, 1997 totaling $4,758,000, under the previous agreements,
were paid in September 1997 with the proceeds from the Company's initial public
offering.
 
SUBORDINATED NOTES PAYABLE
 
    In October 1995 and December 1995, the Company issued $1,100,000 and
$2,900,000, respectively of subordinated notes payable to investors. The
subordinated notes and interest accrued thereon were repaid in their entirety in
September 1997 with proceeds from the Company's initial public offering.
 
                                      F-13
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
3. LONG-TERM DEBT (CONTINUED)
NOTE PAYABLE TO STOCKHOLDER
 
    A $250,000 subordinated note payable to a stockholder was assumed in the
acquisition of Dimension Solutions. The note was repaid in fiscal 1998.
 
4. LEASE OBLIGATIONS
 
    The Company leases its facilities and various equipment under non-cancelable
operating leases which expire at various dates through 2010. The Company is also
obligated under a number of capital equipment leases expiring at various dates
through 2003. The future minimum lease payments under capital and operating
leases subsequent to June 30, 1998 are summarized as follows (in thousands):
 
<TABLE>
<CAPTION>
                                                                            CAPITAL    OPERATING
                                                                            LEASES      LEASES
                                                                           ---------  -----------
<S>                                                                        <C>        <C>
Year ending June 30,
  1999...................................................................  $   1,180   $   3,476
  2000...................................................................      1,029       4,067
  2001...................................................................        297       4,434
  2002...................................................................        158       4,402
  2003...................................................................        158       4,186
  Thereafter.............................................................     --          25,710
                                                                           ---------  -----------
    Total minimum lease payments.........................................      2,822   $  46,275
                                                                                      -----------
                                                                                      -----------
Less amounts representing interest.......................................        518
                                                                           ---------
Present value of net minimum capital lease obligations...................      2,304
Less current portion.....................................................        890
                                                                           ---------
                                                                           $   1,414
                                                                           ---------
                                                                           ---------
</TABLE>
 
    Rent expense was approximately $707,000, $1,487,000 and $3,028,000 for
fiscal 1996, 1997 and 1998, respectively.
 
5. INCOME TAXES
 
    As of June 30, 1998, the Company had federal and state net operating loss
carryforwards of approximately $17,200,000 and $1,200,000, respectively. The
Company also had federal and state research and development tax credit
carryforwards of approximately $1,057,000 and $442,000, respectively. The
federal net operating loss and credit carryforwards will expire at various dates
beginning with the fiscal year ending 1999 through 2013, if not utilized. The
state net operating loss carryforwards will expire at various dates beginning
with the fiscal 1999 through 2003, if not utilized. The state credit
carryforwards do not expire.
 
    Utilization of the net operating losses and credits may be subject to a
substantial annual limitation due to the ownership change limitations provided
by the Internal Revenue Code of 1986, as amended (the "Code"), and similar state
provisions. The annual limitation may result in the expiration of net operating
losses and credits before utilization.
 
                                      F-14
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
5. INCOME TAXES (CONTINUED)
    Significant components of the Company's deferred tax assets and liabilities
are as follows (in thousands):
 
<TABLE>
<CAPTION>
                                                                                 JUNE 30,
                                                                           --------------------
                                                                             1997       1998
                                                                           ---------  ---------
<S>                                                                        <C>        <C>
Deferred tax assets:
  Net operating loss carryforwards.......................................  $   4,965  $   5,951
  Research and development credit carryforwards..........................        650      1,499
  Depreciation...........................................................        428      1,010
  Accrued liabilities and allowances.....................................        330      2,147
                                                                           ---------  ---------
Gross deferred tax assets................................................      6,373     10,607
Less valuation allowance.................................................     (5,988)    (9,224)
                                                                           ---------  ---------
Deferred tax assets......................................................        385      1,383
Deferred tax liabilities:
  Capitalized software development costs.................................       (313)    (1,338)
  Other..................................................................        (72)       (45)
                                                                           ---------  ---------
Gross deferred tax liabilities...........................................       (385)    (1,383)
                                                                           ---------  ---------
Net deferred taxes.......................................................  $  --      $  --
                                                                           ---------  ---------
                                                                           ---------  ---------
</TABLE>
 
    A valuation allowance has been established and, accordingly, no benefit has
been recognized for the Company's net operating losses and other deferred tax
assets. The Company believes that, based on a number of factors, the available
objective evidence creates sufficient uncertainty regarding the realizability of
the deferred tax assets such that a full valuation allowance has been recorded.
These factors include the Company's history of net losses since its inception
and expected near-term future losses. The Company will continue to assess the
realizability of the deferred tax assets based on actual and forecasted
operating results. The net valuation allowance increased by $2,391,000 and
$3,236,000, respectively during fiscal 1997 and 1998.
 
6. STOCKHOLDERS' EQUITY
 
    In September 1997, the Company completed its initial public offering of
common stock. The offering consisted of 3,750,000 shares of common stock issued
to the public at $7.33 per share. Upon the closing of the initial public
offering, all outstanding shares of preferred stock were converted into common
stock.
 
    In October 1997, the underwriters exercised an option to purchase an
additional 562,500 shares of common stock at the initial public offering price
of $7.33 per share to cover over-allotments in connection with the initial
public offering.
 
                                      F-15
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
6. STOCKHOLDERS' EQUITY (CONTINUED)
WARRANTS
 
    The following tables represents a summary of warrants outstanding as of June
30, 1998:
 
<TABLE>
<CAPTION>
                                                           NUMBER OF
                                        EXERCISE PRICE    SHARES JUNE
DATE ISSUED         EXPIRATION             PER SHARE       30, 1998
- ------------------  ------------------  ---------------  -------------
<S>                 <C>                 <C>              <C>
April 1996          April 2001             $    2.65           28,500
October 1996        October 2001                2.65           28,500
November 1996       September 2002              2.65           67,500
January 1997        January 2002                6.00           75,000
July 1997           July 2002                   6.00           30,000
                                                         -------------
                                                              229,500
                                                         -------------
                                                         -------------
</TABLE>
 
    In connection with the Company's initial public offering, the Company issued
367,288 shares of common stock upon the exercise of warrants, a portion of which
were exercised pursuant to a net exercise provisions, for total proceeds of
$923,000. In addition, during fiscal 1998, the Company issued 48,437 shares of
common stock upon exercise of warrants, a portion of which were exercised
pursuant to net exercise provisions, for a total of $36,000. All other warrants
noted as exercised above were exercised pursuant to net exercise provisions.
 
STOCK SPLIT
 
    On July 23, 1998, the Board of Directors approved a three-for-two split of
its $.001 par value common stock in the form of a 50 percent distribution to
stockholders of record as of July 31, 1998. As a result of the stock split,
authorized and outstanding common shares increased 50 percent and capital in
excess of par was reduced by the par value of the additional common shares
issued. The rights of the holders of these securities were not otherwise
modified. All references in the financial statements to number of shares, per
share amounts, stock option data and market prices of the Company's common stock
have been restated for the effect of the stock split.
 
7. STOCK OPTION AND STOCK PURCHASE PLANS
 
STOCK OPTION PLANS
 
    The Company's 1989 Stock Option Plan (the "1989 Plan") provided for the
granting to employees (including officers and employee directors) of "incentive
stock options" within the meaning of the Code and for the granting to employees,
directors and consultants of nonstatutory stock options. In February 1997, the
Board of Directors of the Company increased the shares available for future
grants under the 1989 Plan by 2,063,649 for a total of 4,480,872. Options
granted under the 1989 Plan before the effective date of the amendment and
restatement to the 1996 Plan in September, 1997, described below, remain
outstanding in accordance with their terms, but no further options were granted
under the 1989 Plan after the effective date of the amendment and restatement to
the 1996 Plan.
 
    In 1996, the Company established the 1996 Executive Stock Option Plan
("Executive Plan") which provides for stock options to employees and
consultants. Under the Executive Plan, the Board of Directors may grant
nonstatutory stock options to employees and consultants and incentive stock
options to
 
                                      F-16
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
7. STOCK OPTION AND STOCK PURCHASE PLANS (CONTINUED)
employees only. The Company has reserved 1,125,000 shares of common stock for
exercise of stock options under the Executive Plan. The grant of incentive stock
option to an employee who owns stock representing more than 10% of the voting
power of all classes of stock of the Company must be no less than 110% of the
fair market value per share on the date of grant. Fair market value is
determined by the Board of Directors. For all other employees the options must
be no less than 100% of the fair market value per share on the date of grant.
All nonstatutory stock options granted are at a price that is determined by the
Board of Directors. The options generally expire ten years from the date of
grant and are exercisable as determined by the Board of Directors.
 
    In November 1996, the Board of Directors and stockholders approved,
effective upon the initial public offering, an amendment and restatement of the
Executive Plan to rename the 1996 Executive Stock Option Plan to the 1996 Stock
Option Plan (the "1996 Plan") and authorized an increase in the number of shares
reserved for issuance under the 1996 Plan of any unused or canceled shares under
the 1989 Plan, and an annual increase equal to the lesser of (a) 375,000 shares,
(b) 2% of the outstanding shares of common stock on such date or (c) a lesser
amount determined by the Board. The 1996 Plan provides for grants to employees
(including officers and employee directors) of incentive stock options and for
the granting to employees, directors and consultants of nonqualified stock
options. Notes receivable for the purchase of common stock are included in
stockholders' equity (deficit).
 
    A summary of the activity under the 1989 and 1996 Plans is set forth below:
 
<TABLE>
<CAPTION>
                                                                      OUTSTANDING OPTIONS
                                                                  ----------------------------
                                                                                  WEIGHTED
                                                                                   AVERAGE
                                                                   NUMBER OF   EXERCISE PRICE
                                                                    SHARES        PER SHARE
                                                                  -----------  ---------------
<S>                                                               <C>          <C>
Outstanding at June 30, 1995....................................    1,528,344     $    0.17
  Granted.......................................................    1,583,895          0.29
  Exercised.....................................................   (1,802,334)         0.22
  Canceled......................................................     (345,703)         0.22
                                                                  -----------        ------
Outstanding at June 30, 1996....................................      964,202          0.27
  Granted.......................................................      994,005          4.83
  Exercised.....................................................     (472,940)         2.39
  Canceled......................................................     (171,603)         2.51
                                                                  -----------        ------
Outstanding at June 30, 1997....................................    1,313,664          2.67
  Granted.......................................................      907,875         11.82
  Exercised.....................................................     (236,998)         1.34
  Canceled......................................................     (184,125)         7.12
                                                                  -----------        ------
Outstanding at June 30, 1998....................................    1,800,416     $    6.97
                                                                  -----------        ------
                                                                  -----------        ------
</TABLE>
 
                                      F-17
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
7. STOCK OPTION AND STOCK PURCHASE PLANS (CONTINUED)
 
    As of June 30, 1998, options to purchase 414,884 shares of common stock were
vested and exercisable at an average exercise price of $2.03 per share and
options to purchase 1,277,510 shares were available for future grant. As of June
30, 1998, options to purchase approximately 317,000 shares of common stock had
been exercised which are subject to repurchase.
 
    The weighted-average fair value of options granted during fiscal 1996, 1997
and 1998 was $0.06, $1.01 and $6.98 per share, respectively.
 
    The following table summarizes information concerning currently outstanding
and exercisable options at June 30, 1998:
 
<TABLE>
<CAPTION>
                                                   OUTSTANDING
                                     ----------------------------------------       EXERCISABLE
                                                    WEIGHTED                   ----------------------
                                                     AVERAGE       WEIGHTED                WEIGHTED
                                                    REMAINING       AVERAGE                 AVERAGE
                                                   CONTRACTUAL     EXERCISE                EXERCISE
EXERCISE PRICE                         SHARES         LIFE           PRICE      SHARES       PRICE
- -----------------------------------  ----------  ---------------  -----------  ---------  -----------
<S>                                  <C>         <C>              <C>          <C>        <C>
$0.13 - $0.26......................     399,084          7.10      $    0.26     231,235   $    0.25
$0.83 - $4.83......................     399,707          8.41      $    4.02     141,932   $    3.75
$5.83 - $6.00......................     620,250          9.03      $    5.91      40,967   $    5.86
$12.08 - $31.17....................     381,375          9.57      $   18.84         750   $   19.33
                                     ----------                                ---------  -----------
                                      1,800,416                                  414,884
                                     ----------                                ---------
                                     ----------                                ---------
</TABLE>
 
STOCK-BASED COMPENSATION
 
    As permitted under FAS 123, the Company has elected to continue to follow
APB 25 in accounting for stock-based awards to employees. Under APB 25, the
Company has not recognized any compensation expense with respect to such awards,
since the exercise price of the stock options awarded are equal to the fair
market value of the underlying security on the grant date.
 
    Disclosure of information regarding net loss and net loss per share is
required by FAS 123, which also requires that the information be determined on
an "as adjusted" basis as if the Company had accounted for its stock-based
awards to employees granted subsequent to June 30, 1995, under the fair value
method of FAS 123. The fair value of the Company's stock-based awards to
employees was estimated as of the date of the grant using a Black-Scholes option
pricing model. Limitations on the effectiveness of the Black-Scholes option
valuation model are that it was developed for use in estimating the fair value
of traded options which have no vesting restrictions and are fully transferable
and that the model requires the use of highly subjective assumptions including
expected stock price volatility. Because the Company's stock-based awards to
employees have characteristics significantly different from those of traded
options and because changes in the subjective input assumptions can materially
affect the fair value estimate, in management's opinion, the existing models do
not necessarily provide a reliable single measure of the fair value of its
stock-based awards to employees. The Company has plans which award employees
stock options. These
 
                                      F-18
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
7. STOCK OPTION AND STOCK PURCHASE PLANS (CONTINUED)
plans are discussed in the note above. The fair value of the Company's
stock-based awards to employees was estimated using the following
weighted-average assumptions:
 
<TABLE>
<CAPTION>
                                                                         YEAR ENDED JUNE 30,
                                                                   -------------------------------
                                                                     1996       1997       1998
                                                                   ---------  ---------  ---------
<S>                                                                <C>        <C>        <C>
Expected life (in years).........................................          3          2          2
Expected volatility..............................................      0.001      0.001      0.746
Risk free interest rate..........................................       6.2%       6.2%       5.5%
Expected dividend yield..........................................       0.0%       0.0%       0.0%
</TABLE>
 
    For disclosure purposes, the adjusted estimated fair value of the Company's
stock-based awards to employees is amortized over the vesting period for
options. The Company's adjusted information follows (in thousands, except for
per share information):
 
<TABLE>
<CAPTION>
                                                                      YEAR ENDED JUNE 30,
                                                                -------------------------------
                                                                  1996       1997       1998
                                                                ---------  ---------  ---------
<S>                                                             <C>        <C>        <C>
Net loss, as reported.........................................  $  (2,386) $  (6,245) $  (6,517)
                                                                ---------  ---------  ---------
                                                                ---------  ---------  ---------
Net loss, as adjusted.........................................  $  (2,403) $  (6,355) $  (7,427)
                                                                ---------  ---------  ---------
                                                                ---------  ---------  ---------
Historical net loss per share, as reported....................  $   (4.91) $   (3.12) $   (0.48)
                                                                ---------  ---------  ---------
                                                                ---------  ---------  ---------
Historical net loss per share, as adjusted....................  $   (4.94) $   (3.18) $   (0.55)
                                                                ---------  ---------  ---------
                                                                ---------  ---------  ---------
Pro forma net loss per share, as reported.....................             $   (0.59) $   (0.41)
                                                                           ---------  ---------
                                                                           ---------  ---------
Pro forma net loss per share, as adjusted.....................             $   (0.60) $   (0.47)
                                                                           ---------  ---------
                                                                           ---------  ---------
</TABLE>
 
    Because FAS 123 is applicable only to the Company's stock-based awards
granted subsequent to June 30, 1995, its effect will not be fully reflected
until approximately fiscal 1999.
 
1997 EMPLOYEE STOCK PURCHASE PLAN
 
    The Company's 1997 Employee Stock Purchase Plan (the "Purchase Plan") was
adopted by the Board of Directors in November 1996 and amended in August 1997,
for which employees who work a minimum of 20 hours per week and for five months
in any calendar year are eligible. There were 750,000 shares of common stock
authorized for issuance under the Purchase Plan with an annual increase to be
added on each anniversary date of the adoption of the Purchase Plan equal to the
lesser of (a) 225,000 shares, (b) 1.5% of the outstanding shares on such date or
(c) a lesser amount determined by the Board of Directors. As of June 30, 1998,
170,114 shares had been issued for the first purchase. Under the Purchase Plan,
the Company's employees, subject to certain restrictions, may purchase shares of
common stock at the lesser of 85 percent of the fair market value at either the
beginning of each two-year offering period or the end of each six-month purchase
period within the two-year offering period. Plan purchases are limited to 10% of
each employee's compensation.
 
                                      F-19
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
8. EMPLOYEE BENEFIT PLAN
 
    The Company maintains a tax deferred savings plan under section 401(k) of
the Code (the "Plan"), for the benefit of certain qualified employees. Employees
may elect to contribute to the Plan, through payroll deductions of up to 18% of
their compensation, subject to certain limitations. The Company, at its
discretion, may make additional contributions. The Company did not make any
contributions to the Plan in fiscal 1996, 1997 or 1998.
 
9. BALANCE SHEET DETAIL
 
    Other assets consist of the following (in thousands):
 
<TABLE>
<CAPTION>
                                                                                 JUNE 30,
                                                                           --------------------
                                                                             1997       1998
                                                                           ---------  ---------
<S>                                                                        <C>        <C>
Capitalized software development costs...................................  $   1,716  $   5,247
Deferred financing costs.................................................      1,043     --
Prepaid lease expense....................................................        161        133
Notes receivable from employees..........................................        376        422
Goodwill and other intangible assets.....................................      2,627      4,625
Deposits and other.......................................................      1,097        452
                                                                           ---------  ---------
                                                                           $   7,020  $  10,879
                                                                           ---------  ---------
                                                                           ---------  ---------
</TABLE>
 
    Accumulated amortization for capitalized software development costs was
approximately $475,000 and $802,000 at June 30, 1997 and 1998, respectively.
Accumulated amortization for goodwill and other intangible assets was
approximately $80,000 and $384,000 at June 30, 1997 and 1998, respectively.
 
    In January 1997, the Company advanced $250,000 in the form of a note
receivable from a stockholder who is also an executive officer. The note is due
in January 2001, bears interest at 6.10% and is full recourse.
 
    Accrued liabilities consist of the following (in thousands):
 
<TABLE>
<CAPTION>
                                                                                 JUNE 30,
                                                                           --------------------
                                                                             1997       1998
                                                                           ---------  ---------
<S>                                                                        <C>        <C>
Accrued expenses.........................................................  $   2,773  $   4,408
Accrued tax penalties....................................................        586        971
Accrued payroll and related expenses.....................................      1,361      3,322
Accrued acquisition costs................................................        144     --
Accrued BeneSphere contingent consideration (Note 10)....................     --          1,081
Other....................................................................        120        621
                                                                           ---------  ---------
                                                                           $   4,984  $  10,403
                                                                           ---------  ---------
                                                                           ---------  ---------
</TABLE>
 
10. BUSINESS ACQUISITIONS
 
    In January 1997, the Company acquired all of the outstanding stock of
BeneSphere. The purchase price consisted of $500,000 in cash, of which $250,000
was paid upon closing and $250,000 was paid in April 1997, warrants to purchase
75,000 shares of the Company's common stock at a price of $6.00 per
 
                                      F-20
<PAGE>
                           PROBUSINESS SERVICES, INC.
 
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
 
10. BUSINESS ACQUISITIONS (CONTINUED)
share and with an estimated fair value of $160,000, the assumption of $2,445,000
of BeneSphere's liabilities (including acquisition costs) plus additional
contingent consideration based on BeneSphere's revenues in excess of certain
base amounts, as defined in the agreement, over the next two calendar years
following the acquisition which cannot exceed $4,500,000. The contingent
consideration is payable in cash in four quarterly payments beginning April 1,
1998 for the calendar year 1997 payment and April 1, 1999 for the calendar year
1998 payment. Interest shall accrue at a rate of 9% per annum on all earned but
unpaid balances.
 
    A summary of the purchase price allocation is as follows (in thousands):
 
<TABLE>
<CAPTION>
<S>                                                                                    <C>
Current and other assets.............................................................  $     517
Goodwill.............................................................................      2,278
Customer list........................................................................        310
                                                                                       ---------
Total purchase price allocation......................................................  $   3,105
                                                                                       ---------
                                                                                       ---------
</TABLE>
 
    Goodwill arising from the acquisition is being amortized on a straight-line
basis over 20 years.
 
    In January 1998, the Company accrued an additional $2,208,000 of contingent
consideration and recorded goodwill in the same amount related to the BeneSphere
acquisition as described above. As of June 30, 1998, the Company had made two
quarterly payments relating to the contingent consideration and had a remaining
outstanding balance of $1,081,000 which is classified as accrued liabilities.
 
11. SUBSEQUENT EVENTS
 
PUBLIC OFFERING
 
    On July 23, 1998, the Board of Directors authorized the Company to proceed
with a public offering of the Company's common stock.
 
                                      F-21
<PAGE>
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
    NO DEALER, SALESPERSON OR ANY OTHER PERSON HAS BEEN AUTHORIZED TO GIVE ANY
INFORMATION OR TO MAKE ANY REPRESENTATIONS IN CONNECTION WITH THIS OFFERING
OTHER THAN THOSE CONTAINED IN THIS PROSPECTUS, AND, IF GIVEN OR MADE, SUCH
INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON AS HAVING BEEN AUTHORIZED
BY THE COMPANY OR ANY OF THE UNDERWRITERS. THIS PROSPECTUS DOES NOT CONSTITUTE
AN OFFER TO SELL OR A SOLICITATION OF AN OFFER TO BUY ANY OF THE SECURITIES
OFFERED HEREBY BY ANYONE IN ANY JURISDICTION IN WHICH SUCH OFFER OR SOLICITATION
IS NOT AUTHORIZED OR IN WHICH THE PERSON MAKING SUCH OFFER OR SOLICITATION IS
NOT QUALIFIED TO DO SO OR TO ANY PERSON TO WHOM IT IS UNLAWFUL TO MAKE SUCH
OFFER OR SOLICITATION. NEITHER THE DELIVERY OF THIS PROSPECTUS NOR ANY SALE MADE
HEREUNDER SHALL, UNDER ANY CIRCUMSTANCES, CREATE ANY IMPLICATION THAT ANY
INFORMATION CONTAINED HEREIN IS CORRECT AS OF ANY TIME SUBSEQUENT TO THE DATE OF
THIS PROSPECTUS.
 
                            ------------------------
 
                               TABLE OF CONTENTS
 
<TABLE>
<CAPTION>
                                                                            PAGE
                                                                            ----
<S>                                                                         <C>
Prospectus Summary........................................................    3
Risk Factors..............................................................    5
Safe Harbor for Forward-Looking Statements................................   14
Use of Proceeds...........................................................   15
Dividend Policy...........................................................   15
Price Range of Common Stock...............................................   15
Capitalization............................................................   16
Dilution..................................................................   17
Selected Financial Data...................................................   18
Management's Discussion and Analysis of Financial Condition and Results of
 Operations...............................................................   19
Business..................................................................   27
Management................................................................   37
Certain Transactions......................................................   44
Principal Stockholders....................................................   45
Description of Capital Stock..............................................   47
Shares Eligible for Future Sale...........................................   50
Underwriting..............................................................   52
Legal Matters.............................................................   53
Experts...................................................................   53
Additional Information....................................................   53
Index to Financial Statements.............................................  F-1
</TABLE>
 
                                2,475,000 SHARES
 
                                     [LOGO]
 
                                  COMMON STOCK
 
                                ---------------
 
                                   PROSPECTUS
 
                                         , 1998
 
                                 --------------
 
                            WILLIAM BLAIR & COMPANY
 
                                  BANCAMERICA
                               ROBERTSON STEPHENS
 
                                    SG COWEN
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
                                    PART II
 
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 13. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION
 
    The following table sets forth the costs and expenses, other than
underwriting discounts and commissions, payable by the Company in connection
with the sale and distribution of Common Stock being registered. All amounts are
estimates except the registration fee and the NASD filing fee.
 
<TABLE>
<CAPTION>
                                                                                    AMOUNT TO
                                                                                     BE PAID
                                                                                    ----------
<S>                                                                                 <C>
Registration fee..................................................................  $   32,450
NASD filing fee...................................................................      11,500
Printing expenses.................................................................     120,000
Legal fees and expenses...........................................................     200,000
Accounting fees and expenses......................................................     200,000
Blue sky fees and expenses........................................................       5,000
Transfer agent and registrar fees and expenses....................................       5,000
Nasdaq National Market application and listing fees...............................      17,500
Miscellaneous.....................................................................      78,550
                                                                                    ----------
    Total.........................................................................  $  670,000
</TABLE>
 
ITEM 14. INDEMNIFICATION OF DIRECTORS AND OFFICERS
 
    Reference is made to Article Ninth of the Amended and Restated Certificate
of Incorporation of the Company filed herewith as Exhibit 3.1; Article VI of the
Bylaws of the Company, filed herewith as Exhibit 3.2; Section 145 of the
Delaware General Corporation Law; and the form of indemnification agreement
filed herewith as Exhibit 10.14 which, among other things, and subject to
certain conditions, authorize the Company to indemnify, or indemnify by their
terms, as the case may be, the directors and officers of the Company against
certain liabilities and expenses incurred by such persons in connection with
claims made by reason of their being such a director or officer.
 
    Section 10 of the form of the Underwriting Agreement filed as Exhibit 1.1 to
this Registration Statement provides for indemnification by the Underwriters and
their controlling persons, on the one hand, and of the Company and its
controlling persons on the other hand, for certain liabilities arising under the
Securities Act of 1933, as amended (the "Act"), the Exchange Act of 1934, as
amended, or otherwise.
 
    The Company has obtained directors and officers insurance providing
indemnification for certain of the Company's directors, officers, affiliates,
partners or employees for certain liabilities.
 
ITEM 15. RECENT SALES OF UNREGISTERED SECURITIES
 
    The following information does not give effect to (i) the one-for-two
automatic conversion of the Company's Preferred Stock into the Company's Common
Stock in connection with the Company's initial public offering or (ii) the
three-for-two split of the Company's Common Stock effected in the form of a
stock dividend payable to holders of record as of July 31, 1998.
 
    (a) In February 1998, the Company issued 8,106 shares of its Series E
Preferred Stock pursuant to the net exercise of a warrant by Silicon Valley Bank
at an exercise price of $7.94 per share.
 
    (b) In October 1995, the Company issued warrants to purchase 34,630 shares
of Series E Preferred Stock of the Company at an exercise price of $7.94 per
share to 9 stockholders under a loan agreement whereby the Company issued
promissory notes to such stockholders with an aggregate principal amount of
 
                                      II-1
<PAGE>
$1,100,000. In December 1995, the Company issued warrants to purchase 91,296
shares of Series E Preferred Stock of the Company at an exercise price of $7.94
per share to an additional 37 stockholders under a separate loan agreement
whereby the Company issued promissory notes to such stockholders with an
aggregate principal amount of $2,900,000. In September and October 1997, the
stockholders exercised the warrants, a portion of which were exercised pursuant
to net exercise provisions, to purchase 122,430 shares of Series E Preferred
Stock for aggregate cash proceeds of $923,000.
 
    (c) In April 1996, the Company issued a warrant to purchase 9,500 shares of
its Series E Preferred Stock at an exercise price of $7.94 per share to Coast
Business Credit ("Coast") in connection with a line of credit.
 
    (d) In May 1996, in connection with its acquisition of Dimension Solutions,
Inc. ("Dimension Solutions") the Company issued 40,000 shares of Series E
Preferred Stock to Dimension Solutions.
 
    (e) In July 1996, the Company issued a warrant to purchase 10,000 shares of
its Series E Preferred Stock at an exercise price of $7.94 per share to LINC
Capital Management in connection with an equipment lease. In November 1997, LINC
Capital Management purchased 8,040 shares of Series E Preferred Stock, a portion
of which was exercised under a net exercise provision, for aggregate cash
proceeds of $36,000.
 
    (f) In October 1996, the Company issued a warrant to purchase 9,500 shares
of its Common Stock at an exercise price of 7.94 per share to Coast in
connection with an amendment to the line of credit.
 
    (g) In November 1996, the Company issued a warrant to purchase 22,500 shares
of its Common Stock at an exercise price of $7.94 per share to Britannia
Hacienda V Limited Partnership and its partners in connection with a facilities
lease.
 
    (h) In January 1997, the Company issued warrants to purchase an aggregate of
50,000 shares of its Common Stock at an exercise price of $9.00 per share to two
of the former shareholders of BeneSphere in connection with the Company's
acquisition of BeneSphere.
 
    (i) In March 1997, the Company issued 574,733 shares of Series F Preferred
Stock to two affiliates of GAP LLC at $17.40 per share for an aggregate purchase
price of $10,000,354.
 
    (j) In July 1997, the Company issued a warrant to purchase 20,000 shares of
its Common Stock to a client of the Company at an exercise price of $9.00 per
share.
 
    (k) Since 1989 and through June 30, 1998, the Company has granted stock
options to purchase 4,894,788 shares of the Company's Common Stock at a weighted
average exercise price of $3.30 per share to employees, consultants and
directors pursuant to its 1996 Stock Option Plan, or predecessor plans. Of these
options, 555,272 have been canceled without being exercised, 2,539,100 have been
exercised and 1,800,416 remain outstanding.
 
    The sales and issuances of securities described in paragraphs (a) through
(j) were deemed to be exempt from registration under the Securities Act by
virtue of Section 4(2) of the Securities Act as transactions by an issuer not
involving a public offering. The sales and issuances of securities described in
paragraph (k) were deemed to be exempt from registration from the Securities Act
by virtue of either Rule 701 of the Securities Act as they were offered and sold
pursuant to written compensatory benefit plans as provided by Rule 701 or
Section 4(2) of the Securities Act as transaction by an issuer not involving a
public offering.
 
                                      II-2
<PAGE>
ITEM 16. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES
 
    (A) EXHIBITS
 
<TABLE>
<CAPTION>
  EXHIBIT      EXHIBIT
 FOOTNOTE      NUMBER     DESCRIPTION
- -----------  -----------  -------------------------------------------------------------------------------------------
<C>          <C>          <S>
                    1.1   Form of Underwriting Agreement.
    (1)             2.1   Agreement and Plan of Reorganization, dated May 23, 1996, between Registrant and Dimension
                           Solutions.
    (1)             2.2   Stock Acquisition Agreement, dated January 1, 1997, between Registrant and BeneSphere
                           Administrators, Inc.
    (2)             3.1   Amended and Restated Certificate of Incorporation.
    (1)             3.2   Bylaws of the Registrant.
    (1)             4.1   Specimen Common Stock Certificate of Registrant.
    (1)             4.2   Amended and Restated Registration Rights Agreement, dated March 12, 1997 between
                           Registrant, General Atlantic Partners 39, L.P., GAP Coinvestment Partners, L.P. and
                           certain stockholders of Registrant.
    (1)             4.3   Warrant to Purchase Stock, dated January 13, 1995, between Registrant and Silicon Valley
                           Bank and related Antidilution and Registration Rights Agreements.
    (1)             4.4(a) Warrant to Purchase Stock, dated April 30, 1996, between Registrant and Coast Business
                           Credit and related Antidilution and Registration Rights Agreement.
    (1)             4.4(b) Warrant to Purchase Stock, dated October 25, 1996, between Registrant and Coast Business
                           Credit and related Antidilution and Registration Rights Agreement.
    (1)             4.5   Warrant to Purchase Series E Preferred Stock, dated July 31, 1996, between Registrant and
                           LINC Capital Management.
    (1)             4.6(a) Warrant Purchase Agreement, dated November 14, 1996, between Registrant and certain
                           purchasers.
    (1)             4.6(b) Warrant to Purchase Series E Preferred Stock, dated November 14, 1996, between Registrant
                           and T.J. Bristow and Elizabeth S. Bristow.
    (1)             4.6(c) Warrant to Purchase Series E Preferred Stock, dated November 14, 1996, between Registrant
                           and SDK Incorporated.
    (1)             4.6(d) Warrant to Purchase Series E Preferred Stock, dated November 14, 1996, between Registrant
                           and Laurence Shushan and Magdalena Shushan.
    (1)             4.7(a) Warrant to Purchase Common Stock, dated January 7, 1997, between Registrant and Louis R.
                           Baransky.
    (1)             4.7(b) Warrant to Purchase Common Stock, dated January 7, 1997, between Registrant and Ben W.
                           Reppond.
    (1)             4.8   Form of Note issued by Registrant on October 20, 1995 and December 12, 1995 (see also
                           Exhibit 10.12).
                    5.1*  Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation.
    (1)            10.1   Lease Agreement, dated August 12, 1992, First Amendment to Lease, dated March 23, 1994,
                           Second Amendment to Lease dated December 9, 1994, and Third Amendment to Lease, dated
                           March 16, 1995 between Registrant and Hacienda Park Associates.
                   10.2*  Sublease, dated April 14, 1998, between the Registrant and Documentum, Inc.
    (1)            10.3   Lease Agreement and Addendum Number One, dated August 26, 1993, and First Amendment to
                           Lease, dated March 23, 1994, between Registrant and Hacienda Park Associates.
</TABLE>
 
                                      II-3
<PAGE>
<TABLE>
<CAPTION>
  EXHIBIT      EXHIBIT
 FOOTNOTE      NUMBER     DESCRIPTION
- -----------  -----------  -------------------------------------------------------------------------------------------
<C>          <C>          <S>
    (1)            10.4   Lease Agreement, dated March 23, 1994, First Amendment, dated May 25, 1994 and Second
                           Amendment, dated October 5, 1994 between Registrant and Hacienda Park Associates.
    (1)            10.5   Lease Agreement, dated November 13, 1995, and First Amendment to Lease, dated February 23,
                           1996, between Registrant and Hacienda Park Associates.
    (1)            10.6*  Built-to-Suit Lease, dated September 27, 1996, and First Amendment, dated January 27, 1998,
                           between Registrant and Britannia Hacienda V Limited Partnership.
    (1)            10.7   Office Lease, dated March 22, 1996, between Benefits-Plus Administrators, Inc. and the
                           Trustees under the Will and of the Estate of James Campbell, Deceased and related Guaranty
                           of Lease.
                   10.8*  Sublease, dated October 10, 1997, between Registrant and Drake Mortgage Corporation.
                   10.9*  Build-to-Suit lease, dated January 27, 1998, between Registrant and Britannia Hacienda V
                           Limited Partnership.
    (1)           10.10   1996 Stock Option Plan and related Form of Stock Option Agreement.
    (1)           10.11   1996 Employee Stock Purchase Plan.
    (1)           10.12   Employment and Non-competition Agreement, dated May 23, 1996 between Registrant and Dwight
                           L. Jackson.
    (1)           10.13   Equipment Lease and Addendum No. 1, dated July 31, 1996, between Registrant and LINC
                           Capital Management and related Equipment Schedule.
    (1)           10.14   Form of Indemnification Agreement between Registrant and executive officers and directors.
    (1)           10.15   Loan Agreement, dated October 20, 1995 between Registrant and certain investors, and First
                           Amendment to Loan Agreement, dated December 12, 1995, between Registrant and certain
                           investors.
    (1)           10.16*  Amended and Restated Loan and Security Agreement, dated April 30, 1998, between Registrant
                           and Coast Business Credit.
    (1)           10.17   Promissory Note, dated December 5, 1996, between Registrant and Robert Schneider.
    (1)           10.18   Promissory Note, dated January 7, 1997, between Registrant and Alison Elder.
    (1)           10.19   Promissory Note, dated January 31, 1997, between Registrant and Jeffrey Bizzack.
    (1)           10.20   Office Building Lease between Koll Center Irvine Number Two and Registrant dated November
                           7, 1994, and Amendments Nos. 1 and 2, thereto.
    (1)           10.21   Lease (Full Service Office Lease), as amended by and between Callahan Pentz Properties and
                           Registrant, assigned to Registrant on February 29, 1996.
    (1)           10.22   Promissory Note, dated December 31, 1996 between BeneSphere Administrators, Inc. and Alison
                           Elder.
    (1)           10.23   Series F Stock Purchase Agreement dated March 12, 1997, between Registrant, General
                           Atlantic Partners 39, L.P. and GAP Coinvestment Partners, L.P.
    (1)           10.24   Stockholders Agreement dated March 12, 1997 between Registrant, General Atlantic Partners
                           39, L.P., GAP Coinvestment Partners, L.P. and Sinton (as defined therein).
    (1)           10.25   Standard Office Lease -- Gross, dated March 27, 1997 between Registrant and Westwood
                           Holdings, Inc.
    (1)           10.26   ISDA Master Agreement dated June 10, 1997 between Registrant and First Union National Bank.
                   23.1   Consent of Ernst & Young LLP, Independent Auditors.
                   23.2*  Consent of Wilson Sonsini Goodrich & Rosati, P.C. (included in Exhibit 5.1).
</TABLE>
 
                                      II-4
<PAGE>
<TABLE>
<CAPTION>
  EXHIBIT      EXHIBIT
 FOOTNOTE      NUMBER     DESCRIPTION
- -----------  -----------  -------------------------------------------------------------------------------------------
<C>          <C>          <S>
                   24.1   Powers of attorney (See page II-6)
                   27.1   Financial Data Schedule.
</TABLE>
 
- ------------------------
 
*   To be filed by amendment.
 
(1) Incorporated by reference to the Registrant's Registration Statement on Form
    S-1, as amended (File No. 333-23189), declared effective on September 18,
    1997.
 
(2) Incorporated by reference from the Registrant's Registration Statement on
    Form S-8 (File No. 333-37129) filed with the Securities and Exchange
    Commission on October 3, 1998.
 
    (b) Financial Statement Schedules
 
    Schedule II Valuation Allowance Schedule
 
ITEM 17.  UNDERTAKINGS
 
    The undersigned Registrant hereby undertakes to provide to the Underwriters
at the closing specified in the Underwriting Agreement certificates in such
denominations and registered in such names as required by the Underwriters to
permit prompt delivery to each purchaser.
 
    Insofar as indemnification for liabilities arising under the Securities Act
of 1933 may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Securities and Exchange Commission
such indemnification is against public policy as expressed in the Act and is,
therefore, unenforceable. In the event that a claim for indemnification against
such liabilities (other than the payment by the Registrant of expenses incurred
or paid by a director, officer or controlling person of the Registrant in the
successful defense of any action, suit or proceeding) is asserted by such
director, officer or controlling person in connection with the securities being
registered, the Registrant will, unless in the opinion of its counsel the matter
has been settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Act and will be governed by the final adjudication of
such issue.
 
    The undersigned Registrant hereby undertakes that:
 
    (1) For purposes of determining any liability under the Securities Act of
1933, the information omitted from the form of prospectus filed as part of this
Registration Statement in reliance upon Rule 430A and contained in a form of
prospectus filed by the Registrant pursuant to Rule 424(b)(1) or (4) or 497(h)
under the Securities Act shall be deemed to be part of this Registration
Statement as of the time it was declared effective.
 
    (2) For the purpose of determining any liability under the Securities Act of
1933, each post-effective amendment that contains a form of prospectus shall be
deemed to be a new registration statement relating to the securities offered
therein, and the offering of such securities at that time shall be deemed to be
the initial bona fide offering thereof.
 
                                      II-5
<PAGE>
                                   SIGNATURES
 
    Pursuant to the requirements of the Securities Act of 1933, the Registrant
has duly caused this Registration Statement to be signed on its behalf by the
undersigned, thereunto duly authorized, in the City of Pleasanton, State of
California, on this 5th day of August, 1998.
 
<TABLE>
<S>                             <C>  <C>
                                PROBUSINESS SERVICES, INC.
 
                                By:             /s/ THOMAS H. SINTON
                                     -----------------------------------------
                                                  Thomas H. Sinton
                                       PRESIDENT AND CHIEF EXECUTIVE OFFICER
</TABLE>
 
                               POWER OF ATTORNEY
 
    KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears
below constitutes and appoints Thomas H. Sinton and Steven E. Klei, and each of
them singly, as true and lawful attorneys-in-fact and agents with full power of
substitution and resubstitution, for him and in his name, place and stead, in
any and all capacities to sign the Registration Statement filed herewith and any
or all amendments to said Registration Statement (including post-effective
amendments and registration statements filed pursuant to Rule 462 and
otherwise), and to file the same, with all exhibits thereto and other documents
in connection therewith, with the Securities and Exchange Commission or any
regulatory authority granting unto said attorneys-in-fact and agents the full
power and authority to do and perform each and every act and thing requisite and
necessary to be done in and about the foregoing, as fully to all intents and
purposes as he might or could do in person, hereby ratifying and confirming all
that said attorneys-in-fact and agents or any of them, or their or his
substitute, may lawfully do or cause to be done by virtue hereof.
 
    Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed by the following persons in the
capacities and on the dates indicated:
 
<TABLE>
<CAPTION>
                      SIGNATURE                                         TITLE                         DATE
- ------------------------------------------------------  --------------------------------------  -----------------
 
<C>                                                     <S>                                     <C>
                 /s/ THOMAS H. SINTON                   President, Chief Executive Officer and
     -------------------------------------------         Director (Principal Executive           August 5, 1998
                   Thomas H. Sinton                      Officer)
 
                                                        Senior Vice President, Finance, Chief
                  /s/ STEVEN E. KLEI                     Financial Officer and Secretary
     -------------------------------------------         (Principal Financial and Accounting     August 5, 1998
                    Steven E. Klei                       Officer)
 
               /s/ WILLIAM T. CLIFFORD
     -------------------------------------------        Director                                 August 5, 1998
                 William T. Clifford
 
                 /s/ DAVID C. HODGSON
     -------------------------------------------        Director                                 August 5, 1998
                   David C. Hodgson
 
                /s/ RONALD W. READMOND
     -------------------------------------------        Director                                 August 5, 1998
                  Ronald W. Readmond
 
                 /s/ THOMAS P. RODDY
     -------------------------------------------        Director                                 August 5, 1998
                   Thomas P. Roddy
</TABLE>
 
                                      II-6
<PAGE>
                                                                     SCHEDULE II
 
                               PROBUSINESS, INC.
                             (DOLLARS IN THOUSANDS)
 
VALUATION ALLOWANCE
 
<TABLE>
<CAPTION>
                                                                                             YEAR ENDED JUNE 30,
                                                                                       -------------------------------
                                                                                         1996       1997       1998
                                                                                       ---------  ---------  ---------
<S>                                                                                    <C>        <C>        <C>
DEFERRED TAX ASSETS
Balance at beginning of year.........................................................  $   2,988  $   3,597  $   5,988
Additions............................................................................        609      2,391      3,236
Reductions...........................................................................     --         --         --
Balance at end of year...............................................................  $   3,597  $   5,988  $   9,224
</TABLE>
 
<TABLE>
<CAPTION>
                                                                                             YEAR ENDED JUNE 30,
                                                                                       -------------------------------
                                                                                         1996       1997       1998
                                                                                       ---------  ---------  ---------
<S>                                                                                    <C>        <C>        <C>
ALLOWANCE FOR DOUBTFUL ACCOUNTS
Balance at beginning of year.........................................................  $  --      $  --      $     365
Additions............................................................................     --            365         84
Reductions...........................................................................     --         --             29
Balance at end of year...............................................................  $  --      $     365  $     420
</TABLE>
 
                                      S-1
<PAGE>
                                 EXHIBIT INDEX
 
<TABLE>
<CAPTION>
  EXHIBIT      EXHIBIT
 FOOTNOTE      NUMBER     DESCRIPTION
- -----------  -----------  -------------------------------------------------------------------------------------------
<C>          <C>          <S>
                    1.1   Form of Underwriting Agreement.
    (1)             2.1   Agreement and Plan of Reorganization, dated May 23, 1996, between Registrant and Dimension
                           Solutions.
    (1)             2.2   Stock Acquisition Agreement, dated January 1, 1997, between Registrant and BeneSphere
                           Administrators, Inc.
    (2)             3.1   Amended and Restated Certificate of Incorporation.
    (1)             3.2   Bylaws of the Registrant.
    (1)             4.1   Specimen Common Stock Certificate of Registrant.
    (1)             4.2   Amended and Restated Registration Rights Agreement, dated March 12, 1997 between
                           Registrant, General Atlantic Partners 39, L.P., GAP Coinvestment Partners, L.P. and
                           certain stockholders of Registrant.
    (1)             4.3   Warrant to Purchase Stock, dated January 13, 1995, between Registrant and Silicon Valley
                           Bank and related Antidilution and Registration Rights Agreements.
    (1)             4.4(a) Warrant to Purchase Stock, dated April 30, 1996, between Registrant and Coast Business
                           Credit and related Antidilution and Registration Rights Agreement.
    (1)             4.4(b) Warrant to Purchase Stock, dated October 25, 1996, between Registrant and Coast Business
                           Credit and related Antidilution and Registration Rights Agreement.
    (1)             4.5   Warrant to Purchase Series E Preferred Stock, dated July 31, 1996, between Registrant and
                           LINC Capital Management.
    (1)             4.6(a) Warrant Purchase Agreement, dated November 14, 1996, between Registrant and certain
                           purchasers.
    (1)             4.6(b) Warrant to Purchase Series E Preferred Stock, dated November 14, 1996, between Registrant
                           and T.J. Bristow and Elizabeth S. Bristow.
    (1)             4.6(c) Warrant to Purchase Series E Preferred Stock, dated November 14, 1996, between Registrant
                           and SDK Incorporated.
    (1)             4.6(d) Warrant to Purchase Series E Preferred Stock, dated November 14, 1996, between Registrant
                           and Laurence Shushan and Magdalena Shushan.
    (1)             4.7(a) Warrant to Purchase Common Stock, dated January 7, 1997, between Registrant and Louis R.
                           Baransky.
    (1)             4.7(b) Warrant to Purchase Common Stock, dated January 7, 1997, between Registrant and Ben W.
                           Reppond.
    (1)             4.8   Form of Note issued by Registrant on October 20, 1995 and December 12, 1995 (see also
                           Exhibit 10.12).
                    5.1*  Opinion of Wilson Sonsini Goodrich & Rosati, Professional Corporation.
    (1)            10.1   Lease Agreement, dated August 12, 1992, First Amendment to Lease, dated March 23, 1994,
                           Second Amendment to Lease dated December 9, 1994, and Third Amendment to Lease, dated
                           March 16, 1995 between Registrant and Hacienda Park Associates.
                   10.2*  Sublease, dated April 14, 1998, between the Registrant and Documentum, Inc.
    (1)            10.3   Lease Agreement and Addendum Number One, dated August 26, 1993, and First Amendment to
                           Lease, dated March 23, 1994, between Registrant and Hacienda Park Associates.
    (1)            10.4   Lease Agreement, dated March 23, 1994, First Amendment, dated May 25, 1994 and Second
                           Amendment, dated October 5, 1994 between Registrant and Hacienda Park Associates.
    (1)            10.5   Lease Agreement, dated November 13, 1995, and First Amendment to Lease, dated February 23,
                           1996, between Registrant and Hacienda Park Associates.
</TABLE>
<PAGE>
<TABLE>
<CAPTION>
  EXHIBIT      EXHIBIT
 FOOTNOTE      NUMBER     DESCRIPTION
- -----------  -----------  -------------------------------------------------------------------------------------------
<C>          <C>          <S>
    (1)            10.6*  Built-to-Suit Lease, dated September 27, 1996, and First Amendment, dated January 27, 1998,
                           between Registrant and Britannia Hacienda V Limited Partnership.
    (1)            10.7   Office Lease, dated March 22, 1996, between Benefits-Plus Administrators, Inc. and the
                           Trustees under the Will and of the Estate of James Campbell, Deceased and related Guaranty
                           of Lease.
                   10.8*  Sublease, dated October 10, 1997, between Registrant and Drake Mortgage Corporation.
                   10.9*  Build-to-Suit lease, dated January 27, 1998, between Registrant and Britannia Hacienda V
                           Limited Partnership.
    (1)           10.10   1996 Stock Option Plan and related Form of Stock Option Agreement.
    (1)           10.11   1996 Employee Stock Purchase Plan.
    (1)           10.12   Employment and Non-competition Agreement, dated May 23, 1996 between Registrant and Dwight
                           L. Jackson.
    (1)           10.13   Equipment Lease and Addendum No. 1, dated July 31, 1996, between Registrant and LINC
                           Capital Management and related Equipment Schedule.
    (1)           10.14   Form of Indemnification Agreement between Registrant and executive officers and directors.
    (1)           10.15   Loan Agreement, dated October 20, 1995 between Registrant and certain investors, and First
                           Amendment to Loan Agreement, dated December 12, 1995, between Registrant and certain
                           investors.
    (1)           10.16*  Amended and Restated Loan and Security Agreement, dated April 30, 1998, between Registrant
                           and Coast Business Credit.
    (1)           10.17   Promissory Note, dated December 5, 1996, between Registrant and Robert Schneider.
    (1)           10.18   Promissory Note, dated January 7, 1997, between Registrant and Alison Elder.
    (1)           10.19   Promissory Note, dated January 31, 1997, between Registrant and Jeffrey Bizzack.
    (1)           10.20   Office Building Lease between Koll Center Irvine Number Two and Registrant dated November
                           7, 1994, and Amendments Nos. 1 and 2, thereto.
    (1)           10.21   Lease (Full Service Office Lease), as amended by and between Callahan Pentz Properties and
                           Registrant, assigned to Registrant on February 29, 1996.
    (1)           10.22   Promissory Note, dated December 31, 1996 between BeneSphere Administrators, Inc. and Alison
                           Elder.
    (1)           10.23   Series F Stock Purchase Agreement dated March 12, 1997, between Registrant, General
                           Atlantic Partners 39, L.P. and GAP Coinvestment Partners, L.P.
    (1)           10.24   Stockholders Agreement dated March 12, 1997 between Registrant, General Atlantic Partners
                           39, L.P., GAP Coinvestment Partners, L.P. and Sinton (as defined therein).
    (1)           10.25   Standard Office Lease -- Gross, dated March 27, 1997 between Registrant and Westwood
                           Holdings, Inc.
    (1)           10.26   ISDA Master Agreement dated June 10, 1997 between Registrant and First Union National Bank.
                   23.1   Consent of Ernst & Young LLP, Independent Auditors.
                   23.2*  Consent of Wilson Sonsini Goodrich & Rosati, P.C. (included in Exhibit 5.1).
                   24.1   Powers of attorney (See page II-6)
                   27.1   Financial Data Schedule.
</TABLE>
 
- ------------------------
 
*   To be filed by amendment.
 
(1) Incorporated by reference to the Registrant's Registration Statement on Form
    S-1, as amended (File No. 333-23189), declared effective on September 18,
    1997.
<PAGE>
(2) Incorporated by reference from the Registrant's Registration Statement on
    Form S-8 (File No. 333-37129) filed with the Securities and Exchange
    Commission on October 3, 1998.

<PAGE>

                                                                  Exhibit 1.1
 
                              ProBusiness Services, Inc.

                            _____ Shares Common Stock (1)

                                UNDERWRITING AGREEMENT

                                                           ______________, 1998

William Blair & Company, L.L.C.
BancAmerica Robertson Stephens
SG Cowen Securities Corporation
     As Representatives of the Several
     Underwriters Named in Schedule A
c/o William Blair & Company, L.L.C.
222 West Adams Street
Chicago, Illinois  60606

Ladies and Gentlemen:

     SECTION 1.     INTRODUCTORY.  ProBusiness Services, Inc. ("COMPANY") a
Delaware corporation, has an authorized capital stock consisting of 5,000,000
shares of Preferred Stock, $0.001 par value, none of which were outstanding as
of June 30, 1998 and 60,000,000 shares, $0.001 par value, of Common Stock
("COMMON STOCK"), of which ________ shares were outstanding as of such date. 
The Company proposes to issue and sell ________ shares of its authorized but
unissued Common Stock ("FIRM SHARES") to the several underwriters named in
Schedule A as it may be amended by the Pricing Agreement hereinafter defined
("UNDERWRITERS"), who are acting severally and not jointly.  In addition, the
Company proposes to grant to the Underwriters an option to purchase up to
__________ additional shares of Common Stock ("OPTION SHARES") as provided in
Section 4 hereof.  The Firm Shares and, to the extent such option is exercised,
the Option Shares, are hereinafter collectively referred to as the "SHARES."

     You have advised the Company that the Underwriters propose to make a public
offering of their respective portions of the Shares as soon as you deem
advisable after the registration statement hereinafter referred to becomes
effective, if it has not yet become effective, and the Pricing Agreement
hereinafter defined has been executed and delivered.


- ----------------------
(1) Plus an option to acquire up to _____ additional shares to cover
    overallotments.

<PAGE>

     Prior to the purchase and public offering of the Shares by the several
Underwriters, the Company and the Representatives, acting on behalf of the
several Underwriters, shall enter into an agreement substantially in the form of
Exhibit A hereto (the "PRICING AGREEMENT").  The Pricing Agreement may take the
form of an exchange of any standard form of written telecommunication between
the Company and the Representatives and shall specify such applicable
information as is indicated in Exhibit A hereto.  The offering of the Shares
will be governed by this Agreement, as supplemented by the Pricing Agreement. 
From and after the date of the execution and delivery of the Pricing Agreement,
this Agreement shall be deemed to incorporate the Pricing Agreement.

     The Company hereby confirms its agreement with the Underwriters as follows:

     SECTION 2.     REPRESENTATIONS AND WARRANTIES OF THE COMPANY.  The Company
represents and warrants to the several Underwriters that:

          (a)  A registration statement on Form S-1 (File No. 333-_____) and a
     related preliminary prospectus with respect to the Shares have been
     prepared and filed with the Securities and Exchange Commission
     ("COMMISSION") by the Company in conformity with the requirements of the
     Securities Act of 1933, as amended, and the rules and regulations of the
     Commission thereunder (collectively, the "1933 ACT;" all references herein
     to specific rules are rules promulgated under the 1933 Act); and the
     Company has so prepared and has filed such amendments thereto, if any, and
     such amended preliminary prospectuses as may have been required to the date
     hereof.  If the Company has elected not to rely upon Rule 430A, the Company
     has prepared and will promptly file an amendment to the registration
     statement and an amended prospectus.  If the Company has elected to rely
     upon Rule 430A, it will prepare and file a prospectus pursuant to Rule
     424(b) that discloses the information previously omitted from the
     prospectus in reliance upon Rule 430A.  There have been or will promptly be
     delivered to you three signed copies of such registration statement and
     amendments, three copies of each exhibit filed therewith, and conformed
     copies of such registration statement and amendments (but without exhibits)
     and of the related preliminary prospectus or prospectuses and final forms
     of prospectus for each of the Underwriters.

               Such registration statement (as amended, if applicable) at the
     time it becomes effective and the prospectus constituting a part thereof
     (including the information, if any, deemed to be part thereof pursuant to
     Rule 430A(b) and/or Rule 434), as from time to time amended or
     supplemented, are hereinafter referred to as the "REGISTRATION STATEMENT,"
     and the "PROSPECTUS," respectively, except that if any revised prospectus
     shall be provided to the Underwriters by the Company for use in connection
     with the offering of the Shares which differs from the Prospectus on file
     at the Commission at the time the Registration Statement became or becomes
     effective (whether or not such revised prospectus is required to be filed
     by the Company pursuant to Rule 424(b)), the term Prospectus shall refer to
     such revised prospectus from and after the time it was provided to the
     Underwriters for such use.  If the Company elects to rely on Rule 434 of
     the 1933 Act, all references 

                                    -2-
<PAGE>

     to "Prospectus" shall be deemed to include, without limitation, the form 
     of prospectus and the term sheet, taken together, provided to the 
     Underwriters by the Company in accordance with Rule 434 of the 1933 Act 
     ("RULE 434 PROSPECTUS").  Any registration statement (including any 
     amendment or supplement thereto or information which is deemed part 
     thereof) filed by the Company under Rule 462(b) ("RULE 462(b) 
     REGISTRATION STATEMENT") shall be deemed to be part of the "Registration 
     Statement" as defined herein, and any prospectus (including any amendment 
     or supplement thereto or information which is deemed part thereof) 
     included in such registration statement shall be deemed to be part of the 
     "Prospectus", as defined herein, as appropriate.  The Securities Exchange 
     Act of 1934, as amended, and the rules and regulations of the Commission 
     thereunder are hereinafter collectively referred to as the "EXCHANGE ACT". 

          (b)  The Commission has not issued any order preventing or suspending
     the use of any preliminary prospectus or instituted proceedings for that
     purpose, and each preliminary prospectus has conformed in all material
     respects with the requirements of the 1933 Act and, as of its date, has not
     included any untrue statement of a material fact or omitted to state a
     material fact necessary to make the statements therein, in light of the
     circumstances under which they were made, not misleading; and when the
     Registration Statement became or becomes effective, and at all times
     subsequent thereto, up to the First Closing Date and the Second Closing
     Date hereinafter defined, as the case may be, the Registration Statement,
     including the information deemed to be part of the Registration Statement
     at the time of effectiveness pursuant to Rule 430A(b), if applicable, and
     the Prospectus and any amendments or supplements thereto, contained and
     will contain all material information that is required to be stated therein
     in accordance with the 1933 Act and in all material respects conformed or
     will in all material respects conform to the requirements of the 1933 Act,
     and neither the Registration Statement nor the Prospectus, nor any
     amendment or supplement thereto, included or will include any untrue
     statement of a material fact or omitted or will omit to state a material
     fact required to be stated therein or necessary to make the statements
     therein not misleading; PROVIDED, HOWEVER, that the Company makes no
     representation or warranty as to information contained in or omitted from
     any preliminary prospectus, the Registration Statement, the Prospectus or
     any such amendment or supplement in reliance upon and in conformity with
     written information furnished to the Company by or on behalf of any
     Underwriter through the Representatives specifically for use in the
     preparation thereof.

          (c)  The Company and its subsidiaries have been duly incorporated and
     are validly existing as corporations in good standing under the laws of
     their respective places of incorporation, with corporate and other power
     and authority to own, lease and operate their properties and conduct their
     business as described in the Prospectus; the Company and each of its
     subsidiaries are duly qualified to do business as foreign corporations
     under the corporation law of, and are in good standing as such in, each
     jurisdiction in which they own or lease substantial properties, have an
     office, or in which substantial business is conducted and such
     qualification is required except in any such case where the failure to so
     qualify or be in good standing would not have a material adverse effect
     upon 

                                    -3-
<PAGE>



     the Company and its subsidiaries taken as a whole; no proceeding of
     which the Company has knowledge has been instituted in any such
     jurisdiction, revoking, limiting or curtailing, or seeking to revoke, limit
     or curtail, such power and authority or qualification; and each of the
     Company and its subsidiaries is in possession of and operating in
     compliance with all authorizations, licenses, certificates, consents,
     orders and permits from state, federal and other regulatory authorities
     which are material to the conduct of its business, all of which are valid
     and in full force and effect.

          (d)  Except as disclosed in the Registration Statement, the Company
     owns directly or indirectly 100 percent of the issued and outstanding
     capital stock of each of its subsidiaries, free and clear of any claims,
     liens, pledges, encumbrances or security interests and all of such capital
     stock has been duly authorized and validly issued and is fully paid and
     nonassessable.

          (e)  The issued and outstanding shares of capital stock of the Company
     as set forth in the Prospectus have been duly authorized and validly
     issued, are fully paid and nonassessable, and conform to the description
     thereof contained in the Prospectus.

          (f)  The Shares have been duly authorized and when issued, delivered
     and paid for pursuant to this Agreement, will be validly issued, fully paid
     and nonassessable, and will conform to the description thereof contained in
     the Prospectus.

          (g)  The making and performance by the Company of this Agreement and
     the Pricing Agreement have been duly authorized by all necessary corporate
     action and will not violate any provision of the Company's charter or
     bylaws and will not result in a breach of, or be in contravention of,  or
     constitute a default under (i) any provision of any material agreement,
     franchise, license, indenture, mortgage, deed of trust, or other instrument
     to which the Company or any subsidiary is a party or by which the Company,
     any subsidiary or the property of any of them may be bound or affected, or
     (ii) any material order, rule or regulation applicable to the Company or
     any subsidiary of any court or regulatory body, administrative agency or
     other governmental body having jurisdiction over the Company or any
     subsidiary or any of their respective properties, or any order of any court
     or governmental agency or authority entered in any proceeding to which the
     Company or any subsidiary was or is now a party or by which it is bound. 
     No consent, approval, authorization or other order of any court, regulatory
     body, administrative agency or other governmental body, domestic or
     foreign, is required for the execution and delivery of this Agreement or
     the Pricing Agreement or the consummation of the transactions contemplated
     herein or therein, except for compliance with the 1933 Act or the Exchange
     Act, or blue sky laws applicable to the public offering of the Shares by
     the several Underwriters, which requirements will have been satisfied prior
     to the Closing Date (as defined herein) in all material respects, and
     clearance of such offering with the National Association of Securities
     Dealers, Inc. ("NASD").  This Agreement has been duly executed and
     delivered by the Company.

                                    -4-
<PAGE>


          (h)  The accountants who have expressed their opinions with respect to
     certain of the financial statements and schedules included in the
     Registration Statement are independent accountants as required by the 1933
     Act.

          (i)  The consolidated financial statements and schedules of the
     Company included in the Registration Statement as filed with the Commission
     present fairly the consolidated financial position of the Company and its
     subsidiaries as of the respective dates of such financial statements, and
     the consolidated results of operations and cash flows of the Company for
     the respective periods covered thereby, all in conformity with generally
     accepted accounting principles consistently applied throughout the periods
     involved, except as disclosed in the Prospectus; and the supporting
     schedules included in the Registration Statement present fairly the
     information required to be stated therein.  The financial information set
     forth in the Prospectus under "Selected Consolidated Financial Data"
     presents fairly on a basis consistent with the audited financial statements
     presented in the Prospectus, the information set forth therein.  No other
     statements or schedules are required to be included in the Registration
     Statement.  The pro forma financial statements and other pro forma
     information included in the Prospectus present fairly the information shown
     therein, have been prepared in accordance with generally accepted
     accounting principles and the Commission's rules and guidelines with
     respect to pro forma financial statements and other pro forma information,
     have been properly compiled on the pro forma basis described therein, and,
     in the opinion of the Company, the assumptions used in the preparation
     thereof are reasonable and the adjustments used therein are appropriate
     under the circumstances.

          (j)  Neither the Company nor any subsidiary is in violation of its
     charter or bylaws or in default under any consent decree, or in default
     with respect to any material provision of any material lease, loan
     agreement, franchise, license, permit or other contract obligation to which
     it is a party; and there does not exist any state of facts which
     constitutes an event of default as defined in such documents or which, with
     notice or lapse of time or both, would constitute such an event of default,
     in each case, except for defaults which neither singly nor in the aggregate
     are material to the Company and its subsidiaries taken as a whole.

          (k)  There are no material legal or governmental proceedings pending,
     or to the best of the Company's knowledge, threatened to which the Company,
     any subsidiary or any of their respective officers is or may be a party or
     of which material property owned or leased, or rights held, by the Company
     or any subsidiary is or may be the subject, or related to environmental or
     discrimination matters which are not disclosed in the Prospectus, or which
     question the validity of this Agreement or the Pricing Agreement or any
     action taken or to be taken pursuant hereto or thereto, or which might
     prevent consummation of the transactions contemplated therein, or which is
     required to be disclosed in the Registration Statement or the prospectus
     and is not so disclosed.

                                    -5-
<PAGE>


          (l)  There are no holders of securities of the Company having rights
     to registration thereof or preemptive rights to purchase Common Stock
     except as disclosed in the Prospectus.  Holders of registration rights have
     waived such rights with respect to the offering being made by the
     Prospectus.

          (m)  Except as set forth in the Registration Statement and the
     Prospectus, the Company and each of its subsidiaries have good and
     marketable title to all the properties and assets reflected as owned in the
     financial statements hereinabove described (or elsewhere in the
     Prospectus), subject to no lien, mortgage, pledge, charge or encumbrance of
     any kind except those, if any, reflected in such financial statements (or
     elsewhere in the Prospectus) or which are not material to the Company and
     its subsidiaries taken as a whole.  The Company and each of its
     subsidiaries hold their respective leased properties which are material to
     the Company and its subsidiaries taken as a whole under valid and
     enforceable leases, except as may be limited by applicable bankruptcy,
     insolvency, reorganization, moratorium or similar laws relating to or
     affecting creditors' rights generally or by general equitable principles. 
     The Company and its subsidiaries own or lease all such properties necessary
     to its operations as described in the Prospectus.

          (n)  The Company has not taken and will not take, directly or
     indirectly, any action designed to or which has constituted or which might
     reasonably be expected to cause or result, under the Exchange Act or
     otherwise, in stabilization or manipulation of the price of any security of
     the Company to facilitate the sale or resale of the Shares.

          (o)  Subsequent to the respective dates as of which information is
     given in the Registration Statement and Prospectus, and except as
     contemplated by the Prospectus, the Company and its subsidiaries, taken as
     a whole, have not incurred any material liabilities or obligations, direct
     or contingent, nor entered into any material transactions not in the
     ordinary course of business and there has not been any material adverse
     change in their condition (financial or otherwise) or results of operations
     nor any material change in their capital stock, short-term debt or 
     long-term debt, nor any dividend or distribution of any kind declared, paid
     or made on the capital stock of the Company or a subsidiary.  There has not
     been any loss or damage (whether or not insured) to the property of the
     Company or any subsidiary which has had a material adverse effect on the
     Company.

          (p)  The Company agrees not to sell, contract to sell or otherwise
     dispose of any Common Stock or securities convertible into Common Stock
     (except Common Stock issued pursuant to currently outstanding options,
     warrants or convertible securities) for a period of 90 days after this
     Agreement becomes effective without the prior written consent of William
     Blair & Company, L.L.C.  Each officer and director of the Company has
     agreed in writing that each such person will not, for a period beginning
     the date of the writing and ending 90 days from the date of the final
     Prospectus (the "LOCK-UP PERIOD"), offer to sell, contract to sell, or
     otherwise sell, dispose of, loan, pledge or grant any rights with respect
     to (collectively, a "DISPOSITION") any shares of Common Stock, any options
     or
                                    -6-
<PAGE>

     warrants to purchase any shares of Common Stock or any securities
     convertible into or exchangeable for shares of Common Stock (collectively,
     "SECURITIES") now owned or hereafter acquired directly by such person or
     with respect to which such person has or hereafter acquires the power of
     disposition, otherwise than (i) if the undersigned is an individual, he or
     she may transfer any Securities either during his or her lifetime or on
     death by will or intestacy to his or her immediate family or to a trust,
     the beneficiaries of which are exclusively the undersigned and/or a member
     or members of his or her immediate family; and (ii) if the undersigned is
     an entity, it may transfer Securities as a distribution to limited partners
     or shareholders of the undersigned, provided, however, that prior to any
     such transfer each transferee shall execute an agreement, satisfactory to
     William Blair & Company, L.L.C., pursuant to which each transferee shall
     agree to receive and hold such Securities subject to the provisions hereof.
     The foregoing restriction has been expressly agreed to preclude the holder
     of the Securities from engaging in any hedging or other transaction which
     is designed to or reasonably expected to lead to or result in a Disposition
     of Securities during the Lock-up Period, even if such Securities would be
     disposed of by someone other than such holder.  Such prohibited hedging or
     other transactions would include, without limitation, any short sale
     (whether or not against the box) or any purchase, sale or grant of any
     right (including, without limitation, any put or call option) with respect
     to any Securities or with respect to any security (other than a broad-based
     market basket or index) that includes, relates to or derives any
     significant part of its value from Securities.  Furthermore, such person
     has also agreed and consented to the entry of stop transfer instructions
     with the Company's transfer agent against the transfer of the Securities
     held by such person except in compliance with this restriction.  The
     Company has provided to counsel for the Underwriters a complete and
     accurate list of all securityholders of the Company and the number and type
     of securities held by each securityholder.  The Company has provided to
     counsel for the Underwriters true, accurate and complete copies of all of
     the agreements pursuant to which its officers, directors and stockholders
     have agreed to such or similar restrictions (the "LOCK-UP AGREEMENTS")
     presently in effect or effected hereby.  The Company hereby represents and
     warrants that it will not release any of its officers, directors or other
     stockholders from any Lock-up Agreements currently existing or hereafter
     effected without the prior written consent of William Blair & Company,
     L.L.C.

          (q)  There is no material document of the Company or its subsidiaries
     of a character required to be described or referred to in the Registration
     Statement or the Prospectus or to be filed as an exhibit to the
     Registration Statement which is not accurately described in all material
     respects or filed as required.

          (r)  The Company together with its subsidiaries owns and possesses all
     right, title and interest in and to, or has duly licensed from third
     parties, all patents, patent rights, trade secrets, inventions, know-how,
     trademarks, trade names, copyrights, service marks and other proprietary
     rights ("TRADE RIGHTS") material to the business of the Company and each of
     its subsidiaries taken as a whole.  Neither the Company nor any of its
     subsidiaries has received any notice of, and neither has knowledge of, any
     infringement, misappropriation or conflict from any third party as to such
     material 

                                    -7-
<PAGE>


     Trade Rights which has not been resolved or disposed of and neither the 
     Company nor any of its subsidiaries has infringed, misappropriated or 
     otherwise conflicted with material Trade Rights of any third parties, 
     which infringement, misappropriation or conflict would have a material 
     adverse effect upon the condition (financial or otherwise), of the Company
     and its subsidiaries taken as a whole.

          (s)  The conduct of the business of the Company and each of its
     subsidiaries is in compliance in all respects with applicable federal,
     state, local and foreign laws and regulations, except where the failure to
     be in compliance would not have a material adverse effect upon the
     condition (financial or otherwise) or results of operations of the Company
     and its subsidiaries taken as a whole.

          (t)  All offers and sales of the Company's capital stock have been
     issued in compliance with all federal and state securities laws, were not
     issued in violation of or subject to any preemptive rights or other rights
     to subscribe for or purchase securities, and the authorized and outstanding
     capital stock of the Company is as set forth in the Prospectus under the
     caption "Capitalization" as of the date stated therein and conforms in all
     material respects to the statements relating thereto contained in the
     Registration Statement and the Prospectus (and such statements correctly
     state the substance of the instruments defining the capitalization of the
     Company in all material respects); the Firm Shares and the Option Shares
     have been duly authorized for issuance and sale to the Underwriters
     pursuant to this Agreement and, when issued and delivered by the Company
     against payment therefor in accordance with the terms of this Agreement,
     will be duly and validly issued and fully paid and nonassessable, and will
     be sold free and clear of any pledge, lien, security interest, encumbrance,
     claim or equitable interest; and no preemptive right, co-sale right,
     registration right, right of first refusal or other similar right of
     stockholders exists with respect to any of the Firm Shares or Option Shares
     or the issuance and sale thereof other than those that have been expressly
     waived prior to the date hereof and those that will automatically expire
     upon and will not apply to the consummation of the transactions
     contemplated on the Closing Date.  No further approval or authorization of
     any stockholder, the Board of Directors of the Company or others is
     required for the issuance and sale or transfer of the Shares except as may
     be required under the 1933 Act or the Exchange Act or under state or other
     securities or blue sky laws.  All issued and outstanding shares of capital
     stock of each subsidiary of the Company have been duly authorized and
     validly issued and are fully paid and nonassessable, and were not issued in
     violation of or subject to any preemptive right or other rights to
     subscribe for or purchase shares and are owned by the Company free and
     clear of any pledge, lien, security interest, encumbrance, claim or
     equitable interest.  Except as disclosed in the Prospectus and the
     financial statements of the Company, and the related notes thereto,
     included in the Prospectus, the Company does not have outstanding any
     options to purchase, or any preemptive rights or other rights to subscribe
     for or to purchase, any securities or obligations convertible into, or any
     contracts or commitments to issue or sell, shares of its capital stock or
     any such options, rights, convertible securities or obligations.  The
     description of the Company's stock option, stock bonus and other stock
     plans or arrangements, and the options or other rights granted and
     exercised thereunder, set forth in the Prospectus accurately and fairly

                                    -8-
<PAGE>

     presents the information required to be shown with respect to such plans,
     arrangements, options and rights.

          (u)  The Company has timely filed all necessary federal and state
     income and franchise tax returns and has paid all taxes shown as due
     thereon, and there is no tax deficiency that has been, or to the best
     knowledge of the Company might be, asserted against the Company or its
     subsidiaries or any of its properties or assets that would or could have a
     material adverse affect upon the condition (financial or otherwise) of the
     Company and its subsidiaries taken as a whole, and all tax liabilities are
     adequately provided for on the books of the Company and its subsidiaries.

          (v)  A registration statement relating to the Common Stock has been
     declared effective by the Commission pursuant to the Exchange Act and the
     Common Stock is duly registered thereunder.  The Shares have been listed on
     the Nasdaq National Market, subject to notice of issuance or sale of the
     Shares, as the case may be.

          (w)  The Company has been advised concerning the Investment Company
     Act of 1940, as amended, and the rules and regulations thereunder (the
     "INVESTMENT COMPANY ACT"), and the Company does not, and does not intend to
     conduct its business in a manner in which it would become, an "investment
     company" of "controlled" by an "investment company" as defined in
     Section 3(a) of the Investment Company Act.

          (x)  The Company confirms as of the date hereof that it is in
     compliance with all provisions of Section 1 of Laws of Florida, 
     Chapter 92-198, AN ACT RELATING TO DISCLOSURE OF DOING BUSINESS WITH CUBA.

          (y)  Neither the Company nor any subsidiary has at any time during the
     past five (5) years (i) made any unlawful contribution to any candidate for
     foreign office or failed to disclose fully any contribution in violation of
     law, or (ii) made any payment to any federal or state governmental officer
     or official, or other person charged with similar public or quasi-public
     duties, other than payments required or permitted by the laws of the United
     States or any jurisdiction thereof.     

          (z)  The Company and each subsidiary maintain insurance with insurers
     of recognized financial responsibility of the types and in the amounts
     generally deemed adequate for their respective business and consistent with
     insurance coverage maintained by similar companies in similar businesses,
     including, but not limited to, insurance covering real and personal
     property owned or leased by the Company or any subsidiary against theft,
     damage, destruction, acts of vandalism and all other risks customarily
     insured against, all of which insurance is in full force and effect;
     neither the Company nor any subsidiary has been refused any insurance
     coverage sought or applied for; and neither the Company nor any subsidiary
     has any reason to believe that it will not be able to renew its existing
     insurance coverage as and when such coverage expires or to obtain similar
     coverage from similar insurers as may 

                                    -9-
<PAGE>

     be necessary to continue its business at a cost that would not materially 
     and adversely affect the condition (financial or otherwise), earnings, 
     operations, business or business prospects of the Company and the 
     subsidiaries considered as one enterprise.

          (aa) To the best of Company's knowledge, no labor disturbance by the
     employees of the Company or any subsidiary exists or is imminent; and the
     Company is not aware of any existing or imminent labor disturbance by the
     employees of any of its principal third-party service providers that might
     be expected to result in a material adverse change in the condition
     (financial or otherwise), earnings, operations, business or business
     prospects of the Company and the subsidiaries considered as one enterprise.
     No collective bargaining agreement exists with any of employees of the
     Company or any subsidiary and, to the best of the Company's knowledge, no
     such agreement is imminent.

          (bb) Each of the Company and its subsidiaries maintains a system of
     internal accounting controls sufficient to provide reasonable assurances
     that (i) transactions are executed in accordance with management's general
     or specific authorizations, (ii) transactions are recorded as necessary to
     permit preparation of financial statements in conformity with generally
     accepted accounting principles and to maintain accountability for assets,
     (iii) access to assets is permitted only in accordance with management's
     general or specific authorization, and (iv) the recorded accountability for
     assets is compared with existing assets at reasonable intervals and
     appropriate action is taken with respect to any differences.

          (cc) There are no outstanding loans, advances (except normal advances
     for business expenses in the ordinary course of business) or guarantees of
     indebtedness by the Company to or for the benefit of any of the officers or
     directors of the Company or any subsidiary or any of the members of the
     families of any of them that are required to be disclosed in the
     Registration Statement and Prospectus that are not so disclosed.

          (dd) Except as set forth in the Registration Statement and Prospectus,
     (i) each of the Company and the Subsidiary is in compliance with all rules,
     laws and regulations relating to the use, treatment, storage and disposal
     of toxic substances and protection of health or the environment
     ("Environmental Laws") which are applicable to its business, (ii) neither
     the Company nor the Subsidiary has received notice from any governmental
     authority or third party of an asserted claim under Environmental Laws,
     which claim is required to be disclosed in the Registration Statement and
     the Prospectus, (iii) to its knowledge, neither the Company nor the
     Subsidiary has conducted any activities that would require it to make
     future material capital expenditures to comply with Environmental Laws and
     (iv) no property which is owned, leased or occupied by the Company or the
     Subsidiary has been designated as a Superfund site pursuant to the
     Comprehensive Response, Compensation, and Liability Act of 1980, as amended
     (42 U.S.C. Section 9601, ET SEQ.), or otherwise designated as a
     contaminated site under applicable state or local law.

                                    -10-

<PAGE>

          (ee) The agreements to which the Company or the Subsidiary is a party
     described in the Registration Statement and Prospectus are valid
     agreements, enforceable by the Company and the Subsidiary (as applicable)
     except as the enforcement thereof may be limited by applicable bankruptcy,
     insolvency, reorganization, moratorium or other similar laws relating to or
     affecting creditors' rights generally or by general equitable principles
     and, to the best of the Company's knowledge, the other contracting party or
     parties thereto are not in material breach or material default under any of
     such agreements.

          (ff) The Company has not distributed and will not distribute prior to
     the later of (i) the Closing Date, or any date on which Option Shares are
     to be purchased, as the case may be, and (ii) completion of the
     distribution of the Shares, any offering material in connection with the
     offering and sale of the Shares other than any Preliminary Prospectuses,
     the Prospectus, the Registration Statement and other materials, if any,
     permitted by the Act.

          (gg) All outstanding shares of capital stock of the Company have been
     issued in compliance with all federal and state securities laws, were not
     issued in violation of or subject to any preemptive rights or other rights
     to subscribe for or purchase securities, and the authorized and outstanding
     capital stock of the Company is as set forth in the Prospectus under the
     caption "Capitalization" as of the date stated therein and conforms in all
     material respects to the statements relating thereto contained in the
     Registration Statement and the Prospectus (and such statements correctly
     state the substance of the instruments defining the capitalization of the
     Company in all material respects); the Firm Shares and the Option Shares
     have been duly authorized for issuance and sale to the Underwriters
     pursuant to this Agreement and, when issued and delivered by the Company
     against payment therefor in accordance with the terms of this Agreement,
     will be duly and validly issued and fully paid and nonassessable, and will
     be sold free and clear of any pledge, lien, security interest, encumbrance,
     claim or equitable interest; and no preemptive right, co-sale right,
     registration right, right of first refusal or other similar right of
     stockholders exists with respect to any of the Firm Shares or Option Shares
     or the issuance and sale thereof other than those that have been expressly
     waived prior to the date hereof and those that will automatically expire
     upon and will not apply to the consummation of the transactions
     contemplated on the Closing Date.  No further approval or authorization of
     any stockholder, the Board of Directors of the Company or others is
     required for the issuance and sale or transfer of the Shares except as may
     be required under the Act or the Exchange Act or under state or other
     securities or blue sky laws.  All issued and outstanding shares of capital
     stock of each subsidiary of the Company have been duly authorized and
     validly issued and are fully paid and nonassessable, and were not issued in
     violation of or subject to any preemptive right or other rights to
     subscribe for or purchase shares and are owned by the Company free and
     clear of any pledge, lien, security interest, encumbrance, claim or
     equitable interest.  Except as disclosed in the Prospectus and the
     financial statements of the Company, and the related notes thereto,
     included in the Prospectus, the Company does not have has outstandng any
     options to purchase, or any preemptive rights or other rights to subscribe
     for or to purchase, any securities or obligations convertible into, or any
     contracts or commitments to issue or sell, shares of its capital stock or
     any such options, 


                                     -11-

<PAGE>

     rights, convertible securities or obligations.  The description of the 
     Company's stock option, stock bonus and other stock plans or arrangements,
     and the options or other rights granted and exercised thereunder, set 
     forth in the Prospectus accurately and fairly presents the information 
     required to be shown with respect to such plans, arrangements, options 
     and rights.  

     SECTION 3.     REPRESENTATIONS AND WARRANTIES OF THE UNDERWRITERS.  The 
Representatives, on behalf of the several Underwriters, represent and warrant 
to the Company that the information set forth (a) on the cover page of the 
Prospectus with respect to price, underwriting discount and terms of the 
offering and (b) under "Underwriting" in the Prospectus was furnished to the 
Company by and on behalf of the Underwriters for use in connection with the 
preparation of the Registration Statement and is correct and complete in all 
material respects.

     SECTION 4.     PURCHASE, SALE AND DELIVERY OF SHARES.  On the basis of 
the representations, warranties and agreements herein contained, but subject 
to the terms and conditions herein set forth, the Company agrees to sell to 
the Underwriters named in Schedule A hereto, and the Underwriters agree, 
severally and not jointly, to purchase the Firm Shares from the Company at 
the price per share set forth in the Pricing Agreement.  The obligation of 
each Underwriter to the Company shall be to purchase from the Company that 
number of full shares which (as nearly as practicable, as determined by you) 
bears to ________________, the same proportion as the number of Shares set 
forth opposite the name of such Underwriter in Schedule A hereto bears to the 
total number of Firm Shares to be purchased by all Underwriters under this 
Agreement.  The initial public offering price and the purchase price shall be 
set forth in the Pricing Agreement.

     At 9:00 A.M., Chicago Time, on the fourth business day, if permitted 
under Rule 15c6-1 under the Exchange Act, (or the third business day if 
required under Rule 15c6-1 under the Exchange Act or unless postponed in 
accordance with the provisions of Section 12) following the date the 
Registration Statement becomes effective (or, if the Company has elected to 
rely upon Rule 430A, the fourth business day, if permitted under Rule 15c6-1 
under the Exchange Act, (or the third business day if required under Rule 
15c6-1 under the Exchange Act) after execution of the Pricing Agreement), or 
such other time not later than ten business days after such date as shall be 
agreed upon by the Representatives and the Company, the Company will deliver 
to you at the offices of counsel for the Underwriters or through the 
facilities of The Depository Trust Company for the accounts of the several 
Underwriters, certificates representing the Firm Shares to be sold by it 
against payment of the purchase price therefor by delivery of federal or 
other immediately available funds, by wire transfer or otherwise, to the 
Company.  Such time of delivery and payment is herein referred to as the 
"First Closing Date." The certificates for the Firm Shares so to be delivered 
will be in such denominations and registered in such names as you request by 
notice to the Company prior to 10:00 A.M., Chicago Time, on the second full 
business day preceding the First Closing Date, and will be made available at 
the Company's expense for checking and packaging by the Representatives at 
10:00 A.M., Chicago Time, on the business day preceding the First Closing 
Date. Payment for the Firm Shares so to be delivered shall be made at the 
time and in the manner described above at the offices of counsel for the 
Underwriters.


                                     -12-

<PAGE>

     In addition, on the basis of the representations, warranties and 
agreements herein contained, but subject to the terms and conditions herein 
set forth, the Company hereby grants an option to the several Underwriters to 
purchase, severally and not jointly, up to an aggregate of ________ Option 
Shares, at the same purchase price per share to be paid for the Firm Shares, 
for use solely in covering any overallotments made by the Underwriters in the 
sale and distribution of the Firm Shares.  The option granted hereunder may 
be exercised at any time (but not more than once) within 30 days after the 
date of the initial public offering upon notice by you to the Company setting 
forth the aggregate number of Option Shares as to which the Underwriters are 
exercising the option, the names and denominations in which the certificates 
for such shares are to be registered and the time and place at which such 
certificates will be delivered.  Such time of delivery (which may not be 
earlier than the First Closing Date), being herein referred to as the "Second 
Closing Date," shall be determined by you, but if at any time other than the 
First Closing Date, shall not be earlier than three nor later than 10 full 
business days after delivery of such notice of exercise.  The number of 
Option Shares to be purchased by each Underwriter shall be determined by 
multiplying the number of Option Shares to be sold by a fraction, the 
numerator of which is the number of Firm Shares to be purchased by such 
Underwriter as set forth opposite its name in Schedule A and the denominator 
of which is the total number of Firm Shares (subject to such adjustments to 
eliminate any fractional share purchases as you in your absolute discretion 
may make).  Certificates for the Option Shares will be made available at the 
Company's expense for checking and packaging at 10:00 A.M., Chicago Time, on 
the first full business day preceding the Second Closing Date.  The manner of 
payment for and delivery of the Option Shares shall be the same as for the 
Firm Shares as specified in the preceding paragraph.

     You have advised the Company that each Underwriter has authorized you to 
accept delivery of its Shares, to make payment and to receipt therefor.  You, 
individually and not as the Representatives of the Underwriters, may make 
payment for any Shares to be purchased by any Underwriter whose funds shall 
not have been received by you by the First Closing Date or the Second Closing 
Date, as the case may be, for the account of such Underwriter, but any such 
payment shall not relieve such Underwriter from any obligation hereunder.

     SECTION 5.     COVENANTS OF THE COMPANY.  The Company covenants and 
agrees that:

          (a)  The Company will advise you promptly of the issuance by the
     Commission of any stop order suspending the effectiveness of the
     Registration Statement or of the institution of any proceedings for that
     purpose, or of any notification of the suspension of qualification of the
     Shares for sale in any jurisdiction or the initiation or threatening of any
     proceedings for that purpose, and will also advise you promptly of any
     request of the Commission for amendment or supplement of the Registration
     Statement, of any preliminary prospectus or of the Prospectus, or for
     additional information.

          (b)  The Company will give you notice of its intention to file or
     prepare any amendment to the Registration Statement (including any post-
     effective amendment) or any Rule 462(b) 


                                     -13-

<PAGE>

     Registration Statement or any amendment or supplement to the Prospectus 
     (including any revised prospectus which the Company proposes for use by 
     the Underwriters in connection with the offering of the Shares which 
     differs from the prospectus on file at the Commission at the time the 
     Registration Statement became or becomes effective, whether or not such 
     revised prospectus is required to be filed pursuant to Rule 424(b) and 
     any term sheet as contemplated by Rule 434) and will furnish you with 
     copies of any such amendment or supplement a reasonable amount of time 
     prior to such proposed filing or use, as the case may be, and will not 
     file any such amendment or supplement or use any such prospectus to 
     which you or counsel for the Underwriters shall reasonably object.

          (c)  If the Company elects to rely on Rule 434 of the 1933 Act, the
     Company will prepare a term sheet that complies with the requirements of
     Rule 434.  If the Company elects not to rely on Rule 434, the Company will
     provide the Underwriters with copies of the form of prospectus, in such
     numbers as the Underwriters may reasonably request, and file with the
     Commission such prospectus in accordance with Rule 424(b) of the 1933 Act
     by the close of business in New York City on the second business day
     immediately succeeding the date of the Pricing Agreement.  If the Company
     elects to rely on Rule 434, the Company will provide the Underwriters with
     copies of the form of Rule 434 Prospectus, in such numbers as the
     Underwriters may reasonably request, by the close of business in New York
     on the business day immediately succeeding the date of the Pricing
     Agreement.

          (d)  If at any time when a prospectus relating to the Shares is
     required to be delivered under the 1933 Act any event occurs as a result of
     which the Prospectus, including any amendments or supplements, would
     include an untrue statement of a material fact, or omit to state any
     material fact required to be stated therein or necessary to make the
     statements therein, in the light of the circumstances under which they were
     made, not misleading, or if it is necessary at any time to amend the
     Prospectus, including any amendments or supplements thereto and including
     any revised prospectus which the Company proposes for use by the
     Underwriters in connection with the offering of the Shares which differs
     from the prospectus on file with the Commission at the time of
     effectiveness of the Registration Statement, whether or not such revised
     prospectus is required to be filed pursuant to Rule 424(b) to comply with
     the 1933 Act, the Company promptly will advise you thereof and will
     promptly prepare and file with the Commission an amendment or supplement
     which will correct such statement or omission or an amendment which will
     effect such compliance; and, in case any Underwriter is required to deliver
     a prospectus nine months or more after the effective date of the
     Registration Statement, the Company upon request, but at the expense of
     such Underwriter, will prepare promptly such prospectus or prospectuses as
     may be necessary to permit compliance with the requirements of Section
     10(a)(3) of the 1933 Act.

          (e)  Neither the Company nor any of its subsidiaries will, prior to
     the earlier of the Second Closing Date or termination or expiration of the
     related option, incur any liability or obligation, direct or contingent, or
     enter into any material transaction, other than in the ordinary course of
     business, except as contemplated by the Prospectus.


                                      -14-

<PAGE>

          (f)  Neither the Company nor any of its subsidiaries will acquire any
     capital stock of the Company prior to the earlier of the Second Closing
     Date or termination or expiration of the related option nor will the
     Company declare or pay any dividend or make any other distribution upon the
     Common Stock payable to stockholders of record on a date prior to the
     earlier of the Second Closing Date or termination or expiration of the
     related option, except in either case as contemplated by the Prospectus.

          (g)  Not later than November 30, 1999 the Company will make generally
     available to its securityholders an earnings statement (which need not be
     audited) covering a period of at least 12 months beginning after the
     effective date of the Registration Statement, which will satisfy the
     provisions of the last paragraph of Section 11(a) of the 1933 Act.

          (h)  During such period as a prospectus is required by law to be
     delivered in connection with offers and sales of the Shares by an
     Underwriter or dealer, the Company will furnish to you at its expense,
     subject to the provisions of subsection (d) hereof, copies of the
     Registration Statement, the Prospectus, each preliminary prospectus and all
     amendments and supplements to any such documents in each case as soon as
     available and in such quantities as you may reasonably request, for the
     purposes contemplated by the 1933 Act.

          (i)  The Company will cooperate with the Underwriters in qualifying or
     registering the Shares for sale under the blue sky laws of such
     jurisdictions as you designate, and will continue such qualifications in
     effect so long as reasonably required for the distribution of the Shares. 
     The Company shall not be required to qualify as a foreign corporation or to
     file a general consent to service of process in any such jurisdiction where
     it is not currently qualified or where it would be subject to taxation as a
     foreign corporation.

          (j)  During the period of five years hereafter, the Company will
     furnish you and each of the other Underwriters with a copy (i) as soon as
     practicable after the filing thereof, of each report filed by the Company
     with the Commission, any securities exchange or the NASD; (ii) as soon as
     practicable after the release thereof, of each material press release in
     respect of the Company; and (iii) as soon as available, of each report of
     the Company mailed to stockholders.

          (k)  The Company will use the net proceeds received by it from the
     sale of the Shares being sold by it in the manner specified in the
     Prospectus.

          (l)  If, at the time of effectiveness of the Registration Statement,
     any information shall have been omitted therefrom in reliance upon Rule
     430A and/or Rule 434, then immediately following the execution of the
     Pricing Agreement, the Company will prepare, and file or transmit for
     filing with the Commission in accordance with such Rule 430A, Rule 424(b)
     and/or Rule 434, copies of an amended Prospectus, or, if required by such
     Rule 430A and/or Rule 434, a post-effective 


                                     -15-

<PAGE>

     amendment to the Registration Statement (including an amended Prospectus), 
     containing all information so omitted.  If required, the Company will 
     prepare and file, or transmit for filing, a Rule 462(b) Registration 
     Statement not later than the date of the execution of the Pricing 
     Agreement.  If a Rule 462(b) Registration Statement is filed, the Company 
     shall make payment of, or arrange for payment of, the additional 
     registration fee owing to the Commission required by Rule 111.

          (m)  The Company will comply with all registration, filing and
     reporting requirements of the Exchange Act and the Nasdaq National Market.

     SECTION 6.     PAYMENT OF EXPENSES.  Whether or not the transactions 
contemplated hereunder are consummated or this Agreement becomes effective as 
to all of its provisions or is terminated, the Company agrees to pay (i) all 
costs, fees and expenses (other than legal fees and disbursements of counsel 
for the Underwriters and the expenses incurred by the Underwriters) incurred 
in connection with the performance of the Company's obligations hereunder, 
including without limiting the generality of the foregoing, all fees and 
expenses of legal counsel for the Company and of the Company's independent 
accountants, all costs and expenses incurred in connection with the 
preparation, printing, filing and distribution of the Registration Statement, 
each preliminary prospectus and the Prospectus (including exhibits and 
financial statements) and all amendments and supplements provided for herein, 
this Agreement, the Pricing Agreement and the blue sky Memorandum, (ii) all 
costs, fees and expenses (including legal fees not to exceed $__________ and 
disbursements of counsel for the Underwriters) incurred by the Underwriters 
in connection with qualifying or registering all or any part of the Shares 
for offer and sale under blue sky laws, including the preparation of a blue 
sky memorandum relating to the Shares and clearance of such offering with the 
NASD; and (iii) all fees and expenses of the Company's transfer agent, 
printing of the certificates for the Shares and all transfer taxes, if any, 
with respect to the sale and delivery of the Shares to the several 
Underwriters.

     SECTION 7.     CONDITIONS OF THE OBLIGATIONS OF THE UNDERWRITERS.  The 
obligations of the several Underwriters to purchase and pay for the Firm 
Shares on the First Closing Date and the Option Shares on the Second Closing 
Date shall be subject to the accuracy of the representations and warranties 
on the part of the Company herein set forth as of the date hereof and as of 
the First Closing Date or the Second Closing Date, as the case may be, to the 
accuracy of the statements of officers of the Company made pursuant to the 
provisions hereof, to the performance by the Company of its obligations 
hereunder, and to the following additional conditions:

          (a)  The Registration Statement shall have become effective either
     prior to the execution of this Agreement or not later than 1:00 P.M.,
     Chicago Time, on the first full business day after the date of this
     Agreement, or such later time as shall have been consented to by you but in
     no event later than 1:00 P.M., Chicago Time, on the third full business day
     following the date hereof; and prior to the First Closing Date or the
     Second Closing Date, as the case may be, no stop order suspending the
     effectiveness of the Registration Statement shall have been issued and no
     proceedings for that purpose shall have been instituted or shall be pending
     or, to the knowledge of the Company or you, shall be 


                                     -16-

<PAGE>

     contemplated by the Commission.  If the Company has elected to rely upon 
     Rule 430A and/or Rule 434, the information concerning the initial public 
     offering price of the Shares and price-related information shall have 
     been transmitted to the Commission for filing pursuant to Rule 424(b) 
     within the prescribed period and the Company will provide evidence 
     satisfactory to the Representatives of such timely filing (or a 
     post-effective amendment providing such information shall have been 
     filed and declared effective in accordance with the requirements of 
     Rules 430A and 424(b)).  If a Rule 462(b) Registration Statement is 
     required, such Registration Statement shall have been transmitted to the 
     Commission for filing and become effective within the prescribed time 
     period and, prior to the First Closing Date, the Company shall have 
     provided evidence of such filing and effectiveness in accordance with 
     Rule 462(b).

          (b)  The Shares shall have been qualified for sale under the blue sky
     laws of such states as shall have been specified by the Representatives.

          (c)  The legality and sufficiency of the authorization, issuance and
     sale or transfer and sale of the Shares hereunder, the validity and form of
     the certificates representing the Shares, the execution and delivery of
     this Agreement and the Pricing Agreement, and all corporate proceedings and
     other legal matters incident thereto, and the form of the Registration
     Statement and the Prospectus (except financial statements) shall have been
     approved by counsel for the Underwriters exercising reasonable judgment.

          (d)  You shall not have advised the Company that the Registration
     Statement or the Prospectus or any amendment or supplement thereto,
     contains an untrue statement of fact, which, in the opinion of counsel for
     the Underwriters, is material or omits to state a fact which, in the
     opinion of such counsel, is material and is required to be stated therein
     or necessary to make the statements therein not misleading.

          (e)  Subsequent to the execution and delivery of this Agreement, there
     shall not have occurred any change, or any development involving a
     prospective change, in or affecting particularly the business or properties
     of the Company or its subsidiaries, whether or not arising in the ordinary
     course of business, which, in the judgment of the Representatives, makes it
     impractical or inadvisable to proceed with the public offering or purchase
     of the Shares as contemplated hereby.

          (f)  There shall have been furnished to you, as Representatives of the
     Underwriters, on the First Closing Date or the Second Closing Date, as the
     case may be, except as otherwise expressly provided below:

               (i)    An opinion of Wilson Sonsini Goodrich & Rosati, P.C., 
          counsel for the Company, addressed to the Underwriters and dated the 
          First Closing Date or the Second Closing Date, as the case may be, 
          to the effect that:


                                      -17-

<PAGE>

                    (1)  The Company has been duly incorporated and is 
          validly existing as a corporation in good standing under the laws 
          of the jurisdiction of its incorporation;

                    (2)  The Company has the corporate power and authority to 
          own, lease and operate its properties and to conduct its business 
          as described in the Prospectus;

                    (3)  The Company is duly qualified to do business as a 
          foreign corporation and is in good standing in each jurisdiction, 
          if any, in which the ownership or leasing of its properties or the 
          conduct of its business requires such qualification, except where 
          the failure to be so qualified or be in good standing would not 
          have a material adverse effect on the condition (financial or 
          otherwise), earnings, operations or business of the Company and the 
          Subsidiary considered as one enterprise.  To such counsel's 
          knowledge, the Company does not own or control, directly or 
          indirectly, any corporation, association or other entity other than 
          BeneSphere Administrators, Inc.;

                    (4)  The authorized, issued and outstanding capital stock 
          of the Company is as set forth in the Prospectus under the caption 
          "Capitalization" as of the date stated therein, the issued and 
          outstanding shares of capital stock of the Company have been duly 
          and validly issued and are fully paid and nonassessable, and, to 
          such counsel's knowledge, will not have been issued in violation of 
          or subject to any preemptive right, co-sale right, registration 
          right, right of first refusal or other similar right;

                    (5)  The Firm Shares or the Option Shares, as the case 
          may be, to be issued by the Company pursuant to the terms of this 
          Agreement have been duly authorized and, upon issuance and delivery 
          against payment therefor in accordance with the terms hereof, will 
          be duly and validly issued and fully paid and nonassessable, and 
          will not have been issued in violation of or subject to any 
          preemptive right, co-sale right, registration right, right of first 
          refusal or other similar right;

                    (6)  The Company has the corporate power and authority to 
          enter into this Agreement and to issue, sell and deliver to the 
          Underwriters the Shares to be issued and sold by it hereunder;

                    (7)  This Agreement has been duly authorized by all 
          necessary corporate action on the part of the Company and has been 
          duly executed and delivered by the Company and, assuming due 
          authorization, execution and delivery by you, is a valid and 
          binding agreement of the Company, enforceable in accordance with 
          its terms, except insofar as indemnification provisions may be 
          limited by applicable law and except as enforceability may be 
          limited by bankruptcy, insolvency, reorganization, moratorium or 
          similar laws relating to or affecting creditors' rights generally 
          or by general equitable principles;


                                     -18-

<PAGE>

                    (8)  The Registration Statement has become effective 
          under the Act and, to such counsel's knowledge, no stop order 
          suspending the effectiveness of the Registration Statement has been 
          issued and no proceedings for that purpose have been instituted or 
          are pending or threatened under the Act;

                    (9)  The Registration Statement and the Prospectus, and 
          each amendment or supplement thereto (other than the financial 
          statements, including supporting schedules, and financial data 
          derived therefrom, as to which such counsel need express no 
          opinion), as of the effective date of the Registration Statement, 
          complied as to form in all material respects with the requirements 
          of the Act and the applicable Rules and Regulations;

                    (10) The information in the Prospectus under the caption 
          "Description of Capital Stock," to the extent that it constitutes 
          matters of law or legal conclusions, has been reviewed by such 
          counsel and is a fair summary of such matters and conclusions; and 
          the forms of certificates evidencing the Common Stock and filed as 
          exhibits to the Registration Statement comply with Delaware law;

                    (11) The description in the Registration Statement and 
          the Prospectus of the charter and bylaws of the Company and of 
          federal statutes and the General Corporation Law of the State of 
          Delaware are accurate summaries thereof and fairly present the 
          information required to be presented by the Act and the applicable 
          Rules and Regulations;

                    (12) To such counsel's knowledge, there are no 
          agreements, contracts, leases or documents to which the Company is 
          a party of a character required to be described or referred to in 
          the Registration Statement or Prospectus or to be filed as an 
          exhibit to the Registration Statement which are not described or 
          referred to therein or filed as required;

                    (13) The performance of this Agreement and the 
          consummation of the transactions herein contemplated (other than 
          performance of the Company's indemnification obligations hereunder, 
          concerning which no opinion need be expressed) will not (a) result 
          in any violation of the Company's charter or bylaws or (b) to such 
          counsel's knowledge, result in a material breach or violation of 
          any of the terms and provisions of, or constitute a material 
          default under, any material bond, debenture, note or other evidence 
          of indebtedness, or any material lease, contract, indenture, 
          mortgage, deed of trust, loan agreement, joint venture or other 
          agreement or instrument known to such counsel to which the Company 
          is a party or by which its properties are bound, or any applicable 
          statute, rule or regulation known to such counsel or, to such 
          counsel's knowledge, any material order, writ or decree of any 
          court, government or governmental agency or body having 
          jurisdiction over the Company or over any of its properties or 
          operations;


                                     -19-

<PAGE>

                    (14) No consent, approval, authorization or order of or 
          qualification with any court, government or governmental agency or 
          body having jurisdiction over the Company or over any of its 
          properties or operations is necessary in connection with the 
          consummation by the Company of the transactions herein 
          contemplated, except such as have been obtained under the Act or 
          such as may be required under state or other securities or Blue Sky 
          laws in connection with the purchase and the distribution of the 
          Shares by the Underwriters;

                    (15) To such counsel's knowledge, there are no legal or 
          governmental proceedings pending or threatened against the Company 
          or the Subsidiary of a character required to be disclosed in the 
          Registration Statement or the Prospectus by the Act or the Rules 
          and Regulations, other than those described therein;

                    (16) To such counsel's knowledge, the Company is not 
          presently (a) in material violation of its charter or bylaws or (b) 
          in material breach of any order, writ or decree of any court or 
          governmental agency or body having jurisdiction over the Company or 
          over any of its properties or operations; and

                    (17) To such counsel's knowledge, except as set forth in 
          the Registration Statement and Prospectus, no holders of Common 
          Stock or other securities of the Company have registration rights 
          with respect to securities of the Company and, except as set forth 
          in the Registration Statement and Prospectus, all holders of 
          securities of the Company having rights known to such counsel to 
          registration of such shares of Common Stock or other securities, 
          because of the filing of the Registration Statement by the Company 
          have, with respect to the offering contemplated by this Agreement, 
          waived such rights or such rights have expired by reason of lapse 
          of time following notification of the Company's intent to file the 
          Registration Statement.
          

              In addition, such counsel shall state that such counsel has 
          participated in conferences with certain officers and other 
          representatives of the Company, including its independent certified 
          public accountants and with you and your counsel, at which such 
          conferences the contents of the Registration Statement and the 
          Prospectus and related matters were discussed, and although they 
          have not independently verified the accuracy, completeness or 
          fairness of such information, nothing has come to the attention of 
          such counsel which leads them to believe that, at the time the 
          Registration Statement became effective and at all times subsequent 
          thereto up to and on the Closing Date and on any later date on 
          which Option Shares are to be purchased, the Registration Statement 
          (other than the financial statements, including supporting 
          schedules, and other financial and statistical information derived 
          therefrom, as to which such counsel need express no comment) 
          contained any untrue statement of a material fact or omitted to 
          state a material fact required to be stated therein or necessary to 
          make the 


                                     -20-

<PAGE>


     statements therein not misleading, or at the Closing Date or
     any later date on which the Option Shares are to be purchased, as the case
     may be, the Prospectus (except as aforesaid) contained any untrue statement
     of a material fact or omitted to state a material fact necessary to make
     the statements therein, in the light of the circumstances under which they
     were made, not misleading.

          Counsel rendering the foregoing opinion may rely as to questions
     of law not involving the laws of the United States or the State of
     California and Delaware upon opinions of local counsel, and as to
     questions of fact upon representations or certificates of officers of
     the Company, and of government officials, in which case their opinion
     is to state that they are so relying and that they have no knowledge
     of any material misstatement or inaccuracy in any such opinion,
     representation or certificate.  Copies of any opinion, representation
     or certificate so relied upon shall be delivered to you, as
     Representatives of the Underwriters, and to Underwriters' Counsel.

          In rendering such opinion, such counsel may state that they are
     relying upon the certificate of Norwest Bank Minnesota, National
     Association, the transfer agent for the Common Stock, as to the number of
     shares of Common Stock at any time or times outstanding, and that insofar
     as their opinion under clause (7) above relates to the accuracy and
     completeness of the Prospectus and Registration Statement, it is based upon
     a general review with the Company's representatives and independent
     accountants of the information contained therein, without independent
     verification by such counsel of the accuracy or completeness of such
     information.  Such counsel may also rely upon the opinions of other
     competent counsel and, as to factual matters, on certificates of officers
     of the Company and of state officials, in which case their opinion is to
     state that they are so doing and copies of said opinions or certificates
     are to be attached to the opinion unless said opinions or certificates (or,
     in the case of certificates, the information therein) have been furnished
     to the Representatives in other form.

          (ii) Such opinion or opinions of Wilson Sonsini Goodrich & Rosati,
     P.C., counsel for the Underwriters, dated the First Closing Date or the
     Second Closing Date, as the case may be, with respect to the incorporation
     of the Company, the validity of the Shares, the Registration Statement and
     the Prospectus and other related matters as you may reasonably require, and
     the Company shall have furnished to such counsel such documents and shall
     have exhibited to them such papers and records as they request for the
     purpose of enabling them to pass upon such matters.

          (iii)     A certificate of the chief executive officer and the chief
     financial officer of the Company, dated the First Closing Date or the
     Second Closing Date, as the case may be, to the effect that:


                                    -21-

<PAGE>


               (1)  the representations and warranties of the Company set 
          forth in Section 2 of this Agreement are true and correct as of the 
          date of this Agreement and as of the First Closing Date or the 
          Second Closing Date, as the case may be, and the Company has 
          complied with all the agreements and satisfied all the conditions 
          on its part to be performed or satisfied at or prior to such 
          Closing Date; and
          
               (2)  the Commission has not issued an order preventing or 
          suspending the use of the Prospectus or any preliminary prospectus 
          filed as a part of the Registration Statement or any amendment 
          thereto; no stop order suspending the effectiveness of the 
          Registration Statement has been issued; and to the best knowledge 
          of the respective signers, no proceedings for that purpose have 
          been instituted or are pending or contemplated under the 1933 Act.

          The delivery of the certificate provided for in this subparagraph
     shall be and constitute a representation and warranty of the Company as to
     the facts required in the immediately foregoing clauses (1) and (2) of this
     subparagraph to be set forth in said certificate.

          (iv) At the time the Pricing Agreement is executed and also on the
     First Closing Date or the Second Closing Date, as the case may be, there
     shall be delivered to you a letter addressed to you, as Representatives of
     the Underwriters, from Ernst & Young, LLP independent auditors, the first
     one to be dated the date of the Pricing Agreement, the second one to be
     dated the First Closing Date and the third one (in the event of a second
     closing) to be dated the Second Closing Date, to the effect set forth in
     Schedule B.  There shall not have been any change or decrease specified in
     the letters referred to in this subparagraph which makes it impractical or
     inadvisable in the judgment of the Representatives to proceed with the
     public offering or purchase of the Shares as contemplated hereby.

          (v)  Such further certificates and documents as you may reasonably
     request.

     All such opinions, certificates, letters and documents shall be in
compliance with the provisions hereof only if they are satisfactory to you and
to Cooley Godward LLP, counsel for the Underwriters, which approval shall not be
unreasonably withheld.  The Company shall furnish you with such manually signed
or conformed copies of such opinions, certificates, letters and documents as you
request.

     If any condition to the Underwriters' obligations hereunder to be 
satisfied prior to or at the First Closing Date is not so satisfied, this 
Agreement at your election will terminate upon notification to the Company 
without liability on the part of any Underwriter or the Company, except for 
the expenses to be paid or reimbursed by the Company pursuant to Sections 6 
and 10 hereof and except to the extent provided in Section 11 hereof.


                                    -22-

<PAGE>

     SECTION 8.     REIMBURSEMENT OF UNDERWRITERS' EXPENSES.  If the sale to the
Underwriters of the Shares on the First Closing Date is not consummated because
any condition of the Underwriters' obligations hereunder is not satisfied or
because of any refusal, inability or failure on the part of the Company to
perform any agreement herein or to comply with any provision hereof, unless such
failure to satisfy such condition or to comply with any provision hereof is due
to the default or omission of any Underwriter, the Company agrees to reimburse
you and the other Underwriters upon demand for all out-of-pocket expenses
(including reasonable fees and disbursements of counsel) that shall have been
reasonably incurred by you and them in connection with the proposed purchase and
the sale of the Shares.  Any such termination shall be without liability of any
party to any other party except that the provisions of this Section, Section 6
and Section 10 shall at all times be effective and shall apply.

     SECTION 9.     EFFECTIVENESS OF REGISTRATION STATEMENT.  You and the
Company will use your and its best efforts to cause the Registration Statement
to become effective, if it has not yet become effective, and to prevent the
issuance of any stop order suspending the effectiveness of the Registration
Statement and, if such stop order be issued, to obtain as soon as possible the
lifting thereof.

     SECTION 10.    INDEMNIFICATION.  (a) The Company agrees to indemnify and
hold harmless each Underwriter and each person, if any, who controls any
Underwriter within the meaning of the 1933 Act or the Exchange Act against any
losses, claims, damages or liabilities, joint or several, to which such
Underwriter or such controlling person may become subject under the 1933 Act,
the Exchange Act or other federal or state statutory law or regulation, at
common law or otherwise (including in settlement of any litigation if such
settlement is effected with the written consent of the Company, insofar as such
losses, claims, damages or liabilities (or actions in respect thereof) arise out
of or are based upon any untrue statement or alleged untrue statement of any
material fact contained in the Registration Statement, including the information
deemed to be part of the Registration Statement at the time of effectiveness
pursuant to Rule 430A and/or Rule 434, if applicable, any preliminary
prospectus, the Prospectus, or any amendment or supplement thereto, or arise out
of or are based upon the omission or alleged omission to state therein a
material fact required to be stated therein or necessary to make the statements
therein not misleading; and will reimburse each Underwriter and each such
controlling person for any legal or other expenses reasonably incurred by such
Underwriter or such controlling person in connection with investigating or
defending any such loss, claim, damage, liability or action; PROVIDED, HOWEVER,
that the Company will not be liable in any such case to the extent that (i) any
such loss, claim, damage or liability arises out of or is based upon an untrue
statement or alleged untrue statement or omission or alleged omission made in
the Registration Statement, any preliminary prospectus, the Prospectus or any
amendment or supplement thereto in reliance upon and in conformity with written
information furnished to the Company by or on behalf of any Underwriter through
the Representatives, specifically for use therein; or (ii) if such statement or
omission was contained or made in any preliminary prospectus and corrected in
the Prospectus and (1) any such loss, claim, damage or liability suffered or
incurred by any Underwriter (or any person who controls any Underwriter)
resulted from an action, claim or suit by any person who purchased Shares which
are the subject thereof from such Underwriter in the offering and (2) such
Underwriter failed to deliver or provide a copy of the Prospectus to such person
at or prior to the confirmation 

                                     -23-

<PAGE>


of the sale of such Shares in any case where such delivery is required by the 
1933 Act.  In addition to its other obligations under this Section 10(a), the 
Company agrees that, as an interim measure during the pendency of any claim, 
action, investigation, inquiry or other proceeding arising out of or based 
upon any statement or omission, or any alleged statement or omission, 
described in this Section 10(a), it will reimburse the Underwriters on a 
monthly basis for all reasonable legal and other expenses incurred in 
connection with investigating or defending any such claim, action, 
investigation, inquiry or other proceeding, notwithstanding the absence of a 
judicial determination as to the propriety and enforceability of the 
Company's obligation to reimburse the Underwriters for such expenses and the 
possibility that such payments might later be held to have been improper by a 
court of competent jurisdiction.  This indemnity agreement will be in 
addition to any liability which the Company may otherwise have.

     (b)  Each Underwriter will severally indemnify and hold harmless the
Company, each of its directors, each of its officers who signed the Registration
Statement and each person, if any, who controls the Company within the meaning
of the 1933 Act or the Exchange Act, against any losses, claims, damages or
liabilities to which the Company, or any such director, officer or controlling
person may become subject under the 1933 Act, the Exchange Act or other federal
or state statutory law or regulation, at common law or otherwise (including in
settlement of any litigation, if such settlement is effected with the written
consent of such Underwriter), insofar as such losses, claims, damages or
liabilities (or actions in respect thereof) arise out of or are based upon any
untrue or alleged untrue statement of any material fact contained in the
Registration Statement, any preliminary prospectus, the Prospectus, or any
amendment or supplement thereto, or arise out of or are based upon the omission
or alleged omission to state therein a material fact required to be stated
therein or necessary to make the statements therein not misleading, in each case
to the extent, but only to the extent, that such untrue statement or alleged
untrue statement or omission or alleged omission was made in the Registration
Statement, any preliminary prospectus, the Prospectus, or any amendment or
supplement thereto in reliance upon and in conformity with Section 3 of this
Agreement or any other written information furnished to the Company by such
Underwriter through the Representatives specifically for use in the preparation
thereof; and will reimburse any legal or other expenses reasonably incurred by
the Company, or any such director, officer or controlling person in connection
with investigating or defending any such loss, claim, damage, liability or
action.  In addition to their other obligations under this Section 10(b), the
Underwriters agree that, as an interim measure during the pendency of any claim,
action, investigation, inquiry or other proceeding arising out of or based upon
any statement or omission, or any alleged statement or omission, described in
this Section 10(b), they will reimburse the Company on a monthly basis for all
reasonable legal and other expenses incurred in connection with investigating or
defending any such claim, action, investigation, inquiry or other proceeding,
notwithstanding the absence of a judicial determination as to the propriety and
enforceability of the Underwriters' obligation to reimburse the Company for such
expenses and the possibility that such payments might later be held to have been
improper by a court of competent jurisdiction.  This indemnity agreement will be
in addition to any liability which such Underwriter may otherwise have.

                                      -24-

<PAGE>



     (c)  Promptly after receipt by an indemnified party under this Section of
notice of the commencement of any action, such indemnified party will, if a
claim in respect thereof is to be made against an indemnifying party under this
Section, notify the indemnifying party of the commencement thereof; but the
omission so to notify the indemnifying party will not relieve it from any
liability which it may have to any indemnified party except to the extent that
the indemnifying party was prejudiced by such failure to notify.  In case any
such action is brought against any indemnified party, and it notifies an
indemnifying party of the commencement thereof, the indemnifying party will be
entitled to participate in, and, to the extent that it may wish, jointly with
all other indemnifying parties similarly notified, to assume the defense
thereof, with counsel satisfactory to such indemnified party; PROVIDED, HOWEVER,
if the defendants in any such action include both the indemnified party and the
indemnifying party and the indemnified party shall have reasonably concluded
that there may be legal defenses available to it and/or other indemnified
parties which are different from or additional to those available to the
indemnifying party, or the indemnified and indemnifying parties may have
conflicting interests which would make it inappropriate for the same counsel to
represent both of them, the indemnified party or parties shall have the right to
select separate counsel to assume such legal defense and otherwise to
participate in the defense of such action on behalf of such indemnified party or
parties.  Upon receipt of notice from the indemnifying party to such indemnified
party of its election so to assume the defense of such action and approval by
the indemnified party of counsel, the indemnifying party will not be liable to
such indemnified party under this Section for any legal or other expenses
subsequently incurred by such indemnified party in connection with the defense
thereof unless (i) the indemnified party shall have employed such counsel in
connection with the assumption of legal defense in accordance with the proviso
to the next preceding sentence (it being understood, however, that the
indemnifying party shall not be liable for the expenses of more than one
separate counsel, approved by the Representatives in the case of paragraph (a)
representing all indemnified parties not having different or additional defenses
or potential conflicting interest among themselves who are parties to such
action), (ii) the indemnifying party shall not have employed counsel
satisfactory to the indemnified party to represent the indemnified party within
a reasonable time after notice of commencement of the action or (iii) the
indemnifying party has authorized the employment of counsel for the indemnified
party at the expense of the indemnifying party.  No indemnifying party shall,
without the prior written consent of the indemnifid party, effect any settlement
of any pending or threatened proceeding in respect of which any indemnified
party is or could have been a party and indemnity could have been sought
hereunder by such indemnified party, unless such settlement includes an
unconditional release of such indemnified party from all liability arising out
of such proceeding.

     (d)  If the indemnification provided for in this Section is unavailable to
an indemnified party under paragraphs (a) or (b) hereof in respect of any
losses, claims, damages or liabilities referred to therein, then each applicable
indemnifying party, in lieu of indemnifying such indemnified party, shall
contribute to the amount paid or payable by such indemnified party as a result
of such losses, claims, damages or liabilities (i) in such proportion as is
appropriate to reflect the relative benefits received by the Company and the
Underwriters from the offering of the Shares or (ii) if the allocation provided
by clause (i) above is not permitted by applicable law, in such proportion as is
appropriate to reflect not only the relative benefits referred to in clause (i)
above but also the relative fault of the Company and the Underwriters in
connection 


                                      -25-

<PAGE>



with the statements or omissions which resulted in such losses, claims, 
damages or liabilities, as well as any other relevant equitable 
considerations.  The respective relative benefits received by the Company and 
the Underwriters shall be deemed to be in the same proportion in the case of 
the Company as the total price paid to the Company for the Shares by the 
Underwriters (net of underwriting discount but before deducting expenses), 
and in the case of the Underwriters as the underwriting discount received by 
them bears to the total of such amounts paid to the Company and received by 
the Underwriters as underwriting discount in each case as contemplated by the 
Prospectus.  The relative fault of the Company and the Underwriters shall be 
determined by reference to, among other things, whether the untrue or alleged 
untrue statement of a material fact or the omission to state a material fact 
relates to information supplied by the Company or by the Underwriters and the 
parties' relative intent, knowledge, access to information and opportunity to 
correct or prevent such statement or omission.  The amount paid or payable by 
a party as a result of the losses, claims, damages and liabilities referred 
to above shall be deemed to include any legal or other fees or expenses 
reasonably incurred by such party in connection with investigating or 
defending any action or claim.

     The Company and the Underwriters agree that it would not be just and 
equitable if contribution pursuant to this Section were determined by pro 
rata allocation or by any other method of allocation which does not take 
account of the equitable considerations referred to in the immediately 
preceding paragraph. Notwithstanding the provisions of this Section, no 
Underwriter shall be required to contribute any amount in excess of the 
amount by which the total price at which the Shares underwritten by it and 
distributed to the public were offered to the public exceeds the amount of 
any damages which such Underwriter has otherwise been required to pay by 
reason of such untrue or alleged untrue statement or omission or alleged 
omission.  No person guilty of fraudulent misrepresentation (within the 
meaning of Section 11(f) of the 1933 Act) shall be entitled to contribution 
from any person who was not guilty of such fraudulent misrepresentation.  The 
Underwriters' obligations to contribute pursuant to this Section are several 
in proportion to their respective underwriting commitments and not joint.  

     (e)  The provisions of this Section shall survive any termination of this
Agreement.

     SECTION 11.    DEFAULT OF UNDERWRITERS.  It shall be a condition to the
agreement and obligation of the Company to sell and deliver the Shares
hereunder, and of each Underwriter to purchase the Shares hereunder, that,
except as hereinafter in this paragraph provided, each of the Underwriters shall
purchase and pay for all Shares agreed to be purchased by such Underwriter
hereunder upon tender to the Representatives of all such Shares in accordance
with the terms hereof.  If any Underwriter or Underwriters default in their
obligations to purchase Shares hereunder on the First Closing Date and the
aggregate number of Shares which such defaulting Underwriter or Underwriters
agreed but failed to purchase does not exceed 10 percent of the total number of
Shares which the Underwriters are obligated to purchase on the First Closing
Date, the Representatives may make arrangements satisfactory to the Company for
the purchase of such Shares by other persons, including any of the Underwriters,
but if no such arrangements are made by such date the nondefaulting Underwriters
shall be obligated severally, in proportion to their respective commitments
hereunder, to purchase the Shares which such defaulting Underwriters agreed but
failed to purchase on such 

                                         -26-

<PAGE>


date.  If any Underwriter or Underwriters so default and the aggregate number 
of Shares with respect to which such default or defaults occur is more than 
the above percentage and arrangements satisfactory to the Representatives and 
the Company for the purchase of such Shares by other persons are not made 
within 36 hours after such default, this Agreement will terminate without 
liability on the part of any nondefaulting Underwriter or the Company, except 
for the expenses to be paid by the Company pursuant to Section 6 hereof and 
except to the extent provided in Section 10 hereof.

     In the event that Shares to which a default relates are to be purchased by
the nondefaulting Underwriters or by another party or parties, the
Representatives or the Company shall have the right to postpone the First
Closing Date for not more than seven business days in order that the necessary
changes in the Registration Statement, Prospectus and any other documents, as
well as any other arrangements, may be effected.  As used in this Agreement, the
term "Underwriter" includes any person substituted for an Underwriter under this
Section.  Nothing herein will relieve a defaulting Underwriter from liability
for its default.

     SECTION 12.    EFFECTIVE DATE.  This Agreement shall become effective
immediately as to Sections 6, 8, 10 and 13 and as to all other provisions at
10:00 A.M., Chicago Time, on the day following the date upon which the Pricing
Agreement is executed and delivered, unless such a day is a Saturday, Sunday or
holiday (and in that event this Agreement shall become effective at such hour on
the business day next succeeding such Saturday, Sunday or holiday); but this
Agreement shall nevertheless become effective at such earlier time after the
Pricing Agreement is executed and delivered as you may determine on and by
notice to the Company or by release of any Shares for sale to the public.  For
the purposes of this Section, the Shares shall be deemed to have been so
released upon the release for publication of any newspaper advertisement
relating to the Shares or upon the release by you of telegrams (i) advising
Underwriters that the Shares are released for public offering, or (ii) offering
the Shares for sale to securities dealers, whichever may occur first.

     SECTION 13.    TERMINATION.  Without limiting the right to terminate this
Agreement pursuant to any other provision hereof:

          (a)  This Agreement may be terminated by the Company by notice to you
     or by you by notice to the Company at any time prior to the time this
     Agreement shall become effective as to all its provisions, and any such
     termination shall be without liability on the part of the Company to any
     Underwriter (except for the expenses to be paid or reimbursed pursuant to
     Section 6 hereof and except to the extent provided in Section 10 hereof) or
     of any Underwriter to the Company.

          (b)  This Agreement may also be terminated by you prior to the First
     Closing Date, and the option referred to in Section 4, if exercised, may be
     cancelled at any time prior to the Second Closing Date, if (i) trading in
     securities on the New York Stock Exchange shall have been suspended or
     minimum prices shall have been established on such exchange, or (ii) a
     banking moratorium shall have been declared by Illinois, New York, or
     United States authorities, or (iii) there shall have been


                                     -27-

<PAGE>


     any change in financial markets or in political, economic or financial 
     conditions which, in the opinion of the Representatives, either renders 
     it impracticable or inadvisable to proceed with the offering and sale of
     the Shares on the terms set forth in the Prospectus or materially and 
     adversely affects the market for the Shares, or (iv) there shall have been
     an outbreak of major armed hostilities between the United States and any 
     foreign power which in the opinion of the Representatives makes it 
     impractical or inadvisable to offer or sell the Shares.  Any termination 
     pursuant to this paragraph (b) shall be without liability on the part of 
     any Underwriter to the Company or on the part of the Company to any 
     Underwriter (except for expenses to be paid or reimbursed pursuant to 
     Section 6 hereof and except to the extent provided in Section 10 hereof).

     SECTION 14.    REPRESENTATIONS AND INDEMNITIES TO SURVIVE DELIVERY.  The
respective indemnities, agreements, representations, warranties and other
statements of the Company, of its officers and of the several Underwriters set
forth in or made pursuant to this Agreement will remain in full force and
effect, regardless of any investigation made by or on behalf of any Underwriter
or the Company or any of its or their partners, principals, members, officers or
directors or any controlling person, as the case may be, and will survive
delivery of and payment for the Shares sold hereunder.

     SECTION 15.    NOTICES.  All communications hereunder will be in writing
and, if sent to the Underwriters will be mailed, delivered or telegraphed and
confirmed to you c/o William Blair & Company, L.L.C., 222 West Adams Street,
Chicago, Illinois 60606, with a copy to Kenneth L. Guernsey, Cooley Godward LLP,
One Maritime Plaza, 20th Floor, San Francisco, California 94111; and if sent to
the Company will be mailed, delivered or telegraphed and confirmed to the
Company at its corporate headquarters with a copy to Alan K. Austin, Wilson
Sonsini Goodrich & Rosati, 650 Page Mill Road, Palo Alto, California, 94304.

     SECTION 16.    SUCCESSORS.  This Agreement and the Pricing Agreement will
inure to the benefit of and be binding upon the parties hereto and their
respective successors, personal representatives and assigns, and to the benefit
of the officers and directors and controlling persons referred to in Section 10,
and no other person will have any right or obligation hereunder.  The term
"successors" shall not include any purchaser of the Shares as such from any of
the Underwriters merely by reason of such purchase.

     SECTION 17.    REPRESENTATION OF UNDERWRITERS.  You will act as
Representatives for the several Underwriters in connection with this financing,
and any action under or in respect of this Agreement taken by you will be
binding upon all the Underwriters.

     SECTION 18.    PARTIAL UNENFORCEABILITY.  If any section, paragraph or
provision of this Agreement is for any reason determined to be invalid or
unenforceable, such determination shall not affect the validity or
enforceability of any other section, paragraph or provision hereof.

     SECTION 19.    APPLICABLE LAW.  This Agreement and the Pricing Agreement
shall be governed by and construed in accordance with the laws of the State of
Illinois.

                                       -28-

<PAGE>

     If the foregoing is in accordance with your understanding of our agreement,
kindly sign and return to us the enclosed duplicates hereof, whereupon it will
become a binding agreement among the Company and the several Underwriters
including you, all in accordance with its terms.

                                                  Very truly yours,

                                                  PROBUSINESS SERVICES, INC.

                                                  By   
                       
                                                        Thomas H. Sinton
                                                        Chief Executive Officer

The foregoing Agreement is hereby 
confirmed and accepted as of the date first
above written.
WILLIAM BLAIR & COMPANY, L.L.C.
BANCAMERICA ROBERTSON STEPHENS
SG COWEN SECURITIES CORPORATION 

Acting as Representatives of the several 
Underwriters named in Schedule A.


By William Blair & Company, L.L.C.


By   
   -------------------------------------------



                                         -29-

<PAGE>


                                      SCHEDULE A


                                                 Number of Firm Shares to be 
Underwriter                                      Purchased
- -----------                                      ----------------------------

William Blair & Company, L.L.C . . . . . . . . 

BancAmerica Robertson Stephen. . . . . . . . . 

SG Cowen Securities Corporatio . . . . . . . . 




                                                 -----------------------------

            TOTAL. . . . . . . . . . . . . . .
                                                 -----------------------------
                                                 -----------------------------


<PAGE>

                                  SCHEDULE B

                     Comfort Letter of Ernst & Young, LLP

     (1)  They are independent public accountants with respect to the Company
and its subsidiaries within the meaning of the 1933 Act.

     (2)  In their opinion the consolidated financial statements and schedules
of the Company and its subsidiaries included in the Registration Statement and
the consolidated financial statements of the Company from which the information
presented under the caption "Selected Consolidated Financial Data" has been
derived which are stated therein to have been examined by them comply as to form
in all material respects with the applicable accounting requirements of the 1933
Act.

     (3)  On the basis of specified procedures (but not an examination in
accordance with generally accepted auditing standards), including inquiries of
certain officers of the Company and its subsidiaries responsible for financial
and accounting matters as to transactions and events subsequent to ____________,
1998, a reading of minutes of meetings of the stockholders and directors of the
Company and its subsidiaries since ____________, 1998, a reading of the latest
available interim unaudited consolidated financial statements of the Company and
its subsidiaries (with an indication of the date thereof) and other procedures
as specified in such letter, nothing came to their attention which caused them
to believe that (i) the unaudited consolidated financial statements of the
Company and its subsidiaries included in the Registration Statement do not
comply as to form in all material respects with the applicable accounting
requirements of the 1933 Act or that such unaudited financial statements are not
fairly presented in accordance with generally accepted accounting principles
applied on a basis substantially consistent with that of the audited financial
statements included in the Registration Statement, and (ii) at a specified date
not more than five days prior to the date thereof in the case of the first
letter and not more than two business days prior to the date thereof in the case
of the second and third letters, there was any change in the capital stock or
long-term debt or short-term debt (other than normal payments) of the Company
and its subsidiaries on a consolidated basis or any decrease in consolidated net
current assets or consolidated stockholders' equity as compared with amounts
shown on the latest unaudited balance sheet of the Company included in the
Registration Statement or for the period from the date of such balance sheet to
a date not more than five days prior to the date thereof in the case of the
first letter and not more than two business days prior to the date thereof in
the case of the second and third letters, there were any decreases, as compared
with the corresponding period of the prior year, in consolidated net sales,
consolidated income before income taxes or in the total or per share amounts of
consolidated net income except, in all instances, for changes or decreases which
the Prospectus discloses have occurred or may occur or which are set forth in
such letter.

     (4)  They have carried out specified procedures, which have been agreed to
by the Representatives, with respect to certain information in the Prospectus
specified by the Representatives, and on 

<PAGE>

the basis of such procedures, they have found such information to be in 
agreement with the general accounting records of the Company and its 
subsidiaries.

                                      -32-

<PAGE>

                                                                     EXHIBIT A

                           PROBUSINESS SERVICES, INC.

                      ____________ Shares Common Stock (2)












- ---------------------
(2)Plus an option to acquire up to _______ additional shares to cover 
overallotments.

<PAGE>

                               PRICING AGREEMENT

                                                            ____________, 1998

William Blair & Company, L.L.C.
BancAmerica Robertson Stephens
SG Cowen Securities Corporation
     As Representatives of the Several
     Underwriters
c/o William Blair & Company, L.L.C.
222 West Adams Street
Chicago, Illinois  60606

Ladies and Gentlemen:

Reference is made to the Underwriting Agreement dated ____________, 1998 (the
"UNDERWRITING AGREEMENT") relating to the sale by the Company and the purchase
by the several Underwriters for whom William Blair & Company, L.L.C.,
BancAmerica Robertson Stephens and SG Cowen Securities Corporation are acting as
representatives (the "REPRESENTATIVES"), of the above Shares.  All terms herein
shall have the definitions contained in the Underwriting Agreement except as
otherwise defined herein.  

     Pursuant to Section 4 of the Underwriting Agreement, the Company agrees
with the Representatives as follows:

     1.   The initial public offering price per share for the Shares shall be
$__________.

     2.   The purchase price per share for the Shares to be paid by the several
Underwriters shall be $__________, being an amount equal to the initial public
offering price set forth above less $__________ per share.

     Schedule A is amended as follows:




     If the foregoing is in accordance with your understanding of our agreement,
kindly sign and return to us the enclosed duplicates hereof, whereupon it will
become a binding agreement among the Company and the several Underwriters,
including you, all in accordance with its terms.

                                      -34-

<PAGE>

                                           Very truly yours,

                                           PROBUSINESS SERVICES, INC.

                                           By

                                                 Chief Executive Officer

The foregoing Agreement is hereby 
confirmed and accepted as of the date first
above written.

WILLIAM BLAIR & COMPANY, L.L.C.
BANCAMERICA ROBERTSON STEPHENS
SG COWEN SECURITIES CORPORATION

Acting as Representatives of the several 
Underwriters.

By William Blair & Company, L.L.C.

By
   --------------------------------------
                Principal

                                      -35-



<PAGE>
                                                                    EXHIBIT 23.1
 
                   CONSENT AND REPORT OF INDEPENDENT AUDITORS
 
    We consent to the reference to our firm under the caption "Experts" and to
the use of our report dated July 23, 1998, in the Registration Statement (Form
S-1 No. 333-        ) and related Prospectus of ProBusiness Services, Inc. for
the registration of shares of its common stock.
 
    Our audits also included the financial statement schedule of ProBusiness
Services, Inc. listed in Item 16(b). This schedule is the responsibility of the
Company's management. Our responsibility is to express an opinion based on our
audits. In our opinion, the financial statement schedule referred to above, when
considered in relation to the basic financial statements taken as a whole,
presents fairly in all material respects the information set forth therein.
 
                                          /s/ ERNST & YOUNG LLP
 
Walnut Creek, California
August 5, 1998

<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<RESTATED> 
<MULTIPLIER> 1,000
       
<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   12-MOS                   12-MOS                   12-MOS
<FISCAL-YEAR-END>                          JUN-30-1996             JUN-30-1997             JUN-30-1998
<PERIOD-START>                             JUL-01-1995             JUL-01-1996             JUL-01-1997
<PERIOD-END>                               JUN-30-1996             JUN-30-1997             JUN-30-1998
<CASH>                                               0                   5,047                  13,771
<SECURITIES>                                         0                       0                       0
<RECEIVABLES>                                        0                   2,476                   2,612
<ALLOWANCES>                                         0                     365                     420
<INVENTORY>                                          0                       0                       0
<CURRENT-ASSETS>                                     0                 185,792                 351,172
<PP&E>                                               0                  11,954                  21,411
<DEPRECIATION>                                       0                   4,331                   7,453
<TOTAL-ASSETS>                                       0                 200,435                 376,009
<CURRENT-LIABILITIES>                                0                 185,751                 347,849
<BONDS>                                              0                       0                       0
                                0                       0                       0
                                          0                       3                       0
<COMMON>                                             0                       2                      17
<OTHER-SE>                                           0                   3,864                  26,729
<TOTAL-LIABILITY-AND-EQUITY>                         0                 200,435                 376,009
<SALES>                                              0                       0                       0
<TOTAL-REVENUES>                                13,863                  27,374                  46,317
<CGS>                                                0                       0                       0
<TOTAL-COSTS>                                    6,435                  13,659                  23,859
<OTHER-EXPENSES>                                 9,410                  18,829                  29,170
<LOSS-PROVISION>                                     0                       0                       0
<INTEREST-EXPENSE>                                 473                   1,190                     557
<INCOME-PRETAX>                                (2,386)                 (6,245)                 (6,517)
<INCOME-TAX>                                         0                       0                       0
<INCOME-CONTINUING>                            (2,386)                 (6,245)                 (6,517)
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                                   (2,386)                 (6,245)                 (6,517)
<EPS-PRIMARY>                                   (4.91)                  (0.59)                   (.41)
<EPS-DILUTED>                                   (4.91)                  (0.59)                   (.41)
        

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