NML VARIABLE ANNUITY ACCOUNT A
485BPOS, 2000-03-27
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<PAGE>   1
                                                    Registration No. 333-72913

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549
                                    FORM N-4
                   REGISTRATION STATEMENT UNDER THE SECURITIES
                                 ACT OF 1933                     / /
                         Pre-Effective Amendment No.             / /
                      Post-Effective Amendment No. 2             /X/
                                                  ---
                                     and/or

                   REGISTRATION STATEMENT UNDER THE INVESTMENT
                             COMPANY ACT OF 1940                 / /
                                Amendment No.                    / /
                                             ---
                        (Check appropriate box or boxes.)
                         NML VARIABLE ANNUITY ACCOUNT A
- --------------------------------------------------------------------------------
                           (Exact Name of Registrant)
                 THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
- --------------------------------------------------------------------------------
                               (Name of Depositor)
     720 East Wisconsin Avenue, Milwaukee, Wisconsin             53202
- --------------------------------------------------------------------------------
(Address of Depositor's Principal Executive Offices)          (Zip Code)

Depositor's Telephone Number, including Area Code  414-271-1444
                                                  ---------------
     JOHN M. BREMER, Executive Vice President, General Counsel and Secretary
              720 East Wisconsin Avenue, Milwaukee, Wisconsin 53202
- --------------------------------------------------------------------------------
                     (Name and Address of Agent for Service)

It is proposed that this filing will become effective (check appropriate space)

                immediately upon filing pursuant to paragraph (b) of Rule 485
        ---
         X      on March 31, 2000 pursuant to paragraph (b) of Rule 485
        ---
                60 days after filing pursuant to paragraph (a)(1) of Rule 485
        ---
                on (DATE) pursuant to paragraph (a)(1) of Rule 485
        ---
                this post-effective amendment designates a new effective date
        ---     for a previously filed post-effective amendment.


<PAGE>   2


                         NML VARIABLE ANNUITY ACCOUNT A


                              CROSS-REFERENCE SHEET

<TABLE>
<CAPTION>

N-4, Part A                                                   Heading in
Item                                                          Prospectus
- -----------                                                   ----------
<S>                                                         <C>
      1 ..................................................    Cover Page
      2 ..................................................    Index of Special Terms
      3 ..................................................    Expense Table
      4 ..................................................    Accumulation Unit Values, Financial Statements
      5 ..................................................    The Company, NML Variable Annuity Account A, The Funds
      6 ..................................................    Deductions, Distribution of the Contracts
      7 ..................................................    The Contracts, Owners of the Contracts, Application of Purchase
                                                              Payments, Transfers Between Divisions and Payment Plans, Substitution
                                                              and Change
      8 ..................................................    Variable Payment Plans, Description of Payment Plans, Amount of
                                                              Annuity Payments, Maturity Benefit, Assumed Investment Rate,
                                                              Transfers Between Divisions and Payment Plans
      9 ..................................................    Death Benefit
     10 ..................................................    Amount and Frequency, Application of Purchase Payments, Net
                                                              Investment Factor, Distribution of the Contracts
     11 ..................................................    Withdrawal Amount, Deferment of Benefit Payments, Right to Examine
                                                              Contract
     12 ..................................................    Federal Income Taxes
     13 ..................................................    Not Applicable
     14 ..................................................    Table of Contents for Statement of Additional Information

- ------------------------------------------------------------------------------------------------------------------------------------
<CAPTION>

N-4, Part B                                                   Heading in Statement
Item                                                          of Additional Information
- -----------                                                   -------------------------

<S>                                                         <C>
     15 ..................................................    Cover Page
     16 ..................................................    Table of Contents
     17 ..................................................    Not Applicable
     18 ..................................................    Experts
     19 ..................................................    Not Applicable
     20 ..................................................    Distribution of the Contracts
     21 ..................................................    Not Applicable
     22 ..................................................    Determination of Annuity Payments
     23 ..................................................    Financial Statements
</TABLE>


<PAGE>   3
PROSPECTUSES


March 31, 2000

[NORTHWESTERN MUTUAL LIFE(R) LOGO]

The Quiet Company(R)


                NML VARIABLE ANNUITY ACCOUNT A

                     Individual Variable Annuity Contracts for Retirement

                     Plans of Self-Employed Persons and Their Employees













                                     [PHOTO]















Northwestern Mutual Series Fund, Inc. and
Russell Insurance Funds

The Northwestern Mutual
Life Insurance Company
720 East Wisconsin Avenue
Milwaukee, Wisconsin 53202
(414) 271-1444


<PAGE>   4


[NORTHWESTERN MUTUAL LIFE(R) LOGO]



                                                                  March 31, 2000

PROFILE OF THE VARIABLE ANNUITY CONTRACT
This Profile is a summary of some of the more important points that you should
consider and know before purchasing the Contract. We describe the Contract more
fully in the prospectus which accompanies this Profile. Please read the
prospectus carefully.

1. THE ANNUITY CONTRACT The Contract provides retirement annuity benefits for
self-employed individuals (and their eligible employees). The Contract will
invest on a tax-deferred basis in your choice of sixteen investment portfolios.
The Contract also allows investment on a fixed basis in a guaranteed account.

The Contract is intended for retirement savings or other long-term investment
purposes. The Contract provides for a death benefit during the years when funds
are being accumulated and for a variety of income options following retirement.

The sixteen investment portfolios are listed in Section 4 below. These
portfolios bear varying amounts of investment risk. Those with more risk are
designed to produce a better long-term return than those with less risk. But
this is not guaranteed. You can also lose your money.

The amounts you invest on a fixed basis earn interest at a rate we declare from
time to time. We guarantee principal and we guarantee the interest rate for each
amount for at least one year.

You may invest in any or all of the sixteen investment portfolios. You may
move money among these portfolios without charge up to 12 times per year. After
that, a charge of $25 may apply. Transfers of amounts invested on a fixed basis
are subject to restrictions.

During the years when funds are being paid into your Contract, known as the
accumulation phase, the earnings accumulate on a tax-deferred basis. The
earnings are taxed as income if you make a withdrawal. The income phase begins
when you start receiving annuity payments from your Contract, usually at
retirement. Monthly annuity payments begin on the date you select.

The amount you accumulate in your Contract, including the results of
investment performance, will determine the amount of your monthly annuity
payments.

2. ANNUITY PAYMENTS If you decide to begin receiving monthly annuity payments
from your Contract, you may choose one of three payment plans: (1) monthly
payments for a specified period of five to thirty years, as you select, (2)
monthly payments for your life (assuming you are the annuitant), and you may
choose to have payments continue to your beneficiary for the balance of ten or
twenty years if you die sooner; or (3) monthly payments for your life and for
the life of another person (usually your spouse) selected by you. After you
begin receiving monthly annuity payments you cannot change your selection if the
payments depend on your life or the life of another.

These payment plans are available to you on a variable or fixed basis. Variable
means that the amount accumulated in your Contract will continue to be invested
in one or more of the sixteen investment portfolios as you choose. Your monthly
annuity payments will vary up or down to reflect continuing investment
performance. Or you may choose a fixed annuity payment plan which guarantees the
amount you will receive each month.


3. PURCHASE We offer Front Load and Back Load Contracts, as briefly described in
Section 5. You may make purchase payments of $25 or more as you accumulate funds
in your Contract. For the Front Load Contract the minimum initial purchase
payment is $10,000. Your Northwestern Mutual agent will help you complete a
Contract application form.


4. INVESTMENT CHOICES You may invest in any or all of the following investment
portfolios. All of these are described in the attached prospectuses for
Northwestern Mutual Series Fund, Inc. and the Russell Insurance Funds:

Northwestern Mutual Series Fund, Inc.

     1.  Small Cap Growth Stock Portfolio
     2.  Aggressive Growth Stock Portfolio
     3.  International Equity Portfolio
     4.  Index 400 Stock Portfolio
     5.  Growth Stock Portfolio
     6.  Growth and Income Stock Portfolio
     7.  Index 500 Stock Portfolio
     8.  Balanced Portfolio
     9.  High Yield Bond Portfolio
     10. Select Bond Portfolio
     11. Money Market Portfolio
         Russell Insurance Funds
     1.  Multi-Style Equity Fund
     2.  Aggressive Equity Fund
     3.  Non-U.S. Fund
     4.  Real Estate Securities Fund
     5.  Core Bond Fund
You may also invest all or part of your funds on a fixed basis (the Guaranteed
Interest Fund).


                                   PROFILE-i
<PAGE>   5


5. EXPENSES The Contract has insurance and investment features, and there are
costs related to them. For the Front Load Contract we deduct a sales load of
4.5% from your purchase payments. The percentage is lower when cumulative
purchase payments exceed $100,000. For the Back Load Contract there is no sales
load deducted from purchase payments but a withdrawal charge of 0% to 6%
applies, depending on the length of time the money you withdraw has been in the
Contract and the size of your Contract.

Each year we deduct a $30 Contract fee. Currently this fee is waived if the
value of your Contract is $25,000 or more.


We also deduct mortality and expense risk charges for the guarantees associated
with your Contract. These charges are at the annual rate of 0.50% for the Front
Load Contract. They begin at 1.25% for the Back Load Contract and are reduced to
0.50% for purchase payments that are no longer subject to withdrawal charges in
Contracts with a value of $25,000 or more. We may increase the charges to a
maximum rate of 0.75% for the Front Load Contract and 1.50% for the Back Load
Contract. We will not increase the charges for at least five years from the date
of the prospectus.

The portfolios also bear investment charges that range from an annual rate of
0.20% to 1.30% of the average daily value of the portfolio, depending on the
investment portfolio you select. The following charts are designed to help you
understand the charges for the Front Load and Back Load Contracts. The first
three columns show the annual expenses as a percentage of assets including the
insurance charges, the portfolio charges and the total charges. Portfolio
expenses are based on 1999 expenses for the portfolios. Expenses for the
portfolios reflect fee waivers and expense reimbursements. The last two columns
show you examples of the charges, in dollars, you would pay. The examples
reflect the impact of the asset based charges, any sales loads or withdrawals
that would apply, and the $30 Contract fee calculated by dividing the annual
Contract fees collected by the average assets of the sub-account. The examples
assume that you invested $1,000 in a Contract which earns 5% annually and that
you withdraw your money at the end of year one, and at the end of year ten. Both
of these examples, for both Contracts, reflect aggregate charges on a cumulative
basis to the end of the 1 or 10-year period.


For more detailed information, see the Expense Table which begins on page 3 of
the attached prospectus for the Contracts.


<TABLE>
<CAPTION>

                                                                     EXPENSES
============================================================================================================================
FRONT LOAD CONTRACT                      ANNUAL EXPENSES AS A PERCENTAGE OF ASSETS
                                                                                             EXAMPLES: *
                                               Total Annual       Total Annual     Total     Total Annual Charges At End of
                                            Insurance Charges      Portfolio      Annual
Portfolio                                                           Charges      Expenses    1 Year        10 Years
============================================================================================================================
<S>                                     <C>                        <C>          <C>           <C>            <C>
Northwestern Mutual Series Fund, Inc.
  Small Cap Growth Stock                  0.52% (0.50% + 0.02%)       1.00%         1.52%        $60            $236
  Aggressive Growth Stock                 0.52% (0.50% + 0.02%)       0.51%         1.03%        $55            $181
  International Equity                    0.52% (0.50% + 0.02%)       0.74%         1.26%        $57            $206
  Index 400 Stock                         0.52% (0.50% + 0.02%)       0.35%         0.87%        $53            $174
  Growth Stock                            0.52% (0.50% + 0.02%)       0.43%         0.95%        $54            $172
  Growth and Income Stock                 0.52% (0.50% + 0.02%)       0.57%         1.09%        $56            $187
  Index 500 Stock                         0.52% (0.50% + 0.02%)       0.20%         0.72%        $52            $146
  Balanced                                0.52% (0.50% + 0.02%)       0.30%         0.82%        $53            $158
  High Yield Bond                         0.52% (0.50% + 0.02%)       0.50%         1.02%        $55            $180
  Select Bond                             0.52% (0.50% + 0.02%)       0.30%         0.82%        $53            $158
  Money Market                            0.52% (0.50% + 0.02%)       0.30%         0.82%        $53            $158
Russell Insurance Funds
  Multi-Style Equity                      0.52% (0.50% + 0.02%)       0.92%         1.44%        $59            $228
  Aggressive Equity                       0.52% (0.50% + 0.02%)       1.25%         1.77%        $62            $267
  Non-U.S.                                0.52% (0.50% + 0.02%)       1.30%         1.82%        $63            $282
  Real Estate Securities                  0.52% (0.50% + 0.02%)       1.15%         1.67%        $61            $248
  Core Bond                               0.52% (0.50% + 0.02%)       0.80%         1.32%        $58            $218
- ----------------------------------------------------------------------------------------------------------------------------
</TABLE>

*TOTAL ANNUAL INSURANCE CHARGES INCLUDE THE INSURANCE CHARGES OF 0.50% PLUS
0.02% OF THE ASSETS TO REFLECT THE $30 CONTRACT FEE, BASED ON ACTUAL CONTRACT
FEES COLLECTED DIVIDED BY AVERAGE ASSETS OF THE SUB-ACCOUNT. THE ACTUAL IMPACT
OF THE CONTRACT FEE MAY BE GREATER OR LESS THAN 0.02%, DEPENDING UPON THE VALUE
OF YOUR CONTRACT. WE MAY INCREASE THE INSURANCE CHARGES TO A MAXIMUM RATE OF
0.75%. WE WILL NOT INCREASE THE CHARGES FOR AT LEAST FIVE YEARS FROM THE DATE OF
THE PROSPECTUS.


NOTE: THE MINIMUM INITIAL PURCHASE PAYMENT FOR A FRONT LOAD CONTRACT IS $10,000.
THE NUMBERS ABOVE MUST BE MULTIPLIED BY 10 TO FIND THE EXPENSES FOR A FRONT LOAD
CONTRACT OF MINIMUM SIZE.


                                   PROFILE-ii
<PAGE>   6


[NORTHWESTERN MUTUAL LIFE(R) LOGO]


<TABLE>
<CAPTION>

============================================================================================================================
BACK LOAD CONTRACT                       ANNUAL EXPENSES AS A PERCENTAGE OF ASSETS
                                                                   Total                      EXAMPLES: **
                                                Total Annual                                  Total Annual Charges At End
                                                                     Annual        Total      of
                                             Insurance Charges     Portfolio      Annual
Portfolio                                                           Charges      Expenses     1 Year          10 Years
============================================================================================================================
<S>                                      <C>                        <C>          <C>           <C>            <C>
Northwestern Mutual Series Fund, Inc.
  Small Cap Growth Stock                   1.46% (1.25% + 0.21%)       1.00%       2.46%            $ 85          $297
  Aggressive Growth Stock                  1.46% (1.25% + 0.21%)       0.51%       1.97%            $ 80          $245
  International Equity                     1.46% (1.25% + 0.21%)       0.74%       2.20%            $ 82          $268
  Index 400 Stock                          1.46% (1.25% + 0.21%)       0.35%       1.81%            $ 76          $237
  Growth Stock                             1.46% (1.25% + 0.21%)       0.43%       1.89%            $ 79          $237
  Growth and Income Stock                  1.46% (1.25% + 0.21%)       0.57%       2.03%            $ 81          $251
  Index 500 Stock                          1.46% (1.25% + 0.21%)       0.20%       1.66%            $ 77          $212
  Balanced                                 1.46% (1.25% + 0.21%)       0.30%       1.76%            $ 78          $223
  High Yield Bond                          1.46% (1.25% + 0.21%)       0.50%       1.96%            $ 80          $244
  Select Bond                              1.46% (1.25% + 0.21%)       0.30%       1.76%            $ 78          $223
  Money Market                             1.46% (1.25% + 0.21%)       0.30%       1.76%            $ 78          $223
Russell Insurance Funds
  Multi-Style Equity                       1.46% (1.25% + 0.21%)       0.92%       2.38%            $ 84          $290
  Aggressive Equity                        1.46% (1.25% + 0.21%)       1.25%       2.71%            $ 87          $326
  Non-U.S.                                 1.46% (1.25% + 0.21%)       1.30%       2.76%            $ 88          $341
  Real Estate Securities                   1.46% (1.25% + 0.21%)       1.15%       2.61%            $ 86          $309
  Core Bond                                1.46% (1.25% + 0.21%)       0.80%       2.26%            $ 83          $280
- ----------------------------------------------------------------------------------------------------------------------------
</TABLE>

**TOTAL ANNUAL INSURANCE CHARGES INCLUDE THE INSURANCE CHARGES OF 1.25% PLUS
0.21% OF THE ASSETS TO REFLECT THE $30 CONTRACT FEE, BASED ON ACTUAL CONTRACT
FEES COLLECTED DIVIDED BY AVERAGE ASSETS OF THE SUB-ACCOUNT. THE ACTUAL IMPACT
OF THE CONTRACT FEE MAY BE GREATER OR LESS THAN 0.21%, DEPENDING UPON THE VALUE
OF YOUR CONTRACT. WE MAY INCREASE THE INSURANCE CHARGES TO A MAXIMUM RATE OF
1.50%. WE WILL NOT INCREASE THE CHARGES FOR AT LEAST FIVE YEARS FROM THE DATE OF
THE PROSPECTUS.


6. TAXES As a general rule, earnings on your Contract are not taxed until they
are withdrawn or taken as monthly annuity payments. A 10% federal tax penalty
may apply if you make withdrawals from the Contract before the employee reaches
age 59 1/2.

7. ACCESS TO YOUR MONEY You may take money out of your Contract at any time
before monthly annuity payments begin. For the Front Load Contract there is no
charge for withdrawals. For the Back Load Contract there is a withdrawal charge
of 6% or less, depending on how much money has been paid into the Contract and
how long it has been held there. Each purchase payment has its own withdrawal
charge period. When you make a withdrawal, we use the amounts that produce the
lowest withdrawal charge. After the first year, 10% of the Contract value on the
prior anniversary may be withdrawn without a withdrawal charge if the Contract
value is at least $10,000. For both Front Load and Back Load Contracts, you may
also have to pay income tax and a tax penalty on amounts you take out.


8. PERFORMANCE The value of your Contract will vary up or down reflecting the
performance of the investment portfolios you select. The chart below shows total
returns for each of the investment portfolios that was in operation, and used
with the Account, during the years shown. Performance is not shown for the
portfolios that have not been in operation for one calendar year. These numbers,
for the Front Load Contract and the Back Load Contract, reflect the asset-based
charges for mortality and expense risks, the annual Contract fees and investment
expenses for each portfolio. The numbers include the annual Contract fee in the
amount of 0.02% for the Front Load Contract and 0.21% for the Back Load
Contract. The numbers do not reflect deductions from purchase payments for the
Front Load Contract or any withdrawal charge for the Back Load Contract. Those
charges, if applied, would reduce the performance. Past performance does not
guarantee future results.






                                  PROFILE-iii
<PAGE>   7


[NORTHWESTERN MUTUAL LIFE(R) LOGO]


<TABLE>
<CAPTION>
                                                       PERFORMANCE
============================================================================================================================
FRONT LOAD CONTRACT
                                                                     CALENDAR YEAR
PORTFOLIO                     1999     1998      1997      1996     1995      1994      1993     1992      1991      1990
============================================================================================================================
<S>                         <C>      <C>       <C>       <C>     <C>        <C>       <C>      <C>       <C>       <C>
Northwestern Mutual Series
Fund, Inc.
  Aggressive Growth Stock     43.09     7.00     13.27     17.08   38.57       4.86     18.49    5.39      55.19      NA
  International Equity        22.26     4.27     11.70     20.38   13.98      -0.62      NA      NA         NA        NA
  Growth Stock                21.86    26.04     29.18     20.28   30.15       NA        NA      NA         NA        NA
  Growth and Income Stock      6.92    22.50     29.37     19.34   30.44       NA        NA      NA         NA        NA
  Index 500 Stock             20.33    28.06     32.51     22.11   36.54       0.67      9.20    6.70      28.89      NA
  Balanced                    10.66    18.26     20.89     12.86   25.74      -0.53      9.01    4.77      23.30     0.56
  High Yield Bond             -0.97    -2.35     15.25     19.15   16.17       NA        NA      NA         NA        NA
  Select Bond                 -1.54     6.52      8.90      2.77   18.48      -3.34      9.76    6.43      16.27     7.77
  Money Market                 4.56     4.88      4.93      4.74    5.28       3.52      2.32    2.80       5.14     7.47
============================================================================================================================
<CAPTION>

BACK LOAD CONTRACT
                                                                     CALENDAR YEAR
PORTFOLIO                     1999     1998      1997      1996     1995      1994      1993     1992      1991      1990
============================================================================================================================
<S>                         <C>      <C>       <C>       <C>     <C>        <C>       <C>      <C>       <C>       <C>
Northwestern Mutual Series
Fund, Inc.
  Aggressive Growth Stock     41.71     6.00     12.22     15.98    37.28     3.88      17.39    4.41      53.74      NA
  International Equity        21.12     3.28     10.66     19.25    12.92    -1.54       NA       NA        NA        NA
  Growth Stock                20.72    24.86     27.98     19.15    28.93      NA        NA       NA        NA        NA
  Growth and Income Stock      5.93    21.36     28.15     18.22    29.23      NA        NA       NA        NA        NA
  Index 500 Stock             19.16    26.86     31.27     20.96    35.27    -0.27       8.18    5.70      27.68      NA
  Balanced                     9.59    17.16     19.76     11.80    24.57    -1.46       7.99    3.79      22.14    -0.42
  High Yield Bond             -1.90    -3.26     14.18     18.03    15.09      NA        NA       NA        NA        NA
  Select Bond                 -2.46     5.52      7.88      1.81    17.38    -4.24       8.74    5.44      15.19     6.75
  Money Market                 3.58     3.90      3.95      3.75     4.29     2.55       1.36    1.84       4.16     6.47
- ----------------------------------------------------------------------------------------------------------------------------
</TABLE>

9. DEATH BENEFIT If you die before age 75, and before monthly annuity payments
begin, your beneficiary will receive a death benefit. The amount will be the
value of your Contract or, if greater, the amount you have paid in. We offer an
enhanced death benefit at extra cost. We increase the enhanced death benefit on
each Contract anniversary, up to age 80, if the Contract value has increased.
The death benefit may be adjusted, of course, for any withdrawals you have made.
The death benefit will be paid as a lump sum or your beneficiary may select a
monthly annuity payment plan, or the Contract may be continued in force with a
contingent annuitant.


10.  OTHER INFORMATION

FREE LOOK. If you return the Contract within ten days after you receive it (or
whatever period is required in your state), we will send your money back. There
is no charge for our expenses but the amount you receive may be more or less
than what you paid, based on actual investment experience following the date we
received your purchase payment.

AVOID PROBATE. In most cases, when you die, your beneficiary will receive the
full death benefit of your Contract without going through probate.

AUTOMATIC DOLLAR-COST AVERAGING. With our Dollar-Cost Averaging Plan, you can
arrange to have a regular amount of money ($100 minimum) automatically
transferred from the Money Market Portfolio into the portfolio or portfolios you
have chosen on a monthly or quarterly basis.

ELECTRONIC FUNDS TRANSFER (EFT). Another convenient way to invest using the
dollar-cost averaging approach is through our EFT Plan. These automatic
checkbook withdrawals allow you to add to your portfolio(s) on a regular monthly
basis through payments drawn directly on your checking account.

SYSTEMATIC WITHDRAWAL PLAN. You can arrange to have regular amounts of money
sent to you while your Contract is still in the accumulation phase. Our
Systematic Withdrawal Plan allows you to automatically redeem accumulation units


                                   PROFILE-iv
<PAGE>   8


[NORTHWESTERN MUTUAL LIFE(R) LOGO]

to generate monthly payments. Of course you may have to pay taxes on amounts you
receive.

AUTOMATIC REQUIRED MINIMUM DISTRIBUTIONS. You can arrange for annual required
minimum distributions to be sent to you automatically once you turn age 70 1/2.

PORTFOLIO REBALANCING. To help you maintain your asset allocation plan over time
we offer a rebalancing service. This will automatically readjust your current
investment option allocations, on a periodic basis, back to the allocation
percentages you have selected.

INTEREST SWEEPS. If you select this service we will automatically sweep or
transfer interest from the Guaranteed Interest Fund to any combination of
variable investment options. Interest earnings can be swept monthly, quarterly,
semi-annually or annually.

NML EXPRESS. 1-800-519-4NML (1-800-519-4665). Get up-to-date information about
your contract at your convenience with your contract number and your Personal
Identification Number (PIN). Call toll-free to review contract values and unit
values, transfer among portfolios, change the allocation and obtain fund
performance information.

INTERNET. For information about Northwestern Mutual, visit us on our Website.
Included are daily unit values, fund performance information and access to
current values for Contracts you own.

                           WWW.NORTHWESTERNMUTUAL.COM

11. INQUIRIES If you need more information, please contact us at:


THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY, 720 EAST WISCONSIN AVENUE,
MILWAUKEE, WISCONSIN 53202; 1-888-455-2232.




                                   PROFILE-v
<PAGE>   9

P R O S P E C T U S


NML VARIABLE ANNUITY ACCOUNT A


This prospectus describes individual variable annuity contracts (the
"Contracts") offered by The Northwestern Mutual Life Insurance Company
("Northwestern Mutual") to provide retirement annuity benefits for self-employed
individuals (and their eligible employees) who adopt plans meeting the
requirements of Sections 401 or 403(a) of the Internal Revenue Code of 1986, as
amended. These plans, popularly called HR-10 Plans, afford certain federal
income tax benefits to employers and to employees and their beneficiaries.

We use NML Variable Annuity Account A (the "Account") to keep the money you
invest separate from our general assets. The money in the Account is invested in
the eleven portfolios of Northwestern Mutual Series Fund, Inc. and the five
Russell Insurance Funds. You select the Portfolios or Funds in which you want to
invest. Northwestern Mutual Series Fund, Inc.: Small Cap Growth Stock,
Aggressive Growth Stock, International Equity, Index 400 Stock, Growth Stock,
Growth and Income Stock, Index 500 Stock, Balanced, High Yield Bond, Select
Bond, Money Market. Russell Insurance Funds: Multi-Style Equity, Aggressive
Equity, Non-U.S., Real Estate Securities, Core Bond.


The Account has 16 Divisions that correspond to the 11 Portfolios and 5 Funds in
which you may invest. The Contracts also permit you to invest on a fixed basis,
at rates that we determine. This prospectus describes only the Account and the
variable provisions of the Contracts except where there are specific references
to the fixed provisions.

We offer two versions of the Contracts: Front Load Contracts and Back Load
Contracts. See the Expense table on page 3 and the Deductions section, beginning
on page 19.

This prospectus is a concise description of the information you should know
before you buy a Contract. We have filed additional information about the
Contracts with the Securities and Exchange Commission in a Statement of
Additional Information. We incorporate the Statement of Additional Information
into this prospectus by reference. We will send you the Statement of Additional
Information without charge if you write to The Northwestern Mutual Life
Insurance Company, 720 East Wisconsin Avenue, Milwaukee, Wisconsin, 53202, or
call us at Telephone Number (414) 271-1444. You will find the table of contents
for the Statement of Additional Information following page 22 of this
prospectus.

This prospectus is valid only when accompanied by the current prospectuses for
Northwestern Mutual Series Fund, Inc. and Russell Insurance Funds which are
attached to this prospectus. You should retain this prospectus for future
reference.

The Securities and Exchange Commission has not approved or disapproved these
securities or passed upon the adequacy of this prospectus. Any representation to
the contrary is a criminal offense.

The date of this prospectus and the Statement of Additional Information is March
31, 2000.


                                       1
<PAGE>   10


CONTENTS FOR THIS PROSPECTUS


<TABLE>
<CAPTION>
                                              PAGE
                                              ----
<S>                                          <C>
PROSPECTUS......................................1
    NML Variable Annuity Account A..............1
INDEX OF SPECIAL TERMS..........................3
EXPENSE TABLE...................................3
ACCUMULATION UNIT VALUES........................7
THE COMPANY....................................12
NML VARIABLE ANNUITY
   ACCOUNT A...................................12
THE FUNDS......................................12
THE CONTRACTS..................................13
    Purchase Payments Under the Contracts......13
      Amount and Frequency.....................13
      Application of Purchase Payments.........13
    Net Investment Factor......................14
    Benefits Provided Under the Contracts......14
      Withdrawal Amount........................14
      Death Benefit............................14
      Maturity Benefit.........................15
    Variable Payment Plans.....................15
      Description of Payment Plans.............15
      Amount of Annuity Payments...............15
      Assumed Investment Rate..................15
    Additional Information.....................16
      Transfers Between Divisions and
        Payment Plans..........................16
      Gender-Based Annuity Payment Rates.......16
      Owners of the Contracts..................16
      Deferment of Benefit Payments............16
      Dividends................................16
      Substitution and Change..................17
      Fixed Annuity Payment Plans..............17
      Financial Statements.....................17
THE GUARANTEED INTEREST FUND...................17
FEDERAL INCOME TAXES...........................18
    Contribution Limits........................18
    Taxation of Contract Benefits..............18
    Minimum Distribution Requirements..........18
    Taxation of Northwestern Mutual............19
DEDUCTIONS.....................................19
    Sales Load.................................19
    Mortality Rate and Expense Risk Charges....19
    Contract Fee...............................20
    Withdrawal Charge..........................20
    Enhanced Death Benefit Charge..............20
    Premium Taxes..............................20
    Expenses for the Portfolios and Funds......21
    Contracts Issued Prior to March 31, 2000...21
    Contracts Issued Prior to March 31, 1995...21
    Contracts Issued Prior to
      December 17, 1981........................21
    Dividends for Contracts Issued Prior to
      March 31, 2000...........................21
    Reduced Charges for Exchange
      Transactions.............................21

DISTRIBUTION OF THE CONTRACTS..................22
</TABLE>




THE TABLE OF CONTENTS FOR THE STATEMENT OF ADDITIONAL INFORMATION APPEARS ON THE
                   PAGE FOLLOWING PAGE 22 OF THIS PROSPECTUS.



                                       2
<PAGE>   11


INDEX OF SPECIAL TERMS
The following special terms used in this prospectus are discussed at the pages
indicated.


<TABLE>
<CAPTION>

TERM                                               PAGE    TERM                                             PAGE
- ----                                               ----    ----                                             ----
<S>                                               <C>    <C>                                               <C>
ACCUMULATION UNIT...................................13     ANNUITANT.........................................16
ANNUITY (or ANNUITY PAYMENTS).......................15     MATURITY DATE.....................................15
NET INVESTMENT FACTOR...............................14     OWNER.............................................16
PAYMENT PLANS.......................................15     WITHDRAWAL AMOUNT.................................14
================================================================================================================
<CAPTION>

EXPENSE TABLE
<S>                                          <C>           <C>                                             <C>
FRONT LOAD CONTRACT                                          ANNUAL EXPENSES OF THE ACCOUNT
TRANSACTION EXPENSES FOR CONTRACTOWNERS                       (AS A PERCENTAGE OF ASSETS)
Maximum Sales Load (as a percentage                          Current Mortality and Expense Risk Fees*.......0.50%
of purchase payments)..........................4.5%          Maximum Mortality and Expense Risk
Withdrawal Charge..............................None             Fees*.......................................0.75%
                                                             Other Expenses.................................None
                                                             Total Current Separate Account Annual
                                                                Expenses*...................................0.50%
                                                             Total Maximum Separate Account Annual
                                                                Expenses*...................................0.75%
                                                             ANNUAL CONTRACT FEE
                                                             $30; waived if the Contract Value equals or exceeds
                                                             $25,000
================================================================================================================
<CAPTION>

<S>                                          <C>           <C>                                             <C>
BACK LOAD CONTRACT                                           ANNUAL EXPENSES OF THE ACCOUNT
TRANSACTION EXPENSES FOR CONTRACTOWNERS                       (AS A PERCENTAGE OF ASSETS)
Sales Load (as a percentage of purchase                      Current Mortality and Expense Risk Fees*.......1.25%
payments)......................................None          Maximum Mortality and Expense Risk
Withdrawal Charge for Sales Expenses                            Fees*.......................................1.50%
(as a percentage of amounts paid)..............0%-6%         Other Expenses.................................None
                                                             Total Current Separate Account Annual
                                                                Expenses*...................................1.25%
                                                             Total Maximum Separate Account Annual
                                                                Expenses*...................................1.50%

                                                             ANNUAL CONTRACT FEE
                                                             $30; waived if the Contract Value equals or exceeds
                                                             $25,000

*WE GUARANTEE THE CURRENT MORTALITY AND EXPENSE RISK FEES FOR FIVE YEARS FROM
THE DATE OF THIS PROSPECTUS. THEREAFTER, WE RESERVE THE RIGHT TO INCREASE THE
MORTALITY AND EXPENSE RISK FEES TO A MAXIMUM ANNUAL RATE OF 0.75% FOR THE FRONT
LOAD CONTRACT AND 1.50% FOR THE BACK LOAD CONTRACT.
</TABLE>




                                       3
<PAGE>   12


<TABLE>
<CAPTION>

ANNUAL EXPENSES OF THE PORTFOLIOS AND FUNDS                                                   TOTAL ANNUAL
(AS A PERCENTAGE OF THE ASSETS)                                                                 EXPENSES
                                                      MANAGEMENT FEES         OTHER         (AFTER EXPENSE
                                                    (AFTER FEE WAIVER)       EXPENSES        REIMBURSEMENT)
                                                    ------------------       --------        --------------
<S>                                                    <C>                  <C>               <C>
Northwestern Mutual Series Fund, Inc.
   Small Cap Growth Stock*                                 0.79%              0.21%              1.00%
   Aggressive Growth Stock                                 0.51%              0.00%              0.51%
   International Equity                                    0.67%              0.07%              0.74%
   Index 400 Stock*                                        0.25%              0.10%              0.35%
   Growth Stock                                            0.43%              0.00%              0.43%
   Growth and Income Stock                                 0.57%              0.00%              0.57%
   Index 500 Stock                                         0.20%              0.00%              0.20%
   Balanced                                                0.30%              0.00%              0.30%
   High Yield Bond                                         0.49%              0.01%              0.50%
   Select Bond                                             0.30%              0.00%              0.30%
   Money Market                                            0.30%              0.00%              0.30%
Russell Insurance Funds*
   Multi-Style Equity                                      0.77%              0.15%              0.92%
   Aggressive Equity                                       0.86%              0.39%              1.25%
   Non-U.S.                                                0.75%              0.55%              1.30%
   Real Estate Securities                                  0.85%              0.30%              1.15%
   Core Bond                                               0.54%              0.26%              0.80%
==========================================================================================================
* FOR THE RUSSELL INSURANCE FUNDS (THE "FUND"), THE SMALL CAP GROWTH STOCK
PORTFOLIO AND THE INDEX 400 STOCK PORTFOLIO (THE "PORTFOLIOS"), THE ADVISER HAS
VOLUNTARILY AGREED TO WAIVE A PORTION OF THE MANAGEMENT FEE, UP TO THE FULL
AMOUNT OF THE FEE, EQUAL TO THE AMOUNT BY WHICH THE FUND'S AND PORTFOLIOS' TOTAL
OPERATING EXPENSES EXCEED THE AMOUNTS SHOWN ABOVE UNDER "TOTAL ANNUAL EXPENSES
(AFTER EXPENSE REIMBURSEMENT)". THE ADVISER HAS ALSO AGREED TO REIMBURSE THE
FUND AND PORTFOLIOS FOR ALL REMAINING EXPENSES AFTER FEE WAIVERS WHICH EXCEED
THE AMOUNTS SHOWN ABOVE UNDER THAT HEADING. ABSENT THE FEE WAIVER AND EXPENSE
REIMBURSEMENT, THE MANAGEMENT FEES AND TOTAL ANNUAL EXPENSES WOULD BE 0.78% AND
0.93% FOR THE MULTI-STYLE EQUITY FUND; 0.95% AND 1.34% FOR THE AGGRESSIVE EQUITY
FUND; 0.95% AND 1.50% FOR THE NON-U.S. FUND; 0.85% AND 1.15% FOR THE REAL ESTATE
SECURITIES FUND; 0.60% AND 0.86% FOR THE CORE BOND FUND; 0.79% AND 1.03% FOR THE
SMALL CAP GROWTH STOCK PORTFOLIO; AND 0.25% AND 0.46% FOR THE INDEX 400 STOCK
PORTFOLIO.
==========================================================================================================
</TABLE>


EXAMPLE

FRONT LOAD CONTRACT - You would pay the following expenses on each $1,000
investment, assuming 5% annual return:


<TABLE>
<CAPTION>

                                                      1 YEAR            3 YEARS             5 YEARS           10 YEARS
                                                      ------            -------             -------           --------
<S>                                                 <C>                <C>                <C>                 <C>
Northwestern Mutual Series Fund, Inc.
   Small Cap Growth Stock                              $60                $91                $125               $236
   Aggressive Growth Stock                             $55                $76                $ 99               $181
   International Equity                                $57                $83                $111               $206
   Index 400 Stock                                     $53                $74                $ 96               $174
   Growth Stock                                        $54                $74                $ 95               $172
   Growth and Income Stock                             $56                $78                $102               $187
   Index 500 Stock                                     $52                $67                $ 83               $146
   Balanced                                            $53                $70                $ 88               $158
   High Yield Bond                                     $55                $76                $ 99               $180
   Select Bond                                         $53                $70                $ 88               $158
   Money Market                                        $53                $70                $ 88               $158
Russell Insurance Funds
   Multi-Style Equity                                  $59                $89                $122               $228
   Aggressive Equity                                   $62                $100               $140               $267
   Non-U.S.                                            $63                $104               $147               $282
   Real Estate Securities                              $61                $95                $132               $248
   Core Bond                                           $58                $86                $117               $218
</TABLE>


NOTE: THE MINIMUM INITIAL PURCHASE PAYMENT FOR A FRONT-LOAD CONTRACT IS $10,000.
YOU MUST MULTIPLY THE NUMBERS ABOVE BY 10 TO FIND THE EXPENSES FOR A FRONT-LOAD
CONTRACT OF MINIMUM SIZE.



                                       4
<PAGE>   13
EXAMPLE

BACK LOAD CONTRACT - You would pay the following expenses on a $1,000
investment, assuming (1) 5% annual return and (2) surrender just prior to the
end of each time period:


<TABLE>
<CAPTION>

                                                      1 YEAR            3 YEARS          5 YEARS          10 YEARS
                                                      ------            -------          -------          --------
<S>                                                   <C>               <C>              <C>              <C>
Northwestern Mutual Series Fund, Inc.
- -------------------------------------
   Small Cap Growth Stock                              $ 85              $137             $173              $297
   Aggressive Growth Stock                             $ 80              $122             $147              $245
   International Equity                                $ 82              $129             $158              $268
   Index 400 Stock                                     $ 76              $117             $141              $237
   Growth Stock                                        $ 79              $120             $142              $237
   Growth and Income Stock                             $ 81              $124             $150              $251
   Index 500 Stock                                     $ 77              $113             $130              $212
   Balanced                                            $ 78              $116             $136              $223
   High Yield Bond                                     $ 80              $122             $146              $244
   Select Bond                                         $ 78              $116             $136              $223
   Money Market                                        $ 78              $116             $136              $223
Russell Insurance Funds
- -----------------------
   Multi-Style Equity                                  $ 84              $135             $169              $290
   Aggressive Equity                                   $ 87              $146             $187              $326
   Non-U.S.                                            $ 88              $150             $194              $341
   Real Estate Securities                              $ 86              $141             $179              $309
   Core Bond                                           $ 83              $132             $164              $280
</TABLE>



You would pay the following expenses on the same $1,000 investment, assuming no
surrender or annuitization:


<TABLE>
<CAPTION>

                                                        1 YEAR            3 YEARS        5 YEARS          10 YEARS
                                                        ------            -------        -------          --------
<S>                                                     <C>               <C>            <C>              <C>
Northwestern Mutual Series Fund, Inc.
- -------------------------------------
   Small Cap Growth Stock                                 $25               $77            $133             $297
   Aggressive Growth Stock                                $20               $62            $107             $245
   International Equity                                   $22               $69            $118             $268
   Index 400 Stock                                        $16               $57            $101             $237
   Growth Stock                                           $19               $60            $102             $237
   Growth and Income Stock                                $21               $64            $110             $251
   Index 500 Stock                                        $17               $53            $ 90             $212
   Balanced                                               $18               $56            $ 96             $223
   High Yield Bond                                        $20               $62            $106             $244
   Select Bond                                            $18               $56            $ 96             $223
   Money Market                                           $18               $56            $ 96             $223
Russell Insurance Funds
- -----------------------
   Multi-Style Equity                                     $24               $75            $129             $290
   Aggressive Equity                                      $27               $86            $147             $326
   Non-U.S.                                               $28               $90            $154             $341
   Real Estate Securities                                 $26               $81            $139             $309
   Core Bond                                              $23               $72            $124             $280
</TABLE>



The purpose of the table above is to assist a Contract Owner in understanding
the expenses paid by the Account and the Portfolios and Funds and borne by
investors in the Contracts. The sales load for a Front Load Contract depends on
the amount of cumulative purchase payments. For the Back Load Contract the
mortality and expense risk charge and the withdrawal charge depend on the length
of time funds have been held under the Contract and the amounts held. We
guarantee the current mortality and expense risk charges for five years from the
date of this prospectus. Thereafter, we reserve the right to increase the
mortality and expense risk charges to a maximum annual rate of 0.75% for the
Front Load Contract and 1.50% for the Back Load Contract. The table shows the
maximum current charges for both the mortality and expense risk charge and the
withdrawal charge for the first five years. The expenses for the ten years shown
in the table are the maximum expenses if we increase the mortality and expense
risk charge after five years. There is no withdrawal charge when a variable
payment plan is selected, but we may make a withdrawal charge in some
circumstances when a fixed payment plan is selected. See "Withdrawal Charge", p.
20. The $30 annual Contract fee is reflected as 0.02% for the Front Load
Contract and 0.21% for the Back Load


                                       5

<PAGE>   14



Contract based on the annual Contract fees collected divided by the average
assets of the Division. The Contracts provide for charges for transfers between
the Divisions of the Account and for premium taxes, but we are not currently
making such charges. See "Transfers Between Divisions and Payment Plans", p. 16
and "Deductions", p. 19, for additional information about expenses for the
Contracts. The expenses shown in the table for the Portfolios and Funds show the
annual expenses for each, as a percentage of their average net assets, based on
1999 operations for the Portfolios and their predecessors and the Funds.
Expenses for each of the Russell Insurance Funds reflect fee waivers and expense
reimbursements that the Funds' adviser has voluntarily agreed to make for the
year 2000. These may be changed at any time without notice. Absent the fee
waivers and expense reimbursements the expenses would be higher. See the
disclosure at the bottom of page 3. For additional information about expenses of
the Portfolios and Funds, see the prospectuses for Northwestern Mutual Series
Fund, Inc. and the Russell Insurance Funds attached to this prospectus.


The example should not be considered a representation of past or future
expenses. Actual expenses may be greater or less than those shown, subject to
the guarantees of the Contracts.

The tables on the following pages present the accumulation unit values for
Contracts issued prior to the date of this prospectus. The Contracts issued
prior to the date of this prospectus are different in certain material respects
from Contracts offered currently. The values shown below for Back Load Contracts
issued on or after December 17, 1981 and prior to March 31, 2000 are calculated
on the same basis as those for the Class B Accumulation Units for the Back Load
Contracts described in this prospectus.



















                                       6

<PAGE>   15





ACCUMULATION UNIT VALUES
CONTRACTS ISSUED ON OR AFTER MARCH 31, 1995 AND PRIOR TO MARCH 31, 2000

NORTHWESTERN MUTUAL SERIES FUND, INC.
- -------------------------------------
<TABLE>
<CAPTION>

                                                   FOR YEARS ENDED
                                                    DECEMBER 31                      FOR THE NINE
                                         -----------------------------------------   MONTHS ENDED
                                          1999        1998       1997      1996      DEC. 31, 1995
                                         ------      ------     ------    ------     -------------
<S>                                   <C>           <C>        <C>        <C>        <C>
     SMALL CAP GROWTH STOCK DIVISION
     Front Load Version
      Beginning of Period*               $1.000       --          --         --             --
      End of Period                      $1.856       --          --         --             --
     Back Load Version
      Beginning of Period*               $1.000       --          --         --             --
      End of Period                      $1.846       --          --         --             --
     Number of Units
     Outstanding, End of Period
      Front Load                        149,996       --          --         --             --
      Back Load                         481,140       --          --         --             --

     AGGRESSIVE GROWTH STOCK DIVISION
     Front Load Version
      Beginning of Period                $1.859       $1.735      $1.530       $1.305      $1.000
      End of Period                      $2.662       $1.859      $1.735       $1.530      $1.305
     Back Load Version
      Beginning of Period                $3.808       $3.585      $3.188       $2.743      $2.115
      End of Period                      $5.408       $3.808      $3.585       $3.188      $2.743
     Number of Units
     Outstanding, End of Period
      Front Load                      1,185,824    1,195,051       832,513    568,732     255,895
      Back Load                       3,585,337    3,703,653     2,962,218  1,734,023     407,729

     INTERNATIONAL EQUITY DIVISION
     Front Load Version
      Beginning of Period                $1.605       $1.537      $1.374       $1.140      $1.000
      End of Period                      $1.964       $1.605      $1.537       $1.374      $1.140
     Back Load Version
      Beginning of Period                $1.893       $1.829      $1.649       $1.380      $1.218
      End of Period                      $2.298       $1.893      $1.829       $1.649      $1.380
     Number of Units
     Outstanding, End of Period
      Front Load                        727,940      669,024       575,775    286,469      32,573
      Back Load                       3,063,127    3,028,502     2,488,184  1,281,128     374,986

     INDEX 400 STOCK DIVISION
     Front Load Version
      Beginning of Period*               $1.000          --          --      --              --
      End of Period                      $1.125          --          --      --              --
     Back Load Version
      Beginning of Period*               $1.000          --          --      --              --
      End of Period                      $1.119          --          --      --              --
     Number of Units
     Outstanding, End of Period
      Front Load                        162,971          --          --      --              --
      Back Load                         388,194          --          --      --              --

     GROWTH STOCK DIVISION
     Front Load Version
      Beginning of Period                $2.375       $1.883      $1.456       $1.209      $1.000
      End of Period                      $2.898       $2.375      $1.883       $1.456      $1.209
     Back Load Version
      Beginning of Period                $2.491       $1.991      $1.552       $1.300      $1.082
      End of Period                      $3.013       $2.491      $1.991       $1.552      $1.300
     Number of Units
     Outstanding, End of Period
      Front Load                        613,097       447,934      422,029    257,158     103,292
      Back Load                       3,381,484     2,761,432    1,870,296    922,390     227,218

     GROWTH AND INCOME STOCK DIVISION
     Front Load Version
      Beginning of Period                $2.271        $1.852     $1.430       $1.197      $1.000
      End of Period                      $2.431        $2.271     $1.852       $1.430      $1.197
     Back Load Version
      Beginning of Period                $2.382        $1.959     $1.525       $1.287      $1.083
      End of Period                      $2.528        $2.382     $1.959       $1.525      $1.287
     Number of Units
     Outstanding, End of Period
      Front Load                        757,434       736,836    540,977      208,323     114,414
      Back Load                       3,306,924     3,046,517  1,940,827    1,215,721     310,321

</TABLE>


<TABLE>
<CAPTION>

                                                   FOR YEARS ENDED
                                                   DECEMBER 31                       FOR THE NINE
                                         -----------------------------------------   MONTHS ENDED
                                          1999        1998       1997      1996      DEC. 31, 1995
                                         ------      ------     ------    ------     -------------
<S>                                   <C>         <C>        <C>        <C>          <C>
INDEX 500 STOCK DIVISION
Front Load Version
 Beginning of Period                     $2.597      $2.026     $1.527     $1.249        $1.000
 End of Period                           $3.128      $2.597     $2.026     $1.527        $1.249
Back Load Version
 Beginning of Period                     $4.037      $3.175     $2.414     $1.991        $1.604
 End of Period                           $4.820      $4.037     $3.175     $2.414        $1.991
Number of Units
Outstanding, End of Period
 Front Load                           1,247,611   1,057,935    690,248    454,096       278,235
 Back Load                            5,417,756   4,504,322  3,279,176  1,970,961       471,752

BALANCED DIVISION
Front Load Version
 Beginning of Period                     $1.912      $1.615     $1.334     $1.181        $1.000
 End of Period                           $2.118      $1.912     $1.615     $1.334        $1.181
Back Load Version
 Beginning of Period                     $6.771      $5.768     $4.806     $4.290        $3.655
 End of Period                           $7.436      $6.771     $5.768     $4.806        $4.290
Number of Units
Outstanding, End of Period
 Front Load                           1,800,477   1,768,955  1,296,330    786,271       164,302
 Back Load                            2,897,246   2,565,265  2,109,606  1,347,427       372,457

HIGH YIELD BOND DIVISION
Front Load Version
 Beginning of Period                     $1.496      $1.530     $1.326     $1.112        $1.000
 End of Period                           $1.483      $1.496     $1.530     $1.326        $1.112
Back Load Version
 Beginning of Period                     $1.546      $1.595     $1.394     $1.178        $1.067
 End of Period                           $1.520      $1.546     $1.595     $1.394        $1.178
Number of Units
Outstanding, End of Period
 Front Load                             380,690     400,132     95,718     55,625          --
 Back Load                            1,174,446   1,400,604    967,118    572,121       138,470

SELECT BOND DIVISION
Front Load Version
 Beginning of Period                     $1.350      $1.266     $1.161     $1.129        $1.000
 End of Period                           $1.331      $1.350     $1.266     $1.161        $1.129
Back Load Version
 Beginning of Period                     $7.088      $6.703     $6.201     $6.078        $5.419
 End of Period                           $6.929      $7.088     $6.703     $6.201        $6.078
Number of Units
Outstanding, End of Period
 Front Load                             214,565     159,609     72,941     38,713        26,732
 Back Load                              364,139     368,314    271,027    182,907        50,828

MONEY MARKET DIVISION
Front Load Version
 Beginning of Period                     $1.203      $1.146     $1.091     $1.040        $1.000
 End of Period                           $1.259      $1.203     $1.146     $1.091        $1.040
Back Load Version
 Beginning of Period                     $2.431      $2.335     $2.241     $2.156        $2.086
 End of Period                           $2.523      $2.431     $2.335     $2.241        $2.156
Number of Units
Outstanding, End of Period
 Front Load                           1,980,615   1,564,597  1,439,686  1,843,605       327,441
 Back Load                            1,892,502   1,515,128  1,081,227  1,123,081       379,473

</TABLE>

*  The initial investments in the Small Cap Growth Stock Division and Index
   400 Stock Division were made on April 30, 1999.
** The initial investment was made on April 30, 1999.



                                       7

<PAGE>   16


ACCUMULATION UNIT VALUES
(CONTINUED)

RUSSELL INSURANCE FUNDS
- -----------------------

<TABLE>
<CAPTION>

                                    FOR THE EIGHT MONTHS ENDED                                       FOR THE EIGHT MONTHS ENDED
                                    --------------------------                                       --------------------------
                                           DECEMBER 31                                                       DECEMBER 31
                                           -----------                                                       -----------
                                              1999                                                               1999
                                              ----                                                               ----
<S>                                 <C>                            <C>                                <C>
     MULTI-STYLE EQUITY DIVISION                                   REAL ESTATE SECURITIES DIVISION
     Front Load Version                                            Front Load Version
      Beginning of Period*                  $1.000                  Beginning of Period*                        $1.000
      End of Period                         $1.073                  End of Period                               $ .925
     Back Load Version                                             Back Load Version
      Beginning of Period*                  $1.000                  Beginning of Period*                        $1.000
      End of Period                         $1.067                  End of Period                               $ .920
     Number of Units                                               Number of Units
     Outstanding, End of Period                                    Outstanding, End of Period
      Front Load                            321,514                 Front Load                                   19,288
      Back Load                             535,268                 Back Load                                    88,176

     AGGRESSIVE EQUITY DIVISION                                    CORE BOND DIVISION
     Front Load Version                                            Front Load Version
      Beginning of Period*                  $1.000                  Beginning of Period*                        $1.000
      End of Period                         $1.106                  End of Period                               $ .989
     Back Load Version                                             Back Load Version
      Beginning of Period*                  $1.000                  Beginning of Period*                        $1.000
      End of Period                         $1.100                  End of Period                               $ .983
     Number of Units                                               Number of Units
     Outstanding, End of Period                                    Outstanding, End of Period
      Front Load                            87,678                  Front Load                                   26,817
      Back Load                             182,385                 Back Load                                    93,910

     NON-U.S. DIVISION
     Front Load Version
      Beginning of Period*                  $1.000
      End of Period                         $1.250
     Back Load Version
      Beginning of Period*                  $1.000
      End of Period                         $1.243
     Number of Units
     Outstanding, End of Period
      Front Load                            81,105
      Back Load                             205,407

</TABLE>


*The initial investment was made on April 30, 1999.













                                       8


<PAGE>   17



ACCUMULATION UNIT VALUES
CONTRACTS ISSUED AFTER DECEMBER 16, 1981 AND PRIOR TO MARCH 31, 1995

NORTHWESTERN MUTUAL SERIES FUND, INC.
- -------------------------------------

<TABLE>
<CAPTION>
                                                               FOR THE YEARS ENDED DECEMBER 31
                                            ---------------------------------------------------------------------

                                                 1999         1998         1997          1996          1995
                                                 ----         ----         ----          ----          ----
<S>                                           <C>           <C>          <C>           <C>          <C>
  SMALL CAP GROWTH STOCK DIVISION
    Beginning of Period*                         $1.000        --           --            --            --
    End of Period                                $1.846        --           --            --            --
  Number of Units
    Outstanding, End of Period                 1,898,627       --           --            --            --


  AGGRESSIVE GROWTH STOCK DIVISION
    Beginning of Period*                         $3.808       $3.585       $3.188        $2.743        $1.994
    End of Period                                $5.408       $3.808       $3.585        $3.188        $2.743
  Number of Units
    Outstanding, End of Period                 14,666,263   18,213,135   20,861,309    21,479,837   19,083,707


  INTERNATIONAL EQUITY DIVISION
    Beginning of Period**                        $1.893       $1.829       $1.649        $1.380        $1.220
    End of Period                                $2.298       $1.893       $1.829        $1.649        $1.380
  Number of Units
    Outstanding, End of Period                 15,307,814   19,261,448   22,910,908    22,132,206   21,338,267


  INDEX 400 STOCK DIVISION
    Beginning of Period*                         $1.000        --           --            --            --
    End of Period                                $1.119        --           --            --            --
  Number of Units
    Outstanding, End of Period                 1,241,398       --           --            --            --



  GROWTH STOCK DIVISION
    Beginning of Period+                          $2.491      $1.991       $1.552        $1.300        $1.006
    End of Period                                 $3.013      $2.491       $1.991        $1.552        $1.300
  Number of Units
    Outstanding, End of Period                  8,576,102   7,215,894     6,045,075     4,845,965    2,970,905



  GROWTH AND INCOME STOCK DIVISION
    Beginning of Period+                         $2.382       $1.959       $1.525        $1.287        $0.994
    End of Period                                $2.528       $2.382       $1.959        $1.525        $1.287
  Number of Units
    Outstanding, End of Period                  9,502,862  10,866,893     8,963,724     7,054,484    5,605,215



  INDEX 500 STOCK DIVISION
    Beginning of Period*                         $4.037       $3.175       $2.414        $1.991        $1.469
    End of Period                                $4.820       $4.037       $3.175        $2.414        $1.991
  Number of Units
    Outstanding, End of Period                 20,900,522   21,467,931   21,531,879    20,092,060   18,961,291



  BALANCED DIVISION
    Beginning of Period                          $6.771       $5.768       $4.806        $4.290        $3.436
    End of Period                                $7.436       $6.771       $5.768        $4.806        $4.290
  Number of Units
    Outstanding, End of Period                 35,440,432   40,487,926   44,638,127    48,457,793   52,575,295



  HIGH YIELD BOND DIVISION
    Beginning of Period+                         $1.546       $1.595       $1.394       $1.178         $1.022
    End of Period                                $1.520       $1.546       $1.595       $1.394         $1.178
  Number of Units
    Outstanding, End of Period                  2,904,325    3,974,656    3,770,055    2,456,295     1,609,770



  SELECT BOND DIVISION
    Beginning of Period                          $7.088       $6.703       $6.201        $6.078        $5.167
    End of Period                                $6.929       $7.088       $6.703        $6.201        $6.078
  Number of Units
    Outstanding, End of Period                 1,914,749     2,171,879    2,252,704     2,691,481    2,778,441



  MONEY MARKET DIVISION
    Beginning of Period                          $2.431       $2.335       $2.241        $2.156        $2.063
    End of Period                                $2.523       $2.431       $2.335        $2.241        $2.156
  Number of Units
    Outstanding, End of Period                 7,329,873     6,699,739    6,270,333     7,029,739    7,896,022

</TABLE>

<TABLE>
<CAPTION>

                                                               FOR THE YEARS ENDED DECEMBER 31
                                                 -------------------------------------------------------------
                                                  1994           1993         1992         1991          1990
                                                  ----           ----         ----         ----          ----
<S>                                            <C>           <C>          <C>           <C>          <C>
  SMALL CAP GROWTH STOCK DIVISION
    Beginning of Period*                           --             --           --           --            --
    End of Period                                  --             --           --           --            --
  Number of Units
    Outstanding, End of Period                     --             --           --           --            --

  AGGRESSIVE GROWTH STOCK DIVISION
    Beginning of Period*                           $1.915       $1.628       $1.556       $1.010       $1.000
    End of Period                                  $1.994       $1.915       $1.628       $1.556       $1.010
  Number of Units
    Outstanding, End of Period                   17,290,856   11,319,698   7,939,571     3,208,965     81,406



  INTERNATIONAL EQUITY DIVISION
    Beginning of Period**                          $1.236       $1.000         --           --            --
    End of Period                                  $1.220       $1.236         --           --            --
  Number of Units
    Outstanding, End of Period                   21,538,113    8,548,091       --           --            --



  INDEX 400 STOCK DIVISION
    Beginning of Period*                           --             --           --           --            --
    End of Period                                  --             --           --           --            --
  Number of Units
    Outstanding, End of Period                     --             --           --           --            --



  GROWTH STOCK DIVISION
    Beginning of Period*                           $1.000         --           --           --            --
    End of Period                                  $1.006         --           --           --            --
  Number of Units
    Outstanding, End of Period                    1,311,686       --           --           --            --



  GROWTH AND INCOME STOCK DIVISION
    Beginning of Period*                           $1.000         --           --           --            --
    End of Period                                  $0.994         --           --           --            --
  Number of Units
    Outstanding, End of Period                    3,129,287       --           --           --            --



  INDEX 500 STOCK DIVISION
    Beginning of Period*                           $1.470       $1.356       $1.280       $1.000       $1.000
    End of Period                                  $1.469       $1.470       $1.356       $1.280       $1.000
  Number of Units
    Outstanding, End of Period                   17,624,809   16,051,619  4,774,008      2,593,051     30,451



  BALANCED DIVISION
    Beginning of Period                            $3.480       $3.216       $3.092       $2.526       $2.531
    End of Period                                  $3.436       $3.480       $3.216       $3.092       $2.526
  Number of Units
    Outstanding, End of Period                   59,200,252   63,940,609  62,756,051    59,013,26    58,632,612



  HIGH YIELD BOND DIVISION
    Beginning of Period*                           $1.000         --           --           --            --
    End of Period                                  $1.022         --           --           --            --
  Number of Units
    Outstanding, End of Period                    1,215,989       --           --           --            --



  SELECT BOND DIVISION
    Beginning of Period                            $5.384       $4.941       $4.677       $4.052       $3.787
    End of Period                                  $5.167       $5.384       $4.941       $4.677       $4.052
  Number of Units
    Outstanding, End of Period                    2,923,557    2,937,137  2,667,880      2,087,901    1,970,476



  MONEY MARKET DIVISION
    Beginning of Period                            $2.007       $1.976       $1.936       $1.855       $1.739
    End of Period                                  $2.063       $2.007       $1.976       $1.936       $1.855
  Number of Units
    Outstanding, End of Period                    8,608,326   7,614,186   8,478,941      9,098,558   10,506,714

</TABLE>


#    The initial investments in the Small Cap Growth Stock Division and Index
     400 Stock Division were made on April 30, 1999.
*    The initial investments in the Aggressive Growth Stock Division and Index
     500 Stock Division were made on December 12, 1990.
**   The initial investment in the International Equity Division was made on
     April 30, 1993.
+    The initial investments in the Growth Stock Division, Growth and Income
     Stock Division, and High Yield Bond Division were made on May 3, 1994








                                       9




<PAGE>   18







ACCUMULATION UNIT VALUES
(CONTINUED)

RUSSELL INSURANCE FUNDS
- -----------------------

<TABLE>
<CAPTION>

                                     FOR THE EIGHT MONTHS ENDED                                         FOR THE EIGHT MONTHS ENDED
                                            DECEMBER 31                                                         DECEMBER 31
                                               1999                                                                1999
                                               ----                                                                ----
<S>                                  <C>                              <C>                               <C>
     MULTI-STYLE EQUITY DIVISION                                      REAL ESTATE SECURITIES DIVISION
       Beginning of Period*                   $1.000                    Beginning of Period*                      $1.000
       End of Period                          $1.067                    End of Period                             $ .920
     Number of Units                                                  Number of Units
       Outstanding, End of Period          1,475,825                    Outstanding, End of Period                248,726

     AGGRESSIVE EQUITY DIVISION                                       CORE BOND DIVISION
       Beginning of Period*                   $1.000                    Beginning of Period*                      $1.000
       End of Period                          $1.100                    End of Period                             $ .983
     Number of Units                                                  Number of Units
       Outstanding, End of Period            760,721                    Outstanding, End of Period                580,967

     NON-U.S. DIVISION
       Beginning of Period*                   $1.000
       End of Period                          $1.243
     Number of Units
       Outstanding, End of Period            813,542

</TABLE>

*The initial investment was made on April 30, 1999.













                                       10


<PAGE>   19










ACCUMULATION UNIT VALUES
CONTRACTS ISSUED PRIOR TO DECEMBER 17, 1981

NORTHWESTERN MUTUAL SERIES FUND, INC.
- -------------------------------------

<TABLE>
<CAPTION>
                                                            FOR THE YEARS ENDED DECEMBER 31
                                       --------------------------------------------------------------------

                                         1999         1998           1997           1996           1995
                                         ----         ----           ----           ----           ----
<S>                                   <C>          <C>            <C>            <C>            <C>
SMALL CAP GROWTH STOCK DIVISION
  Beginning of Period#                   $1.000        --             --             --             --
  End of Period                          $1.852        --             --             --             --
Number of Units
  Outstanding, End of Period             95,329        --             --             --             --



AGGRESSIVE GROWTH STOCK DIVISION
  Beginning of Period*                   $3.965       $3.714         $3.286         $2.813         $2.035
  End of Period                          $5.658       $3.965         $3.714         $3.286         $2.813
Number of Units
  Outstanding, End of Period            370,788      479,410        640,838        890,850        861,229


INTERNATIONAL EQUITY DIVISION
  Beginning of Period**                  $1.947       $1.872         $1.680         $1.398         $1.230
  End of Period                          $2.376       $1.947         $1.872         $1.680         $1.398
Number of Units
  Outstanding, End of Period            630,123      647,767      1,297,660      1,332,812      1,166,796


INDEX 400 STOCK DIVISION
  Beginning of Period#                   $1.000        --             --             --             --
  End of Period                          $1.123        --             --             --             --
Number of Units
  Outstanding, End of Period            167,651        --             --             --             --



GROWTH STOCK DIVISION
  Beginning of Period+                   $2.549       $2.027         $1.573         $1.311         $1.009
  End of Period                          $3.100       $2.549         $2.027         $1.573         $1.311
Number of Units
  Outstanding, End of Period            372,659      247,491        327,731        118,168          1,782


GROWTH AND INCOME STOCK DIVISION
  Beginning of Period+                   $2.438       $1.995         $1.546         $1.298         $0.997
  End of Period                          $2.601       $2.438         $1.995         $1.546         $1.298
Number of Units
  Outstanding, End of Period            254,027      310,014        348,188         69,566          9,498


INDEX 500 STOCK DIVISION
  Beginning of Period*                   $4.202       $3.289         $2.488         $2.042         $1.499
  End of Period                          $5.043       $4.202         $3.289         $2.488         $2.042
Number of Units
  Outstanding, End of Period          6,687,760    7,343,357      8,175,537      9,600,286     10,111,615


BALANCED DIVISION
  Beginning of Period                    $7.372       $6.248         $5.180         $4.601         $3.667
  End of Period                          $8.137       $7.372         $6.248         $5.180         $4.601
Number of Units
  Outstanding, End of Period          2,738,126    3,013,626      3,845,538      4,743,812      5,651,599


HIGH YIELD BOND DIVISION
  Beginning of Period+                   $1.582       $1.624         $1.412         $1.188         $1.025
  End of Period                          $1.563       $1.582         $1.624         $1.412         $1.188
Number of Units
  Outstanding, End of Period             77,269      183,181        600,752        428,588          --


SELECT BOND DIVISION
  Beginning of Period                    $7.719       $7.263         $6.685         $6.520         $5.515
  End of Period                          $7.583       $7.719         $7.263         $6.685         $6.520
Number of Units
  Outstanding, End of Period            715,024      899,839      1,012,083      1,215,131      1,172,420


MONEY MARKET DIVISION
  Beginning of Period                    $2.646       $2.529         $2.416         $2.312         $2.201
  End of Period                          $2.761       $2.646         $2.529         $2.416         $2.312
Number of Units
  Outstanding, End of Period            898,198    1,723,332        893,452      1,103,625      1,264,988

</TABLE>

<TABLE>
<CAPTION>

                                                            FOR THE YEARS ENDED DECEMBER 31
                                       --------------------------------------------------------------------
                                         1994          1993           1992           1991           1990
                                         ----          ----           ----           ----           ----
<S>                                   <C>          <C>            <C>            <C>            <C>
SMALL CAP GROWTH STOCK DIVISION
  Beginning of Period#                    --            --             --             --             --
  End of Period                           --            --             --             --             --
Number of Units
  Outstanding, End of Period              --            --             --             --             --



AGGRESSIVE GROWTH STOCK  DIVISION
  Beginning of Period*                  $1.945         $1.645         $1.564         $1.010         $1.000
  End of Period                         $2.035         $1.945         $1.645         $1.564         $1.010
Number of Units
  Outstanding, End of Period           805,409        602,390        459,581        262,149          9,478


INTERNATIONAL EQUITY
DIVISION                                $1.240         $1.000          --             --             --
  Beginning of Period**                 $1.230         $1.240          --             --             --
  End of Period
Number of Units
  Outstanding, End of Period         1,529,309        912,421          --             --             --


INDEX 400 STOCK DIVISION
  Beginning of Period#                    --            --             --             --             --
  End of Period                           --            --             --             --             --
 Number of Units
  Outstanding, End of Period              --            --             --             --             --



GROWTH STOCK DIVISION
  Beginning of Period+                    --            --             --             --             --
  End of Period                           --            --             --             --             --
Number of Units
  Outstanding, End of Period              --            --             --             --             --


GROWTH AND INCOME STOCK
DIVISION                                  --            --             --             --             --
  Beginning of Period+                    --            --             --             --             --
  End of Period
Number of Units                           --            --             --             --             --
  Outstanding, End of Period


INDEX 500 STOCK DIVISION
  Beginning of Period*                  $1.492         $1.370         $1.287         $1.000         $1.000
  End of Period                         $1.499         $1.492         $1.370         $1.287         $1.000
Number of Units
  Outstanding, End of Period        10,735,943     12,320,684        242,871         33,349         13,511


BALANCED DIVISION
  Beginning of Period                   $3.695         $3.398         $3.250         $2.642         $2.635
  End of Period                         $3.667         $3.695         $3.398         $3.250         $2.642
Number of Units
  Outstanding, End of Period         6,525,821      7,060,303      8,324,438      8,795,056      9,637,964


HIGH YIELD BOND DIVISION
  Beginning of Period+                    --            --             --             --             --
  End of Period                           --            --             --             --             --
Number of Units
  Outstanding, End of Period              --            --             --             --             --


SELECT BOND DIVISION
  Beginning of Period                   $5.719         $5.222         $4.918         $4.239         $3.943
  End of Period                         $5.515         $5.719         $5.222         $4.918         $4.239
Number of Units
  Outstanding, End of Period         1,266,751      1,389,667      1,411,347      1,590,698      1,590,884


MONEY MARKET DIVISION
  Beginning of Period                   $2.131         $2.088         $2.035         $1.940         $1.810
  End of Period                         $2.201         $2.131         $2.088         $2.035         $1.940
Number of Units
  Outstanding, End of Period         1,020,911        788,050      1,231,018      1,393,920      2,143,153

</TABLE>


#    The initial investments in the Small Cap Growth Stock Division and Index
     400 Stock Division were made on April 30, 1999.
*    The initial investments in the Index 500 Stock Division and Aggressive
     Growth Stock Division were made on December 12, 1990.
**   The initial investment in the International Equity Division was made on
     April 30, 1993.
+    The initial investments in the Growth Stock Division, Growth and Income
     Stock Division, and High Yield Bond Division were made on May 3, 1994.


                                       11




<PAGE>   20






ACCUMULATION UNIT VALUES
(CONTINUED)

RUSSELL INSURANCE FUNDS
- -----------------------

<TABLE>
<CAPTION>


                                            FOR THE EIGHT MONTHS ENDED                                  FOR THE EIGHT MONTHS ENDED
                                                   DECEMBER 31                                                DECEMBER 31
                                                      1999                                                        1999
                                                      ----                                                        ----
<S>                                         <C>                        <C>                              <C>
     MULTI-STYLE EQUITY DIVISION                                        REAL ESTATE SECURITIES DIVISION
       Beginning of Period*                         $1.000                Beginning of Period*                   $1.000
       End of Period                                $1.071                End of Period                          $ .923
     Number of Units                                                    Number of Units
       Outstanding, End of Period                    7,554                Outstanding, End of Period              4,656

     AGGRESSIVE EQUITY DIVISION                                         CORE BOND DIVISION
       Beginning of Period*                         $1.000                Beginning of Period*                   $1.000
       End of Period                                $1.104                End of Period                          $ .986
     Number of Units                                                    Number of Units
       Outstanding, End of Period                    7,374                 Outstanding, End of Period             2,618

     NON-U.S. DIVISION
       Beginning of Period*                         $1.000
       End of Period                                $1.247
     Number of Units
       Outstanding, End of Period                   12,237
</TABLE>

*The initial investment was made on April 30, 1999.


THE COMPANY


The Northwestern Mutual Life Insurance Company was organized by a special act of
the Wisconsin Legislature in 1857. It is the nation's fifth largest life
insurance company, based on total assets in excess of $85 billion on December
31, 1999, and is licensed to conduct a conventional life insurance business in
the District of Columbia and in all states of the United States. Northwestern
Mutual sells life and disability income insurance policies and annuity contracts
through its own field force of approximately 6,000 full time producing agents.
The Home Office of Northwestern Mutual is located at 720 East Wisconsin Avenue,
Milwaukee, Wisconsin 53202.


"We" in this prospectus means Northwestern Mutual.


NML VARIABLE ANNUITY ACCOUNT A

We established the Account on February 14, 1968 by action of our Board of
Trustees in accordance with the provisions of the Wisconsin insurance law.

The Account has sixteen Divisions. The money you invest to provide variable
benefits under your Contract is placed in one or more of the Divisions as you
direct.

Under Wisconsin law, the investment operations of the Account are kept separate
from our other operations. The values for your Contract will not be affected by
income, gains or losses for the rest of our business. The income, gains or
losses, realized or unrealized, for the assets we place in the Account for your
Contract will determine the value of your Contract benefits and will not affect
the rest of our business. The assets in the Account are reserved for you and
other Contract owners, although the assets belong to us and we do not hold the
assets as a trustee. We and our creditors cannot reach those assets to satisfy
other obligations until our obligations under your Contract have been satisfied.
But all of our assets (except those we hold in some other separate accounts) are
available to satisfy our obligations under your Contract.

The Account is not registered as an investment company under the Investment
Company Act of 1940.

THE FUNDS

Northwestern Mutual Series Fund, Inc. is composed of eleven separate portfolios
which operate as separate mutual funds. The portfolios are the Small Cap Growth
Stock Portfolio, Aggressive Growth Stock Portfolio, International Equity
Portfolio, Index 400 Stock Portfolio, Growth Stock Portfolio, Growth and Income
Stock Portfolio, Index 500 Stock Portfolio, Balanced Portfolio, High Yield Bond
Portfolio, Select Bond Portfolio and Money Market Portfolio. The Account buys
shares of each Portfolio at net asset value, that is, without any sales charge.




                                     12
<PAGE>   21

Northwestern Mutual Investment Services, LLC ("NMIS"), our wholly-owned
subsidiary, is the investment adviser to the Fund. We provide the people and
facilities that NMIS uses in performing its investment advisory functions, and
we are a party to the investment advisory agreement. NMIS has retained J.P.
Morgan Investment Management, Inc. and Templeton Investment Counsel, Inc. under
investment sub-advisory agreements to provide investment advice to the Growth
and Income Stock Portfolio and the International Equity Portfolio.

The Russell Insurance Funds include five separate portfolios which operate as
separate mutual funds. These are the Multi-Style Equity Fund, Aggressive Equity
Fund, Non-U.S. Fund, Real Estate Securities Fund and Core Bond Fund. The Account
buys shares of each of the Russell Insurance Funds at net asset value, that is,
without any sales charge.

The assets of each of the Russell Insurance Funds are invested by one or more
investment management organizations researched and recommended by Frank Russell
Company ("Russell"), and an affiliate of Russell, Frank Russell Investment
Management Company ("FRIMCo"). FRIMCo also advises, operates and administers the
Russell Insurance Funds. Russell is our majority-owned subsidiary.

FOR MORE INFORMATION REGARDING THE MUTUAL FUNDS, INCLUDING INFORMATION ABOUT
THEIR INVESTMENT OBJECTIVES AND EXPENSES, SEE THE PROSPECTUSES FOR NORTHWESTERN
MUTUAL SERIES FUND, INC. AND RUSSELL INSURANCE FUNDS ATTACHED TO THIS
PROSPECTUS. YOU SHOULD READ THE MUTUAL FUND PROSPECTUSES CAREFULLY BEFORE YOU
INVEST IN THE CONTRACTS.

- --------------------------------------------------------------------------------
THE CONTRACTS

PURCHASE PAYMENTS UNDER THE CONTRACTS

AMOUNT AND FREQUENCY A purchase payment is the money you give us to pay for your
Contract. You may make purchase payments monthly, quarterly, semiannually,
annually or on any other frequency acceptable to us.

For Back Load Contracts the minimum amount for each purchase payment is $25. We
will accept larger purchase payments than due, or payments at other times, but
total purchase payments under any Contract may not exceed $5,000,000 without our
consent. For Front Load Contracts the minimum initial purchase payment is
$10,000. The minimum amount for each subsequent purchase payment is $25 for all
Contracts.

Purchase payments may not exceed the applicable federal income tax limits. See
"Federal Income Taxes", p. 18.

APPLICATION OF PURCHASE PAYMENTS We credit net purchase payments, after
deduction of any sales load, to the Account and allocate them to one or more
Divisions as you direct. We then invest those assets in shares of the Portfolio
or Fund which corresponds to that Division.


We apply purchase payments to provide "Accumulation Units" in one or more
Divisions. Accumulation Units represent your interest in the Account. There are
Class A Accumulation Units and Class B Accumulation Units for the Back Load
Contracts. We credit Class B Accumulation Units to your Back Load Contract each
time you make a purchase payment. We convert Class B Accumulation Units to Class
A Accumulation Units on a basis that reflects the cumulative amount of purchase
payments and the length of time that the funds have been held under a Back Load
Contract. See "Mortality Rate and Expense Risk Charges", p. 19. The number of
Accumulation Units you receive for each net purchase payment is determined by
dividing the amount of the purchase payment to be allocated to a Division by the
value of an Accumulation Unit in that Division, based upon the next valuation of
the assets of the Division we make after we receive your purchase payment at our
Home Office. Receipt of purchase payments at a lockbox facility we have
designated will be considered the same as receipt at the Home Office. We value
assets as of the close of trading on the New York Stock Exchange for each day
the Exchange is open, and at any other time required by the Investment Company
Act of 1940.


The number of your Accumulation Units will be increased by additional purchase
payments or transfers into the Account and decreased by withdrawals or transfers
out of the Account. The investment experience of the Account does not change the
number (as distinguished from the value) of your Accumulation Units.


The value of an Accumulation Unit in each Division varies with the investment
experience of the Division (which in turn is determined by the investment
experience of the corresponding Portfolio or Fund). We determine the value by
multiplying the value on the immediately preceding valuation date by the net
investment factor for the Division. The net investment factor takes into account
the investment experience of the Portfolio or Fund, the deduction for mortality
and expense risks we have assumed and a deduction for any applicable taxes or
for any expenses resulting from a substitution of securities. (See "Net
Investment Factor", p. 14.) Since you bear the investment risk, there is no
guarantee as to the aggregate value of your Accumulation Units. That value may
be less than, equal to, or more than the cumulative net purchase payments you
have made.


                                       13
<PAGE>   22
You may direct all or part of a purchase payment to the Guaranteed Interest
Fund. Amounts you direct to the Guaranteed Interest Fund will be invested on a
fixed basis. See "The Guaranteed Interest Fund", p. 17.

NET INVESTMENT FACTOR

For each Division the net investment factor for any period ending on a valuation
date is 1.000000 plus the net investment rate for the Division for that period.
Under the Contract the net investment rate is related to the assets of the
Division. However, since all amounts are simultaneously invested in shares of
the corresponding Portfolio or Fund when allocated to the Division, calculation
of the net investment rate for each of the Divisions may also be based upon the
change in value of a single share of the corresponding Portfolio or Fund.

Thus, for example, in the case of the Balanced Division the net investment rate
is equal to (a) the change in the net asset value of a Balanced Portfolio share
for the period from the immediately preceding valuation date up to and including
the current valuation date, plus the per share amount of any dividends and other
distributions made by the Balanced Portfolio during the valuation period, less a
deduction for any applicable taxes or for any expenses resulting from a
substitution of securities, (b) divided by the net asset value of a Balanced
Portfolio share on the valuation date immediately preceding the current
valuation date, (c) less an adjustment to provide for the deduction for
mortality rate and expense risks that we have assumed. (See "Deductions", p.
19.)

The Portfolios and Funds will distribute investment income and realized capital
gains to the Account Divisions. We will reinvest those distributions in
additional shares of the same Portfolio or Fund. Unrealized capital gains and
realized and unrealized capital losses will be reflected by changes in the value
of the shares held by the Account.

BENEFITS PROVIDED UNDER THE CONTRACTS

The benefits provided under the Contracts consist of a withdrawal amount, a
death benefit and a maturity benefit. Subject to the restrictions noted below,
we will pay all of these benefits in a lump sum or under the payment plans
described below.


WITHDRAWAL AMOUNT On or prior to the maturity date you are entitled to withdraw
the Accumulation Units credited to your Contract and receive the value thereof
less the applicable withdrawal charge. (See "Withdrawal Charge", p. 20.) The
value, which may be either greater or less than the amount you paid, is based on
the Accumulation Unit value next determined after we receive your written
request for withdrawal on a form we provide. The forms are available from our
Home Office and our agents. You may withdraw a portion of the Accumulation Units
on the same basis, except that we will not grant a partial withdrawal which
would result in a Contract value of less $2,000 remaining; we will treat a
request for such a partial withdrawal as a request to surrender the entire
Contract. Amounts distributed to you upon withdrawal of all or a portion of
Accumulation Units may be subject to federal income tax. (See "Federal Income
Taxes", p. 18.) A 10% penalty tax may be imposed on the taxable portion of
premature payments of benefits (prior to age 59-1/2 or disability) unless
payments are made after the employee separates from service and payments are
either paid in substantially equal installments over the life or life expectancy
of the employee or are paid on account of early retirement after age 55.


If annuity payments are being made under Payment Plan 1 the payee may surrender
the Contract and receive the value of the Annuity Units credited to his
Contract, less the applicable withdrawal charge. (See "Withdrawal Charge", p.
20) Upon death during the certain period of the payee under Plan 2 or both
payees under Plan 3, the beneficiary may surrender the Contract and receive the
withdrawal value of the unpaid payments for the certain period. The withdrawal
value is based on the Annuity Unit value on the withdrawal date, with the unpaid
payments discounted at the Assumed Investment Rate. (See "Description of Payment
Plans", p.15.)

DEATH BENEFIT


1. Amount of the Death Benefit. If the Annuitant dies before the maturity date,
the death benefit will not be less than the Contract value next determined after
we receive proof of death at our Home Office. If the Primary Annuitant dies
before his or her 75th birthday, the death benefit, where permitted by state
law, will not be less than the amount of purchase payments we received, less
withdrawals. There is no death benefit after annuity payments begin. See
"Maturity Benefit", p. 15 and "Variable Payment Plans", p. 15.


An enhanced death benefit is available at extra cost. Prior to the first
Contract anniversary the enhanced death benefit is equal to the total purchase
payments received less any amounts withdrawn. On any Contract anniversary prior
to the Primary Annuitant's 80th birthday, the enhanced death benefit is the
Contract value on that date, but not less than what the enhanced death benefit
was on the last preceding valuation date. On any other valuation date before the
Primary Annuitant's 80th birthday, the enhanced death benefit will be the amount
determined on the most recent Contract anniversary, plus purchase payments we
receive thereafter, less withdrawals. On any valuation date on or after the
Primary Annuitant's 80th birthday the enhanced death benefit will be the
enhanced death benefit on the Contract anniversary immediately prior to the
Primary Annuitant's 80th birthday increased by purchase payments we received and
decreased by any amounts withdrawn after that Contract anniversary. We deduct
the extra cost for the enhanced death benefit from the Contract value on each
Contract anniversary while the enhanced death benefit is in effect. See
"Enhanced Death Benefit Charge", p. 20. The

                                       14
<PAGE>   23

enhanced death benefit is available for issue ages up to 65 and must be elected
when the Contract is issued. The enhanced death benefit will remain in effect
until the maturity date or the death of the Primary Annuitant or you ask us to
remove it from your Contract. You cannot add it to your Contract again after it
has been removed.

2. Distribution of the Death Benefit.


When the employee dies, the contingent Annuitant automatically becomes the new
Annuitant and the Contract continues in force, beginning with a value equal to
the death benefit. The Owner, if living, or otherwise the beneficiary may elect
to receive the death benefit in a lump sum or under a payment plan. See
"Variable Payment Plans", below. If no contingent annuitant has been named, the
death benefit becomes payable to the Owner.


MATURITY BENEFIT Purchase payments under the Contract are payable until the
maturity date specified in the Contract. You may select any date up to age 90 as
the maturity date, subject to applicable tax and state law requirements,
including the minimum distribution requirements (See "Minimum Distribution
Requirements, p. 18). On the maturity date, if you have not elected any other
permissible payment plan, we will change the maturity date to the Contract
anniversary nearest the Annuitant's 90th birthday. On that date, if you have not
elected any other permissible payment plan, we will pay the value of the
Contract in monthly payments for life under a variable payment plan with
payments certain for ten years.

VARIABLE PAYMENT PLANS


We will pay part or all of the benefits under a Contract under a variable
payment plan you select. Under a variable plan, you bear the entire investment
risk, since we make no guarantees of investment return. Accordingly, there is no
guarantee of the amount of the variable payments, and you must expect the amount
of such payments to change from month to month. For a discussion of tax
considerations and limitations regarding the election of payment plans, see
"Federal Income Taxes", p. 18.


DESCRIPTION OF PAYMENT PLANS The following payment plans are available:

1. Payments for a Certain Period. An annuity payable monthly for a specified
period of five to 30 years.

2. Life Annuity with or without Certain Period. An annuity payable monthly until
the payee's death, or until the expiration of a selected certain period,
whichever is later. After the payee's death during the certain period, if any,
we will make payments as they are due to the designated contingent beneficiary.
You may select a certain period of either 10 or 20 years, or you may choose a
plan with no certain period.

3. Joint and Survivor Life Annuity with Certain Period. An annuity payable
monthly for a certain period of 10 years and thereafter to two persons for their
joint lives. On the death of either payee, payments continue for the remainder
of the 10 years certain or the remaining lifetime of the survivor, whichever is
longer. We may limit the election of a payment plan to one that results in an
initial payment of at least $50. A payment plan will continue even if payments
fall to less than $50 after the payment plan begins.


From time to time we may establish payment plan rates with greater actuarial
value than those stated in the Contract and make them available at the time of
settlement. We may also make available other payment plans, with provisions and
rates we publish for those plans.


AMOUNT OF ANNUITY PAYMENTS We will determine the amount of the first annuity
payment on the basis of the particular payment plan you select, the annuity
payment rate and, for plans involving life contingencies, the Annuitant's
adjusted age. We will calculate the amount of the first annuity payment on a
basis that takes into account the length of time over which we expect annuity
payments to continue. The first payment will be lower for an Annuitant who is
younger when payments begin, and higher for an Annuitant who is older, if the
payment plan involves life contingencies. The first payment will be lower if the
payment plan includes a longer certain period. Variable annuity payments after
the first will vary from month to month to reflect the fluctuating value of the
Annuity Units credited to your Contract. Annuity Units represent the interest of
the Contract in each Division of the Account after annuity payments begin. Class
A Accumulation Units become Class A Annuity Units and Class B Accumulated Units
become Class B Annuity Units on the maturity date.

ASSUMED INVESTMENT RATE The variable annuity rate tables for the Contracts are
based upon an Assumed Investment Rate of 3 1/2%. Variable annuity rate tables
based upon an Assumed Investment Rate of 5% are also available where permitted
by state law.

The Assumed Investment Rate affects both the amount of the first variable
payment and the amount by which subsequent payments increase or decrease. The
Assumed Investment Rate does not affect the actuarial value of the future
payments as of the date when payments begin, though it does affect the actual
amount which may be received by an individual Annuitant.


Over a period of time, if each Division achieved a net investment result exactly
equal to the Assumed Investment Rate applicable to a particular payment plan,
the amount of annuity payments would be level. However, if the Division achieved
a net investment result greater than the Assumed Investment Rate, the amount of
annuity payments would increase. Similarly, if the Division achieved a net
investment result smaller than the Assumed Investment Rate, the amount of
annuity payments would decrease.



                                       15

<PAGE>   24
A higher Assumed Investment Rate will result in a larger initial payment but
more slowly rising and more rapidly falling subsequent payments than a lower
Assumed Investment Rate.

ADDITIONAL INFORMATION

TRANSFERS BETWEEN DIVISIONS AND PAYMENT PLANS You may change the allocation of
purchase payments among the Divisions and transfer values from one Division to
another both before and after annuity payments begin. In order to take full
advantage of these features you should carefully consider, on a continuing
basis, which Division or apportionment is best suited to your long-term
investment needs.

You may at any time change the allocation of purchase payments among the
Divisions by written notice to us. Purchase payments we receive at our Home
Office on and after the date on which we receive the notice will be applied to
provide Accumulation Units in one or more Divisions on the basis of the new
allocation.

Before the effective date of a payment plan you may, upon written request,
transfer Accumulation Units from one Division to another. After the effective
date of a payment plan the payee may transfer Annuity Units from one Division to
another. We will adjust the number of Accumulation or Annuity Units to be
credited to reflect the respective value of the Accumulation and Annuity Units
in each of the Divisions. For Accumulation Units the minimum amount which may be
transferred is the lesser of $100 or the entire value of the Accumulation Units
in the Division from which the transfer is being made. For each transfer
beginning with the thirteenth in any Contract year we may deduct a transfer fee
of $25 from the amount transferred. We currently make no charge for transfers.

If you contemplate the transfer of funds from one Division to another, you
should consider the risk inherent in a switch from one investment medium to
another. In general, frequent transfers based on short-term expectations for the
stock and bond markets, especially transfers of large sums, will tend to
accentuate the danger that a transfer will be made at an inopportune time.

You may transfer amounts which you have invested on a fixed basis to any
Division of the Account, and the value of Accumulation Units in any Division of
the Account to the Guaranteed Interest Fund for investment on a fixed basis,
subject to the restrictions described in the Contract. See "The Guaranteed
Interest Fund", p. 17.

After the effective date of a payment plan which does not involve a life
contingency (i.e., Plan 1) a payee may transfer to either form of life annuity
at no charge. We will apply the value of the remaining payments to the new plan
selected. We will determine the amount of the first annuity payment under the
new plan on the basis of the particular plan selected, the annuity payment rate
and the Annuitant's adjusted age and sex. Subsequent payments will vary to
reflect changes in the value of the Annuity Units credited. We permit other
transfers between payment plans subject to such limitations we may reasonably
determine. Generally, however, we do not permit transfer from a payment plan
involving a life contingency to a payment plan which does not involve the same
life contingency.

You may make transfers from the Money Market Division at any time while a
payment plan is in force. The Contracts provide that transfers between the other
Divisions and transfers between payment plans may be made after the payment plan
has been in force for at least 90 days and thereafter whenever at least 90 days
have elapsed since the date of the last transfer. At present we permit transfers
at any time. We will make the transfer as of the close of business on the
valuation date coincident with or next following the date on which we receive
the request for transfer at our Home Office, or at a later date you request.

GENDER-BASED ANNUITY PAYMENT RATES Federal law, and the laws of certain states,
may require that annuity considerations and annuity payment rates be determined
without regard to the sex of the Annuitant. Because we offer the Contracts for
use with HR-10 Plans where these rules may have general application, the annuity
payment rates in the Contracts do not distinguish between male and female
Annuitants. However, Contracts with sex-distinct rates are available on request.
Prospective purchasers of the Contracts should review any questions in this area
with qualified counsel.

OWNERS OF THE CONTRACTS The Owner of the Contract has the sole right to exercise
all rights and privileges under the Contract, except as the Contract otherwise
provides. The Owner is ordinarily the retirement plan, but may be the employer
or the Annuitant or other person. The Annuitant is the person upon whose life
the Contract is issued and Contract benefits depend. The Primary Annuitant is
the person upon whose life the Contract is initially issued. The Contingent
Annuitant is the person who becomes the Annuitant upon the death of the
Annuitant. In this prospectus, "you" means the Owner or a prospective purchaser
of the Contract.

DEFERMENT OF BENEFIT PAYMENTS We reserve the right to defer determination of the
withdrawal value of the Contracts, or the payment of benefits under a variable
payment plan, until after the end of any period during which the right to redeem
shares of either of the mutual funds is suspended, or payment of the redemption
value is postponed, and for any period during which the New York Stock Exchange
is closed or trading thereon is restricted or an emergency exists, so that
valuation of the assets of the Fund or disposal of securities they hold is not
reasonably practical; or as such deferment is otherwise permitted by applicable
law.

DIVIDENDS The Contracts share in our divisible surplus, to the extent we
determine annually, except while payments are being made under a variable
payment

                                       16
<PAGE>   25

plan. Distributions of divisible surplus are commonly referred to as
"dividends". Any contributions to our divisible surplus would result from more
favorable expense experience than we have assumed in determining the deductions.
We do not expect the Contracts to make a significant contribution to our
divisible surplus and we do not expect to pay dividends on the Contracts.

For the Back Load Contracts we reduce expense charges by converting Class B
Accumulation Units to Class A Accumulation Units on larger, older Contracts. See
"Mortality Rate and Expense Risk Charges", p. 19. The Contracts issued prior to
the date of this prospectus do not include this conversion feature, and we
currently pay dividends on some of those Contracts. See "Dividends for Contracts
Issued Prior to March 31, 2000", p. 21.

SUBSTITUTION AND CHANGE Pursuant to authority of our Board of Trustees, (a) we
may invest the assets of a Division in securities of another mutual fund or
another issuer, instead of the Portfolio or Fund in which you have invested, as
a substitute for the shares you already have or as the securities to be
purchased in the future, or (b) we may modify the provisions of the Contracts to
assure qualification for the benefits provided by the provisions of the Internal
Revenue Code relating to retirement annuity or variable annuity contracts, or to
comply with any other applicable federal or state laws. In the event of any such
substitution or change, we may make appropriate endorsement on Contracts having
an interest in the Account and take such other action as may be necessary to
effect the substitution or change.

FIXED ANNUITY PAYMENT PLANS We will also pay Contract benefits under fixed
annuity payment plans which are not described in this Prospectus. If you select
a fixed annuity, we will cancel the Accumulation Units credited to your Deferred
Contract, we will transfer the withdrawal value of the Contract to our general
account, and you will no longer have any interest in the Account. We may make a
withdrawal charge in determining the withdrawal value. (See "Withdrawal Amount",
p. 14, and "Withdrawal Charge", p. 20)


FINANCIAL STATEMENTS Financial statements of the Account and financial
statements of Northwestern Mutual appear in the Statement of Additional
Information.


- --------------------------------------------------------------------------------
THE GUARANTEED INTEREST FUND

You may direct all or part of your purchase payments to the Guaranteed Interest
Fund for investment on a fixed basis. You may transfer amounts previously
invested in the Account Divisions to the Guaranteed Interest Fund, prior to the
maturity date, and you may transfer amounts in the Guaranteed Interest Fund to
the Account Divisions. In each case these transfers are subject, to the
restrictions described in the Contract.

Amounts you invest in the Guaranteed Interest Fund become part of our general
assets. In reliance on certain exemptive and exclusionary provisions, we have
not registered interests in the Guaranteed Interest Fund under the Securities
Act of 1933 and we have not registered the Guaranteed Interest Fund as an
investment company under the Investment Company Act of 1940. Accordingly,
neither the Guaranteed Interest Fund nor any interests therein are generally
subject to these Acts. We have been advised that the staff of the Securities and
Exchange Commission has not reviewed the disclosure in this prospectus relating
to the Guaranteed Interest Fund. This disclosure, however, may be subject to
certain generally applicable provisions of the federal securities laws relating
to the accuracy and completeness of statements made in prospectuses.

Amounts you invest in the Guaranteed Interest Fund earn interest at rates we
declare from time to time. We will guarantee the interest rate for each amount
for at least one year. The interest rate will be at an annual effective rate of
at least 3%. At the expiration of the period for which we guarantee the interest
rate, a new interest rate may apply. We credit interest and compound it daily.
We determine the effective date for a transaction involving the Guaranteed
Interest Fund in the same manner as the effective date for a transaction
involving a Division of the Account.

Investments in the Guaranteed Interest Fund are subject to a maximum limit of
$1,000,000 ($250,000 in New York) without our prior consent. To the extent that
a purchase payment or transfer from a Division of the Account causes the
Contract's interest in the Guaranteed Interest Fund to exceed this maximum
limit, we will place the amount of the excess in the Money Market Division and
it will remain there until the you instruct us otherwise.

Transfers from the Guaranteed Interest Fund to the Account Divisions are subject
to limits. After a transfer from the Guaranteed Interest Fund we will allow no
further transfers from the Guaranteed Interest Fund for a period of 365 days; in
addition, we will allow no further transfers back into the Guaranteed Interest
Fund for a period of 90 days. The maximum amount that you may transfer from the
Guaranteed Interest Fund in one transfer is the greater of (1) 25% of the amount
that you had invested in the Guaranteed Interest Fund as of the last Contract
anniversary preceding the transfer and (2) the amount of your most recent
transfer from the Guaranteed Interest Fund. But in no event will this maximum
transfer amount be less than $1,000 or more than $50,000. (The $50,000 limit
does not apply in New York.)

The deduction for mortality rate and expense risks, as described below, is not
assessed against amounts in the Guaranteed Interest Fund, and amounts in the
Guaranteed Interest Fund do not bear any expenses of

                                       17
<PAGE>   26

either of the mutual funds. Other charges under the Contracts apply for amounts
in the Guaranteed Interest Fund as they are described in this prospectus for
amounts you invest on a variable basis. (See "Deductions", p. 19). For purposes
of allocating and deducting the annual Contract fee, we consider any investment
in the Guaranteed Interest Fund as though it were an investment of the same
amount in one of the Account Divisions.

- --------------------------------------------------------------------------------
FEDERAL INCOME TAXES

We offer the Contracts only for use under tax-qualified plans meeting the
requirements of Sections 401 and 403(a) of the Code. However, in the event
Contracts should be issued pursuant to HR-10 Plans, trusts or custodial accounts
which at the time of issuance are not qualified under the Code, some or all of
the tax benefits described herein may be lost.

CONTRIBUTION LIMITS

Any employer, including a self-employed person, can establish a plan under
Section 401(a) or 403(a) for participating employees. As a general rule, annual
contributions to a defined contribution plan made by the employer and the
employee cannot exceed the lesser of $30,000 or 25% of compensation or earned
income (up to $170,000, indexed).

Qualified plans are subject to minimum coverage, nondiscrimination and spousal
consent requirements. In addition, "top heavy" rules apply if more than 60% of
the contributions or benefits are allocated to certain highly compensated
employees. Violations of the contribution limits or other requirements may
disqualify the plan and/or subject the employer to taxes and penalties.

TAXATION OF CONTRACT BENEFITS


No tax is payable as a result of any increase in the value of a Contract until
benefits from the Contract are received. Benefits received as annuity payments
will be taxable as ordinary income when received in accordance with Section 72
of the Code. As a general rule, where an employee makes nondeductible
contributions to the Plan, the payee may exclude from income that portion of
each benefit payment which represents a return of the employee's "investment in
the contract" as defined in Section 72 until the entire "investment in the
contract" is recovered. In addition, a 10% penalty tax may be imposed on
benefits paid in excess of the benefits provided under the Plan formula if the
payee is or was a "5% owner" of the employer while a participant in the Plan.


Benefits paid in a form other than an annuity will be taxed as ordinary income
when received except for that portion of the payment, if any, which represents a
return of the employee's "investment in the contract." Benefits received as a
"lump sum distribution" may be eligible for a separate tax averaging calculation
and, with certain limited exceptions, all benefits are subject to the tax-free
rollover provisions of the Code. A 10% penalty tax may be imposed on the taxable
portion of premature payments of benefits (prior to age 59-1/2 or disability)
unless payments are made after the employee separates from service and payments
are either paid in substantially equal installments over the life or life
expectancy of the employee or are paid on account of early retirement after age
55 or unless payments are made for medical expenses in excess of 7.5% of the
employee's Adjusted Gross Income.

A loan from the Plan to an employee, other than an owner-employee, may be
taxable as ordinary income depending on the amount and terms of the loan. A loan
to an owner-employee is a prohibited transaction under the Code and could
disqualify the Plan.

Benefit payments will be subject to mandatory 20% withholding unless (1) they
are rolled over directly to another tax-qualified plan or an individual
retirement arrangement, (2) they are paid in substantially equal installments
over the life or life expectancy of the employee (or of the employee and the
employee's beneficiary) or over a period of 10 years or more, or (3) they are
"required minimum distributions."


MINIMUM DISTRIBUTION REQUIREMENTS As a general rule, the Plan is required to
make certain required distributions to the employee during the employee's life
and to the employee's beneficiary following the employee's death. A 50% penalty
tax may be imposed on payments to the extent they are less than certain required
minimum amounts.


The Plan must make the first required distribution by the "required beginning
date" and subsequent required distributions by December 31 of that year and each
year thereafter. Payments must be made over the life or life expectancy of the
employee or the lives or life expectancies of the employee and the employee's
beneficiary. The required beginning date is April 1 of the calendar year
following the later of the calendar year in which the employee attains age 70
1/2 or, if the employee is not a "5% owner" of the employer, the calendar year
in which the employee retires.

Upon the death of the employee, the Plan must make distributions under one of
the following two rules.

If the employee dies on or after the required beginning date, any remaining
interest of the employee must be distributed at least as rapidly as it was under
the method of distribution in effect on the date of death. The method of
distribution is determined by the age of the employee and the beneficiary and
whether their life expectancies are being recalculated each year.

If the employee dies before the required beginning date, the employee's entire
interest must be distributed by

                                       18

<PAGE>   27

December 31 of the calendar year containing the fifth anniversary of the
employee's death. If the employee's interest is payable to a beneficiary
designated by the employee, the employee's interest may be paid over the life or
life expectancy of that beneficiary, provided distribution begins by December 31
of the calendar year following the year of the employee's death. If the sole
designated beneficiary is the employee's spouse, the spouse may roll over the
Contract into an IRA owned by the spouse.

The rules governing Plan provisions, payments and deductions and taxation of
distributions from such Plans and Trusts, as set forth in the Code and the
regulations relating thereto, are complex and cannot be readily summarized.
Furthermore, special rules are applicable in many situations, and prospective
purchasers desiring to adopt an HR-10 pension or profit-sharing plan or trust
should consult qualified tax counsel.


TAXATION OF NORTHWESTERN MUTUAL

We may charge the appropriate Contracts with their shares of any tax liability
which may result from the maintenance or operation of the Divisions of the
Account. We are currently making no charge. (See "Net Investment Factor", p. 14
and "Deductions", below.)


- --------------------------------------------------------------------------------
DEDUCTIONS

We will make the following deductions:

SALES LOAD For the Front Load Contract we deduct a sales load from all purchase
payments we receive. The sales load compensates us for the costs we incur in
selling the Contracts. We base the deduction on cumulative purchase payments we
have received and the rates in the table below:

<TABLE>
<CAPTION>
Cumulative Purchase Payments
Paid Under the Contract                          Rate
- -----------------------                          ----
<S>                                              <C>
First $100,000                                   4.5%
Next $400,000                                    2.0%
Next $500,000                                    1.0%
Balance over $1,000,000                          0.5%
</TABLE>

MORTALITY RATE AND EXPENSE RISK CHARGES


Amount of Mortality Rate and Expense Risk Charges. The net investment factor
(see "Net Investment Factor", p. 14) we use in determining the value of
Accumulation and Annuity Units reflects a deduction on each valuation date for
mortality rate and expense risks we have assumed. For the Front Load Contract,
the deduction from Accumulation Units and Annuity Units is at a current annual
rate of 0.5% of the assets of the Account. For the Back Load Contract the
deduction for Class B Accumulation Units and Class B Annuity Units is at a
current annual rate of 1.25% of the assets of the Account. For the Back Load
Contracts the deduction for Class A Accumulation Units and Class A Annuity Units
is at a current annual rate of 0.5% of the assets of the Account. Our Board of
Trustees may increase or decrease the deduction, but in no event may the
deduction exceed an annual rate of 0.75% for the Front Load Contract, 1.50% for
the Back Load Contract Class B Accumulation and Annuity Units, and 0.75% for the
Back Load Contract Class A Accumulation and Annuity Units. We will not increase
the deduction for mortality and expense risks for at least five years from the
date of this prospectus.


Reduction in Mortality Rate and Expense Risk Charges. For the Back Load
Contracts we convert Class B Accumulation Units to Class A Accumulation Units on
a Contract anniversary if the Contract value is at least $25,000 and the
purchase payment which paid for the Class B Accumulation Units has reached
Category Zero, that is, its withdrawal charge rate is 0%. See "Withdrawal
Charge" p. 20.


As a result of the conversion, the mortality rate and expense risks charge is
reduced from 1.25% to 0.50% on these units based on current rates. The
conversion amount includes the purchase payment in Category Zero and a
proportionate share of investment earnings. We allocate the conversion amount
proportionately to each Division, and we adjust the number of Accumulation Units
in each Division to reflect the relative values for Class A and Class B
Accumulation Units on the date of the conversion. The same conversion process
and a similar result applies to amounts in the Guaranteed Interest Fund. We do
not convert Class A Accumulation Units back to Class B Accumulation Units even
if the value of your Contract falls below $25,000. We do not convert Annuity
Units from Class B to Class A.


Risks and Expenses. The risks we assume are (a) the risk that annuity payments
will continue for longer periods than anticipated because the Annuitants as a
group live longer than expected, and (b) the risk that the charges we make may
be insufficient to cover the actual costs we incur in connection with the
Contracts. We assume these risks for the duration of the Contract. The deduction
for these risks is the only expense item paid by the Account to date. The mutual
funds pay expenses which are described in the attached prospectuses for the
mutual funds.


The net investment factor also reflects the deduction of any reasonable expenses
which may result if there were a substitution of other securities for shares of
the mutual funds as described under "Substitution and Change", p. 17, and any
applicable taxes, i.e., any tax liability we have paid or reserved for resulting
from the maintenance or operation of a Division of the Account, other than
applicable premium taxes which we may deduct directly from considerations. We do
not presently anticipate that we will make any deduction for federal income
taxes (see "Taxation of Northwestern Mutual", p. 19), nor do we anticipate that
maintenance


                                       19
<PAGE>   28

or operation of the Account will give rise to any deduction for state or local
taxes. However, we reserve the right to charge the appropriate Contracts with
their shares of any tax liability which may result under present or future tax
laws from the maintenance or operation of the Account or to deduct any such tax
liability in the computation of the net investment factor for such Contracts.



CONTRACT FEE On each Contract anniversary prior to the maturity date we make a
deduction of $30 for administrative expenses relating to a Deferred Contract
during the prior year. We make the charge by reducing the number of Accumulation
Units credited to the Contract. For purposes of allocating and deducting the
annual Contract fee, we consider any investment in the Guaranteed Interest Fund
as though it were an investment of the same amount in one of the Account
Divisions. We cannot increase this charge. The charge is intended only to
reimburse us for our actual administrative expenses. We currently are waiving
the charge, if the Contract value on the Contract anniversary is $25,000 or
more.

WITHDRAWAL CHARGE

Withdrawal Charge Rates. For Back Load Contracts, a withdrawal charge free
amount is available on a Contract if the Contract value is at least $10,000 on
the Contract anniversary preceding the withdrawal. For each Contract year after
the first one, the withdrawal charge free amount is 10% of the value of the
Class B Accumulation Units on the last Contract anniversary. Otherwise, we will
deduct a withdrawal charge for sales expenses if you withdraw Class B
Accumulation Units for cash. We will base the withdrawal charge on the
Categories and the Rates in the table below. We base the amount in each Category
on cumulative purchase payments you have made and on the number of Contract
anniversaries that have occurred since you made each purchase payment.

<TABLE>
<CAPTION>
Category                                         Rate
- --------                                         ----
<S>                                              <C>
Eight.............................................6%
Seven.............................................6
Six...............................................6
Five..............................................5
Four..............................................4
Three.............................................3
Two...............................................2
One...............................................1
Zero..............................................0
</TABLE>

The first $100,000 of total purchase payments paid over the life of the Contract
start in Category Eight, the next $400,000 start in Category Four, and all
additional purchase payments paid start in Category Two. As of each Contract
anniversary, we move any amount in a Category to the next lower Category until
the Contract anniversary on which that amount reaches Category Zero. The total
withdrawal charge will be the sum of all the results calculated by multiplying
the amount in each Category by the Rate for that Category. The amounts we use
will be taken first from the withdrawal charge free amount; next from the Class
A Accumulation Units; next from the Class B Accumulation Units in the order that
produces the lowest withdrawal charge; and last from any remaining value in the
contract. However, any amounts we use to determine the charge for a partial
withdrawal will not be used to determine subsequent withdrawal charges.

Waiver of Withdrawal Charges. When we receive proof of death of the Primary
Annuitant, we will waive withdrawal charges applicable at the date of death by
moving purchase payments received prior to the date of death to Category Zero.

We will waive the withdrawal charge if the Primary Annuitant has a terminal
illness, or is confined to a nursing home or hospital after the first contract
year, in accordance with the terms of the Contract. You may not make purchase
payments after we are given proof of a terminal illness or confinement.

We will make no withdrawal charge when you select a variable payment plan.
However, we will make the withdrawal charge if you make a withdrawal, or partial
withdrawal, within five years after the beginning of a variable payment plan
which is not contingent on the payee's life (Plan 1).

For fixed payment plans the Contract provides for deduction of the withdrawal
charge when the payment plan is selected. By current administrative practice, we
will waive the withdrawal charge upon selection of a fixed payment plan for a
certain period of 12 years or more (Plan 1) or any fixed payment plan which
involves a life contingency (Plans 2 or 3) if you select the payment plan after
the Contract has been in force for at least one full year.

ENHANCED DEATH BENEFIT CHARGE On each Contract anniversary on which the enhanced
death benefit is in effect, we deduct from the Contract value a charge based on
the amount of the enhanced death benefit on the Contract Anniversary and the age
of the Annuitant when the Contract was issued. The charge is 0.10% of the amount
of the enhanced death benefit for issue age 45 or less, 0.20% for issue age
46-55, and 0.40% for issue age 56-65. This charge is for the risks we assume in
guaranteeing the enhanced death benefit. We deduct the charge from the Divisions
of the Account and the Guaranteed Interest Fund in proportion to the amounts you
have invested.

PREMIUM TAXES The Contracts provide for the deduction of applicable premium
taxes, if any, from purchase payments or from Contract benefits. Various
jurisdictions levy premium taxes. Premium taxes presently range from 0% to 1% of
total purchase payments. Many jurisdictions presently exempt from premium taxes
annuities such as the Contracts. As a matter of current practice, we do not
deduct premium taxes from purchase payments received under the

                                       20
<PAGE>   29

Contracts or from Contract benefits. However, we reserve the right to deduct
premium taxes in the future.

EXPENSES FOR THE PORTFOLIOS AND FUNDS The expenses borne by the Portfolios and
Funds in which the assets of the Account are invested are described in the
prospectuses for Northwestern Mutual Series Fund, Inc. and the Russell Insurance
Funds. See the prospectuses attached to this prospectus.

CONTRACTS ISSUED PRIOR TO MARCH 31, 2000 During the period prior to March 31,
2000 and after March 31, 1995 we issued both Front Load Contracts and Back Load
Contracts. For the Front Load Contracts the deduction for sales expenses is 4%
on the first $100,000, 2% on the next $400,000, 1% the next $500,000, and 0.5%
on purchase payments in excess of $1 million, based on total cumulative purchase
payments paid under the Contract. The charge against Accumulation Units for
mortality and expense risks is 0.4% of the assets of the Account, which we may
raise to a maximum rate of 0.75%. The charge against Annuity Units for mortality
and expense risks is zero, which we may raise to a maximum rate of 0.75%. For
the Back Load Contracts there is a surrender charge of 8% on the first $100,000
of purchase payments, 4% on the next $400,000, 2% on the next $500,000, and 1%
on purchase payments in excess of $1 million, based on total cumulative purchase
payments paid under the Contract. The surrender charge applicable for each
purchase payment reduces by 1% on each Contract anniversary. A withdrawal charge
free amount is available, but the amount is limited by the excess of the
Contract value over the cumulative purchase payments on the date of the
withdrawal. The charge for mortality and expense risks for these Contracts is
1.25% of the assets of the Account, which we may raise to a maximum annual rate
of 1.50%. The Annual Contract fee is $30. We currently waive the Contract fee if
the Contract value is $50,000 or more.

CONTRACTS ISSUED PRIOR TO MARCH 31, 1995 For Contracts issued prior to March 31,
1995 and after December 16, 1981 there is no front-end sales load but there is a
surrender charge of 8% on the first $25,000 of purchase payments, 4% on the next
$75,000 and 2% on purchase payments in excess of $100,000, based on total
cumulative purchase payments paid under the Contract. The surrender charge
applicable for each purchase payment reduces by 1% on each Contract anniversary.
A withdrawal charge free amount is available, but the amount is limited by the
excess of the Contract value over the cumulative purchase payments on the date
of the withdrawal. The charge for mortality and expense risks for those
Contracts is 1.25% of the assets of the Account. The annual Contract fee is the
lesser of $30 or 1% of the Contract value. See the table of accumulation unit
values on page 9.

CONTRACTS ISSUED PRIOR TO DECEMBER 17, 1981 For Contracts issued prior to
December 17, 1981 there is no surrender charge, but purchase payments are
subject to a deduction for sales expenses. The deduction is 8% on the first
$5,000 received during a single Contract year as defined in the Contract, 4% on
the next $20,000, 2% on the next $75,000 and 1% on the excess over $100,000. The
charge for mortality and expense risks for these Contracts is 0.75% of the
assets of the Account, which we may raise to a maximum annual rate of 1%. There
is no annual Contract fee. See the table of accumulation unit values on page 11.

DIVIDENDS FOR CONTRACTS ISSUED PRIOR TO MARCH 31, 2000 During the year 2000 we
are paying dividends on approximately 20% of the in-force variable annuity
Contracts we issued prior to March 31, 2000. Dividends are not guaranteed to be
paid in future years. The dividend amount is volatile since it is based on the
average variable Contract value which is defined as the value of the
Accumulation units on the last Contract anniversary adjusted to reflect any
transactions since that date which increased or decreased the Contract's
interest in the Account.

Dividends on these variable annuities arise principally as a result of more
favorable expense experience than that which we assumed in determining
deductions. Such favorable experience is generated primarily by older and/or
larger Contracts, which have a mortality and expense risk charge of at least
0.75%. In general, we are not paying dividends on Contracts with an average
variable Contract value of less than $30,000, and about 75% of those with a
value above $30,000 will receive dividends. The expected dividend payout for the
year 2000 represents about 0.39% of the average variable Contract value for
those Contracts that will receive dividends. The maximum dividend we are paying
on a specific contract is about 0.70%.

We pay any dividend for a Contract on the anniversary date of that Contract. We
apply the dividend as a net purchase payment unless you elect to have the
dividend paid in cash.

REDUCED CHARGES FOR EXCHANGE TRANSACTIONS As a matter of current practice, we
permit owners of fixed dollar annuities we have previously issued to exchange
those contracts for Front Load or Back Load Contracts without paying a second
charge for sales expenses. This rule is subject to a number of exceptions and
qualifications. We may change or withdraw it at any time.

In general, we make a $25 administrative charge on these exchange transactions
and we permit only one such transaction in any 12-month period. Transactions on
this basis are subject to a limit of 20% of the amount held under the fixed
annuity contract in any 12-month period, but we are presently waiving this
limit.

Amounts exchanged from a fixed contract which provides for a surrender charge
are not charged for sales expenses when the exchange is effected. We place these
amounts in the same withdrawal charge category under the new Back Load Contract
as they were before.

                                       21

<PAGE>   30

We place exchange proceeds from fixed contracts which have no surrender charge
provisions in the 0% withdrawal charge category. As an alternative, exchange
proceeds from such a fixed contract may be added to a Front Load Contract or to
a Deferred Contract issued prior to December 17, 1981 without any deduction for
sales expenses.

Fixed annuity contracts (which are not described in this prospectus) are
available in exchange for the Contracts on a comparable basis.

- --------------------------------------------------------------------------------
DISTRIBUTION OF THE CONTRACTS


We sell the Contracts through individuals who are licensed insurance agents
appointed by Northwestern Mutual and are registered representatives of
Northwestern Mutual Investment Services, LLC, our wholly-owned subsidiary.
Northwestern Mutual Investment Services, LLC is located at 720 East Wisconsin
Avenue, Milwaukee, Wisconsin 53202. Northwestern Mutual Investment Services, LLC
is a registered broker-dealer under the Securities Exchange Act of 1934, and a
member of the National Association of Securities Dealers. Where state law
requires, these agents will also be licensed securities salesmen. Commissions
paid to the agents on sales of the Contracts will not exceed 4% of purchase
payments.



                                       22
<PAGE>   31


            TABLE OF CONTENTS FOR STATEMENT OF ADDITIONAL INFORMATION

<TABLE>
<CAPTION>
                                               PAGE
                                               ----
<S>                                            <C>
DISTRIBUTION OF THE
  CONTRACTS.....................................B-2
DETERMINATION OF ANNUITY
  PAYMENTS......................................B-2
    Amount of Annuity Payments..................B-2
    Annuity Unit Value..........................B-3
    Illustrations of Variable Annuity
      Payments..................................B-3
VALUATION OF ASSETS OF THE
  ACCOUNT.......................................B-4
TRANSFERABILITY RESTRICTIONS....................B-4
EXPERTS.........................................B-4
</TABLE>


<TABLE>
<CAPTION>
                                               PAGE
                                               ----
<S>                                            <C>
FINANCIAL STATEMENTS OF THE
  ACCOUNT (for the two years ended
   December 31, 1999)...........................B-5
REPORT OF INDEPENDENT
  ACCOUNTANTS (for the two
  years ended December 31, 1999)...............B-17
FINANCIAL STATEMENTS OF
  NORTHWESTERN MUTUAL
   (for the three years ended
   December 31, 1999)..........................B-18
REPORT OF INDEPENDENT
  ACCOUNTANTS (for the three years
   ended December 31, 1999)....................B-29
</TABLE>




     This Prospectus sets forth concisely the information about NML Variable
Annuity Account A that a prospective investor ought to know before investing.
Additional information about Account A has been filed with the Securities and
Exchange Commission in a Statement of Additional Information which is
incorporated herein by reference. The Statement of Additional Information is
available upon request and without charge from The Northwestern Mutual Life
Insurance Company. To receive a copy, return the request form to the address
listed below, or telephone 1-888-455-2232.




     TO:  The Northwestern Mutual Life Insurance Company

         Annuity and Accumulation Products Marketing Department
            Room E12J
         720 East Wisconsin Avenue
         Milwaukee, WI 53202

       Please send a Statement of Additional Information for NML Variable
       Annuity Account A to:

       Name
           ---------------------------------------------------------------------
       Address
              ------------------------------------------------------------------

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

       City                                State              Zip
           --------------------------------     --------------   ---------------



<PAGE>   32


More information about Northwestern Mutual Series Fund, Inc. is included in the
Fund's Statement of Additional Information (SAI), incorporated by reference in
this prospectus, which is available free of charge.

More information about the Fund's investments is included in the Fund's annual
and semi-annual reports, which discuss the market conditions and investment
strategies that significantly affected each Portfolio's performance during the
previous fiscal period.


To request a free copy of the Fund's SAI, or current annual or semi-annual
report, call us at 1-888-455-2232. Information about the Fund (including the
SAI) can be reviewed and copied at the Public Reference Room of the Securities
and Exchange Commission (SEC) in Washington, DC. Information on the operation of
the Public Reference Room may be obtained by calling the SEC at 1-800-SEC-0330.
Reports and other information about the Fund are available on the SEC's Internet
site at http://www.sec.gov. Copies of this information may be obtained, upon
payment of a duplicating fee, by writing the Public Reference Section of the
SEC, Washington, DC 20549-6009.


N O R T H W E S T E R N  M U T U A L  L I F E

INDIVIDUAL VARIABLE ANNUITY CONTRACTS
for Retirement Plans of Self-Employed Persons
and Their Employees


NML VARIABLE ANNUITY ACCOUNT A

NORTHWESTERN MUTUAL SERIES FUND, INC.

RUSSELL INSURANCE FUNDS

P    R    O    S    P    E    C    T    U    S


Investment Company Act File Nos. 811-3990 and 811-5371


NORTHWESTERN
MUTUAL LIFE(R)

PO Box 3095
Milwaukee  WI  53201-3095

Change Service Requested
<PAGE>   33
                       STATEMENT OF ADDITIONAL INFORMATION


                           VARIABLE ANNUITY CONTRACTS
       (for Retirement Plans of Self-Employed Persons and their Employees)


                         NML VARIABLE ANNUITY ACCOUNT A
                                (the "Account"),
                        a separate investment account of
                 The Northwestern Mutual Life Insurance Company
                             ("Northwestern Mutual")


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


                  This Statement of Additional Information is not a prospectus
                  but supplements and should be read in conjunction with the
                  prospectus for the Contracts. A copy of the prospectus may be
                  obtained from The Northwestern Mutual Life Insurance Company,
                  720 East Wisconsin Avenue, Milwaukee, Wisconsin 53202,
                  telephone number (414) 271-1444.


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

                  The Date of the Prospectus to which this Statement of
                  Additional Information Relates is March 31, 2000.

                  The Date of this Statement of Additional Information is March
                  31, 2000.


                                      B-1

<PAGE>   34


                          DISTRIBUTION OF THE CONTRACTS


      The Contracts are offered on a continuous basis exclusively through
individuals who, in addition to being life insurance agents of Northwestern
Mutual, are registered representatives of Northwestern Mutual Investment
Services, LLC ("NMIS").


      NMIS may be considered the underwriter of the Contracts for purposes of
the federal securities laws. The following amounts of commissions were paid on
sales of the Contracts, including commissions on sales of variable annuity
contracts to corporate pension plans, during each of the last three years:

<TABLE>
<CAPTION>
                        Year                      Amount
                        ----                      ------
<S>                     <C>                     <C>
                        1999                    $2,679,128
                        1998                    $2,760,049
                        1997                    $2,203,105

</TABLE>

                        DETERMINATION OF ANNUITY PAYMENTS

      The following discussion of the method for determining the amount of
monthly annuity payments under a variable payment plan is intended to be read in
conjunction with these sections of the prospectus for the Contracts: "Variable
Payment Plans", p. 15, including "Description of Payment Plans", p. 15, "Amount
of Annuity Payments", p. 15, and "Assumed Investment Rate", p. 15; "Dividends",
p. 16; "Net Investment Factor", p. 14; and "Deductions", p. 19.

      AMOUNT OF ANNUITY PAYMENTS The amount of the first annuity payment under a
variable Payment Plan will be determined on the basis of the particular Payment
Plan selected, the annuity payment rate and, for plans involving life
contingencies, the Annuitant's adjusted age. The amount of the first payment is
the sum of the payments from each Division of the Account determined by applying
the appropriate annuity payment rate to the product of the number of
Accumulation Units in the Division on the effective date of the Payment Plan and
the Accumulation Unit value for the Division on that date. Annuity rates
currently in use are based on the 1983 a Table with age adjustment.


      Variable annuity payments after the first will vary from month to month
and will depend upon the number and value of Annuity Units credited to the
Annuitant. After the effective date of a Payment Plan a Contract will not share
in the divisible surplus of Northwestern Mutual.


      The number of Annuity Units in each Division is determined by dividing the
amount of the first annuity payment from the Division by the value of an Annuity
Unit on the effective date of the Payment Plan. The number of Annuity Units thus
credited to the Annuitant in each Division remains constant throughout the
annuity period. However, the value of Annuity Units in each Division will
fluctuate with the investment experience of the Division.

      The amount of each variable annuity payment after the first is the sum of
payments from each Division determined by multiplying this fixed number of
Annuity Units each month by the value of an Annuity Unit for the Division on (a)
the fifth valuation date prior to the payment due date if the payment due date
is a valuation date, or (b) the sixth valuation date prior to the payment due
date if the payment due date is not a valuation date. To illustrate, if a
payment due date falls on a Friday, Saturday or Sunday, the amount of the
payment will normally be based upon the Annuity Unit value calculated on the
preceding Friday. The preceding Friday would be the fifth valuation date prior
to the Friday due date, and the sixth valuation date prior to the Saturday or
Sunday due dates.





                                      B-2
<PAGE>   35


         ANNUITY UNIT VALUE The value of an Annuity Unit for each Division was
established at $1.00 as of the date operations began for that Division. The
value of an Annuity Unit on any later date varies to reflect the investment
experience of the Division, the Assumed Investment Rate on which the annuity
rate tables are based, and the deduction for mortality rate and expense risks
assumed by Northwestern Mutual.


         The Annuity Unit value for each Division on any valuation date is
determined by multiplying the Annuity Unit value on the immediately preceding
valuation date by two factors: (a) the net investment factor for the current
period for the Division; and (b) an adjustment factor to neutralize the Assumed
Investment Rate used in calculating the annuity rate tables.

         ILLUSTRATIONS OF VARIABLE ANNUITY PAYMENTS To illustrate the manner in
which variable annuity payments are determined consider this example. Item (4)
in the example shows the applicable monthly payment rate for an annuitant,
adjusted age 65, who has elected a life annuity Payment Plan with a certain
period of 10 years with an Assumed Investment Rate of 3-1/2% (Plan 2, as
described in the prospectus). The example is for a Contract with sex-distinct
rates.

<TABLE>

<S>                                                                                          <C>
         (1)      Assumed number of Accumulation Units in
                  Balanced Division on maturity date .......................................  25,000

         (2)      Assumed Value of an Accumulation Unit in
                  Balanced Division at maturity.............................................  $2.000000

         (3)      Cash Value of Contract at maturity, (1) X (2).............................  $50,000

         (4)      Assumed applicable monthly payment rate per
                  $1,000 from annuity rate table............................................  $5.35

         (5)      Amount of first payment from Balanced Division,
                  (3) X (4) divided by $1,000...............................................  $267.50

         (6)      Assumed Value of Annuity Unit in
                  Balanced Division at maturity.............................................  $1.500000

         (7)      Number of Annuity Units credited in
                  Balanced Division, (5) divided by (6).....................................  178.33
</TABLE>

The $50,000 value at maturity provides a first payment from the Balanced
Division of $267.50, and payments thereafter of the varying dollar value of
178.33 Annuity Units. The amount of subsequent payments from the Balanced
Division is determined by multiplying 178.33 units by the value of an Annuity
Unit in the Balanced Division on the applicable valuation date. For example, if
that unit value is $1.501000, the monthly payment from the Division will be
178.33 multiplied by $1.501000, or $267.68.

         However, the value of the Annuity Unit depends entirely on the
investment performance of the Division. Thus in the example above, if the net
investment rate for the following month was less than the Assumed Investment
Rate of 3-1/2%, the Annuity Unit would decline in value. If the Annuity Unit
value declined to $1.499000 the succeeding monthly payment would then be 178.33
X $1.499000, or $267.32.

         For the sake of simplicity the foregoing example assumes that all of
the Annuity Units are in the Balanced Division. If there are Annuity Units in
two or more Divisions, the annuity payment from each Division is calculated
separately, in the manner illustrated, and the total monthly payment is the sum
of the payments from the Divisions.




                                      B-3


<PAGE>   36

                       VALUATION OF ASSETS OF THE ACCOUNT


         The value of Portfolio or Fund shares held in each Division of the
Account at the time of each valuation is the redemption value of such shares at
such time. If the right to redeem shares of a Portfolio or Fund has been
suspended, or payment of redemption value has been postponed, for the sole
purpose of computing annuity payments the shares held in the Account (and
Annuity Units) may be valued at fair value as determined in good faith by the
Board of Trustees of Northwestern Mutual.


                          TRANSFERABILITY RESTRICTIONS


         Ownership of a Contract cannot be changed or the Contract sold,
assigned or pledged as collateral for a loan, or for any other purpose, to any
person other than Northwestern Mutual; except, that if the Owner of the Contract
is a trustee of an employee trust qualified under the Code, or the custodian of
a custodial account treated as such, it may transfer the Contract to a successor
trustee or custodian. In addition, the trustee or custodian, as well as the
employer under a qualified non-trusted pension plan, may assign the Contract to
an employee upon termination of employment.


                                     EXPERTS


         The financial statements of the Account as of December 31, 1999 and for
each of the two years in the period ended December 31, 1999 and of Northwestern
Mutual as of December 31, 1999 and 1998 and for each of the three years in the
period ended December 31, 1999 included in this Statement of Additional
Information have been so included in reliance on the reports of
PricewaterhouseCoopers LLP, independent accountants, given on the authority of
said firm as experts in auditing and accounting. PricewaterhouseCoopers LLP
provides audit services for the Account. The address of PricewaterhouseCoopers
LLP is 100 East Wisconsin Avenue, Suite 1500, Milwaukee, Wisconsin 53202.



                                      B-4

<PAGE>   37

NML VARIABLE ANNUITY ACCOUNT A
Statement of Assets and Liabilities
December 31, 1999
(in thousands)


<TABLE>
<CAPTION>

 <S>                                                             <C>         <C>
 ASSETS
   Investments at Market Value:
     Northwestern Mutual Series Fund, Inc.
       Small Cap Growth Stock
          2,702 shares (cost $4,384).........................    $  4,847
       Aggressive Growth Stock
          21,708 shares (cost $63,877).......................     104,344
       International Equity
          25,519 shares (cost $39,067).......................      45,439
       Index 400 Stock
          1,981 shares (cost $2,051).........................       2,205
       Growth Stock
          14,699 shares (cost $29,389).......................      39,031
       Growth and Income Stock
          22,898 shares (cost $34,015).......................      35,735
       Index 500 Stock
          43,711 shares (cost $89,440).......................     169,861
       Balanced
          143,907 shares (cost $230,277).....................     319,678
       High Yield Bond
          8,444 shares (cost $8,362).........................       6,940
       Select Bond
          19,599 shares (cost $23,331).......................      22,162
       Money Market
          28,967 shares (cost $28,967).......................      28,975
     Russell Insurance Funds
       Multi-Style Equity
          148 shares (cost $2,438)...........................       2,500
       Aggressive Equity
          85 shares (cost $1,024)............................       1,142
       Non-U.S.
          98 shares (cost $1,229)............................       1,383
       Real Estate Securities
          38 shares (cost $342)..............................         332
       Core Bond
          72 shares (cost $716)..............................         693    $785,267
                                                                 --------
   Due from Sale of Fund Shares..............................                   1,329
   Due from Northwestern Mutual Life Insurance Company.......                   1,012
                                                                             --------
            Total Assets.....................................                $787,608
                                                                             ========

 LIABILITIES
   Due to Participants.......................................                $  1,063
   Due to Northwestern Mutual Life Insurance Company.........                   1,329
   Due on Purchase of Fund Shares............................                   1,012
                                                                             --------
            Total Liabilities................................                   3,404
                                                                             --------

 EQUITY (NOTE 8)
   Contracts Issued Prior to December 17, 1981...............                  74,251
   Contracts Issued After December 16, 1981 and Prior to
     March 31, 1995..........................................                 584,436
   Contracts Issued On or After March 31, 1995:
     Front Load Version......................................                  20,716
     Back Load Version.......................................                 104,801
                                                                             --------
            Total Equity.....................................                 784,204
                                                                             --------
            Total Liabilities and Equity.....................                $787,608
                                                                             ========
</TABLE>


    The Accompanying Notes are an Integral Part of the Financial Statements

                                      B- 5        Account A Financial Statements
<PAGE>   38

NML VARIABLE ANNUITY ACCOUNT A
Statement of Operations
(in thousands)


<TABLE>
<CAPTION>
                                                                                    SMALL CAP
                                                                                   GROWTH STOCK           AGGRESSIVE GROWTH
                                                           COMBINED                 DIVISION#               STOCK DIVISION
                                                 ----------------------------      ------------      ----------------------------
                                                                                   EIGHT MONTHS
                                                  YEAR ENDED      YEAR ENDED          ENDED           YEAR ENDED      YEAR ENDED
                                                 DECEMBER 31,    DECEMBER 31,      DECEMBER 31,      DECEMBER 31,    DECEMBER 31,
                                                     1999            1998              1999              1999            1998
- ---------------------------------------------------------------------------------------------------------------------------------
<S>                                              <C>             <C>               <C>               <C>             <C>
INVESTMENT INCOME
  Dividend Income............................      $ 56,817        $ 34,233           $  149           $ 2,871         $ 3,294
  Annuity Rate and Expense Guarantees........         8,722           8,067               13             1,001           1,049
                                                   --------        --------           ------           -------         -------
  Net Investment Income (Loss)...............        48,095          26,166              136             1,870           2,245
                                                   --------        --------           ------           -------         -------

REALIZED AND UNREALIZED GAIN (LOSS) ON INVESTMENTS
  Realized Gain (Loss) on Investments........        51,300          37,625              550            10,360           6,752
  Unrealized Appreciation (Depreciation) of
    Investments During the Period............         9,270          36,250              464            18,776          (3,928)
                                                   --------        --------           ------           -------         -------
  Net Gain (Loss) on Investments.............        60,570          73,875            1,014            29,136           2,824
                                                   --------        --------           ------           -------         -------
  Increase (Decrease) in Equity Derived from
    Investment Activity......................      $108,665        $100,041           $1,150           $31,006         $ 5,069
                                                   ========        ========           ======           =======         =======
</TABLE>



# The initial investment in this Division was made on April 30, 1999.


    The Accompanying Notes are an Integral Part of the Financial Statements

Account A Financial Statements        B- 6
<PAGE>   39

<TABLE>
<CAPTION>
                                    INDEX 400
                                      STOCK                                            GROWTH & INCOME
 INTERNATIONAL EQUITY DIVISION      DIVISION#         GROWTH STOCK DIVISION            STOCK DIVISION
- -------------------------------   --------------   ---------------------------   ---------------------------
                                   EIGHT MONTHS
     YEAR ENDED     YEAR ENDED        ENDED         YEAR ENDED     YEAR ENDED     YEAR ENDED     YEAR ENDED
    DECEMBER 31,   DECEMBER 31,    DECEMBER 31,    DECEMBER 31,   DECEMBER 31,   DECEMBER 31,   DECEMBER 31,
        1999           1998            1999            1999           1998           1999           1998
- ------------------------------------------------------------------------------------------------------------
<S> <C>            <C>            <C>              <C>            <C>            <C>            <C>
       $6,194        $ 2,855           $ 30           $1,225         $  461        $ 4,191         $  294
          520            591              8              397            263            442            353
       ------        -------           ----           ------         ------        -------         ------
        5,674          2,264             22              828            198          3,749            (59)
       ------        -------           ----           ------         ------        -------         ------

        2,516          3,000             18            2,300          1,743          1,705          1,022
          193         (3,655)           154            3,411          2,872         (3,315)         4,954
       ------        -------           ----           ------         ------        -------         ------
        2,709           (655)           172            5,711          4,615         (1,610)         5,976
       ------        -------           ----           ------         ------        -------         ------
       $8,383        $ 1,609           $194           $6,539         $4,813        $ 2,139         $5,917
       ======        =======           ====           ======         ======        =======         ======

<CAPTION>

              INDEX 500
 IN        STOCK DIVISION
- ---  ---------------------------

      YEAR ENDED     YEAR ENDED
     DECEMBER 31,   DECEMBER 31,
         1999           1998
- ---  ---------------------------
<S>  <C>            <C>
       $ 3,676        $ 4,267
         1,766          1,404
       -------        -------
         1,910          2,863
       -------        -------
        13,204          8,567
        13,045         18,919
       -------        -------
        26,249         27,486
       -------        -------
       $28,159        $30,349
       =======        =======
</TABLE>


                                      B- 7        Account A Financial Statements
<PAGE>   40

NML VARIABLE ANNUITY ACCOUNT A
Statement of Operations

(in thousands)

<TABLE>
<CAPTION>

                                          BALANCED DIVISION            HIGH YIELD BOND DIVISION          SELECT BOND DIVISION
                                     ----------------------------    ----------------------------    ----------------------------
                                      YEAR ENDED      YEAR ENDED      YEAR ENDED      YEAR ENDED      YEAR ENDED      YEAR ENDED
                                     DECEMBER 31,    DECEMBER 31,    DECEMBER 31,    DECEMBER 31,    DECEMBER 31,    DECEMBER 31,
            (CONTINUED)                  1999            1998            1999            1998            1999            1998
- ---------------------------------------------------------------------------------------------------------------------------------
<S>                                  <C>             <C>             <C>             <C>             <C>             <C>
INVESTMENT INCOME
  Dividend Income..................    $ 34,011        $19,089          $ 821          $   951         $ 2,088          $1,768
  Annuity Rate and Expense
    Guarantees.....................       3,881          3,750             94              113             265             277
                                       --------        -------          -----          -------         -------          ------
  Net Investment Income (Loss).....      30,130         15,339            727              838           1,823           1,491
                                       --------        -------          -----          -------         -------          ------

REALIZED AND UNREALIZED GAIN (LOSS)
  ON INVESTMENTS
  Realized Gain (Loss) on
    Investments....................      21,154         16,661           (847)            (220)            370             100
  Unrealized Appreciation
    (Depreciation) of Investments
    During the Period..............     (21,022)        18,160            (22)            (925)         (2,715)           (147)
                                       --------        -------          -----          -------         -------          ------
  Net Gain (Loss) on Investments...         132         34,821           (869)          (1,145)         (2,345)            (47)
                                       --------        -------          -----          -------         -------          ------
  Increase (Decrease) in Equity
    Derived from Investment
    Activity.......................    $ 30,262        $50,160          $(142)         $  (307)        $  (522)         $1,444
                                       ========        =======          =====          =======         =======          ======
</TABLE>



# The initial investment in this Division was made on April 30, 1999.


    The Accompanying Notes are an Integral Part of the Financial Statements

Account A Financial Statements        B- 8
<PAGE>   41


<TABLE>
<CAPTION>
                                                                                            RUSSELL
                                      RUSSELL            RUSSELL           RUSSELL        REAL ESTATE        RUSSELL
                                    MULTI-STYLE         AGGRESSIVE         NON-U.S.        SECURITIES       CORE BOND
                                  EQUITY DIVISION#   EQUITY DIVISION#     DIVISION#        DIVISION#        DIVISION#
     MONEY MARKET DIVISION        ----------------   ----------------   --------------   --------------   --------------
- -------------------------------     EIGHT MONTHS       EIGHT MONTHS      EIGHT MONTHS     EIGHT MONTHS     EIGHT MONTHS
     YEAR ENDED     YEAR ENDED         ENDED              ENDED             ENDED            ENDED            ENDED
    DECEMBER 31,   DECEMBER 31,     DECEMBER 31,       DECEMBER 31,      DECEMBER 31,     DECEMBER 31,     DECEMBER 31,
        1999           1998             1999               1999              1999             1999             1999
- ------------------------------------------------------------------------------------------------------------------------
<S> <C>            <C>            <C>                <C>                <C>              <C>              <C>
       $1,410         $1,254            $ 76               $  4              $ 37             $ 12             $ 22
          315            267               9                  4                 4                1                2
       ------         ------            ----               ----              ----             ----             ----
        1,095            987              67                 --                33               11               20
       ------         ------            ----               ----              ----             ----             ----

           --             --              (3)               (34)               10               (2)              (1)
           --             --              62                118               154              (10)             (23)
       ------         ------            ----               ----              ----             ----             ----
           --             --              59                 84               164              (12)             (24)
       ------         ------            ----               ----              ----             ----             ----
       $1,095         $  987            $126               $ 84              $197             $ (1)            $ (4)
       ======         ======            ====               ====              ====             ====             ====
</TABLE>


                                      B- 9        Account A Financial Statements
<PAGE>   42

NML VARIABLE ANNUITY ACCOUNT A
Statement of Changes in Equity
(in thousands)


<TABLE>
<CAPTION>
                                                                                    SMALL CAP
                                                                                   GROWTH STOCK           AGGRESSIVE GROWTH
                                                           COMBINED                 DIVISION#               STOCK DIVISION
                                                 ----------------------------      ------------      ----------------------------
                                                                                   EIGHT MONTHS
                                                  YEAR ENDED      YEAR ENDED          ENDED           YEAR ENDED      YEAR ENDED
                                                 DECEMBER 31,    DECEMBER 31,      DECEMBER 31,      DECEMBER 31,    DECEMBER 31,
                                                     1999            1998              1999              1999            1998
- ---------------------------------------------------------------------------------------------------------------------------------
<S>                                              <C>             <C>               <C>               <C>             <C>
OPERATIONS
  Net Investment Income......................     $  48,095        $ 26,166          $   136           $  1,870        $  2,245
  Net Realized gain (loss)...................        51,300          37,625              550             10,360           6,752
  Net Change in unrealized appreciation
    (depreciation)...........................         9,270          36,250              464             18,776          (3,928)
                                                  ---------        --------          -------           --------        --------
Increase (Decrease) in Equity Derived from
  Investment Activity........................       108,665         100,041            1,150             31,006           5,069
                                                  ---------        --------          -------           --------        --------

EQUITY TRANSACTIONS
  Contract Owners' Net Payments..............        55,489          62,325              398              6,945          10,359
  Annuity Payments...........................        (1,469)         (1,306)              --                (36)            (41)
  Surrenders and Other (net).................      (102,935)        (80,848)             (85)           (12,324)         (8,661)
  Transfers from Other Divisions or
    Sponsor..................................       125,332          95,967            7,491             13,400           8,930
  Transfers to Other Divisions or Sponsor....      (126,511)        (98,941)          (4,107)           (22,500)        (17,180)
                                                  ---------        --------          -------           --------        --------
Increase (Decrease) in Equity Derived from
  Equity Transactions........................       (50,094)        (22,803)           3,697            (14,515)         (6,593)
                                                  ---------        --------          -------           --------        --------
Net Increase (Decrease) in Equity............        58,571          77,238            4,847             16,491          (1,524)

EQUITY
  Beginning of Period........................       725,633         648,395               --             87,879          89,403
                                                  ---------        --------          -------           --------        --------
  End of Period..............................     $ 784,204        $725,633          $ 4,847           $104,370        $ 87,879
                                                  =========        ========          =======           ========        ========
</TABLE>



# The initial investment in this Division was made on April 30, 1999.


    The Accompanying Notes are an Integral Part of the Financial Statements

Account A Financial Statements       B- 10
<PAGE>   43

<TABLE>
<CAPTION>
                                    INDEX 400
                                      STOCK                                            GROWTH & INCOME
 INTERNATIONAL EQUITY DIVISION      DIVISION#         GROWTH STOCK DIVISION            STOCK DIVISION
- -------------------------------   --------------   ---------------------------   ---------------------------
                                   EIGHT MONTHS
     YEAR ENDED     YEAR ENDED        ENDED         YEAR ENDED     YEAR ENDED     YEAR ENDED     YEAR ENDED
    DECEMBER 31,   DECEMBER 31,    DECEMBER 31,    DECEMBER 31,   DECEMBER 31,   DECEMBER 31,   DECEMBER 31,
        1999           1998            1999            1999           1998           1999           1998
- ------------------------------------------------------------------------------------------------------------
<S> <C>            <C>            <C>              <C>            <C>            <C>            <C>
      $ 5,674        $  2,264         $   22         $   828        $   198        $ 3,749        $   (59)
        2,516           3,000             18           2,300          1,743          1,705          1,022
          193          (3,655)           154           3,411          2,872         (3,315)         4,954
      -------        --------         ------         -------        -------        -------        -------
        8,383           1,609            194           6,539          4,813          2,139          5,917
      -------        --------         ------         -------        -------        -------        -------

        3,455           4,941            410           3,966          3,618          3,728          4,697
          (25)            (32)            --              (6)            (4)           (71)           (55)
       (6,125)         (5,289)           (93)         (3,594)        (2,367)        (3,578)        (2,704)
        3,673           5,056          2,621          13,108          7,949          8,139          9,679
       (8,861)        (11,484)          (937)         (7,589)        (4,660)       (10,849)        (4,854)
      -------        --------         ------         -------        -------        -------        -------
       (7,883)         (6,808)         2,001           5,885          4,536         (2,631)         6,763
      -------        --------         ------         -------        -------        -------        -------
          500          (5,199)         2,195          12,424          9,349           (492)        12,680

       44,912          50,111             --          26,604         17,255         36,228         23,548
      -------        --------         ------         -------        -------        -------        -------
      $45,412        $ 44,912         $2,195         $39,028        $26,604        $35,736        $36,228
      =======        ========         ======         =======        =======        =======        =======

<CAPTION>

              INDEX 500
 IN        STOCK DIVISION
- ---  ---------------------------

      YEAR ENDED     YEAR ENDED
     DECEMBER 31,   DECEMBER 31,
         1999           1998
- ---  ---------------------------
<S>  <C>            <C>
       $  1,910       $  2,863
         13,204          8,567
         13,045         18,919
       --------       --------
         28,159         30,349
       --------       --------
         11,822         11,699
           (489)          (411)
        (19,188)       (12,885)
         24,383         17,648
        (18,154)       (14,119)
       --------       --------
         (1,626)         1,932
       --------       --------
         26,533         32,281
        143,176        110,895
       --------       --------
       $169,709       $143,176
       ========       ========
</TABLE>


                                     B- 11        Account A Financial Statements
<PAGE>   44

NML VARIABLE ANNUITY ACCOUNT A
Statement of Changes in Equity
(in thousands)


<TABLE>
<CAPTION>

                                          BALANCED DIVISION            HIGH YIELD BOND DIVISION          SELECT BOND DIVISION
                                     ----------------------------    ----------------------------    ----------------------------
                                      YEAR ENDED      YEAR ENDED      YEAR ENDED      YEAR ENDED      YEAR ENDED      YEAR ENDED
                                     DECEMBER 31,    DECEMBER 31,    DECEMBER 31,    DECEMBER 31,    DECEMBER 31,    DECEMBER 31,
            (CONTINUED)                  1999            1998            1999            1998            1999            1998
- ---------------------------------------------------------------------------------------------------------------------------------
<S>                                  <C>             <C>             <C>             <C>             <C>             <C>
OPERATIONS
  Net Investment Income............   $   30,130      $   15,339       $    727        $    838        $  1,823        $  1,491
  Net Realized gain (loss).........       21,154          16,661           (847)           (220)            370             100
  Net Change in unrealized
    appreciation (depreciation)....      (21,022)         18,160            (22)           (925)         (2,715)           (147)
                                      ----------      ----------       --------        --------        --------        --------
Increase (Decrease) in Equity
  Derived from Investment
  Activity.........................       30,262          50,160           (142)           (307)           (522)          1,444
                                      ----------      ----------       --------        --------        --------        --------

EQUITY TRANSACTIONS
  Contract Owners' Net Payments....       15,663          17,160            989           2,104           1,638           2,145
  Annuity Payments.................         (742)           (662)            (5)             (5)            (55)            (59)
  Surrenders and Other (net).......      (45,409)        (35,226)        (1,234)           (806)         (4,343)         (3,234)
  Transfers from Other Divisions or
    Sponsor........................       17,537          10,851          1,293           4,761           2,826           3,443
  Transfers to Other Divisions or
    Sponsor........................      (23,181)        (19,108)        (3,220)         (5,233)         (3,264)         (3,102)
                                      ----------      ----------       --------        --------        --------        --------
Increase (Decrease) in Equity
  Derived from Equity
  Transactions.....................      (36,132)        (26,985)        (2,177)            821          (3,198)           (807)
                                      ----------      ----------       --------        --------        --------        --------
Net Increase (Decrease) in
  Equity...........................       (5,870)         23,175         (2,319)            514          (3,720)            637

EQUITY
  Beginning of Period..............      324,803         301,628          9,258           8,744          25,862          25,225
                                      ----------      ----------       --------        --------        --------        --------
  End of Period....................   $  318,933      $  324,803       $  6,939        $  9,258        $ 22,142        $ 25,862
                                      ==========      ==========       ========        ========        ========        ========
</TABLE>



# The initial investment in this Division was made on April 30, 1999.


    The Accompanying Notes are an Integral Part of the Financial Statements

Account A Financial Statements       B- 12
<PAGE>   45


<TABLE>
<CAPTION>
                                                                                            RUSSELL
                                      RUSSELL            RUSSELL           RUSSELL        REAL ESTATE        RUSSELL
                                    MULTI-STYLE         AGGRESSIVE         NON-U.S.        SECURITIES       CORE BOND
                                  EQUITY DIVISION#   EQUITY DIVISION#     DIVISION#        DIVISION#        DIVISION#
     MONEY MARKET DIVISION        ----------------   ----------------   --------------   --------------   --------------
- -------------------------------     EIGHT MONTHS       EIGHT MONTHS      EIGHT MONTHS     EIGHT MONTHS     EIGHT MONTHS
     YEAR ENDED     YEAR ENDED         ENDED              ENDED             ENDED            ENDED            ENDED
    DECEMBER 31,   DECEMBER 31,     DECEMBER 31,       DECEMBER 31,      DECEMBER 31,     DECEMBER 31,     DECEMBER 31,
        1999           1998             1999               1999              1999             1999             1999
- ------------------------------------------------------------------------------------------------------------------------
<S> <C>            <C>            <C>                <C>                <C>              <C>              <C>
      $  1,095       $    987          $   67             $   --            $   33            $ 11             $ 20
            --             --              (3)               (34)               10              (2)              (1)
            --             --              62                118               154             (10)             (23)
      --------       --------          ------             ------            ------            ----             ----
         1,095            987             126                 84               197              (1)              (4)
      --------       --------          ------             ------            ------            ----             ----

         5,147          5,602             750                285               189              33               71
           (40)           (37)             --                 --                --              --               --
        (6,872)        (9,676)            (36)               (22)              (31)             (1)              --
        24,985         27,650           1,993              1,498             1,372             324              689
       (22,381)       (19,201)           (333)              (703)             (344)            (24)             (64)
      --------       --------          ------             ------            ------            ----             ----
           839          4,338           2,374              1,058             1,186             332              696
      --------       --------          ------             ------            ------            ----             ----
         1,934          5,325           2,500              1,142             1,383             331              692

        26,911         21,586              --                 --                --              --               --
      --------       --------          ------             ------            ------            ----             ----
      $ 28,845       $ 26,911          $2,500             $1,142            $1,383            $331             $692
      ========       ========          ======             ======            ======            ====             ====
</TABLE>


                                     B- 13        Account A Financial Statements
<PAGE>   46


NML VARIABLE ANNUITY ACCOUNT A


Notes to Financial Statements

December 31, 1999

NOTE 1 -- NML Variable Annuity Account A (the "Account") is a segregated asset
account of The Northwestern Mutual Life Insurance Company ("Northwestern Mutual"
or "Sponsor") used to fund variable annuity contracts ("contracts") for HR-10
and corporate pension and profit-sharing plans which qualify for special tax
treatment under the Internal Revenue Code. Beginning March 31, 1995 two versions
of the contract are offered: Front Load contracts with a sales charge up to 4%
of purchase payments and Back Load contracts with a withdrawal charge of 0-8%.

NOTE 2 -- The preparation of the 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 at the date of the financial
statements and the reported amounts of revenues and expenses during the
reporting period. Actual results could differ from those estimates. Principal
accounting policies are summarized below.


NOTE 3 -- All assets of each Division of the Account are invested in shares of
the corresponding Portfolio of Northwestern Mutual Series Fund, Inc. and the
Russell Insurance Funds (collectively known as "the Funds"). The shares are
valued at the Funds' offering and redemption prices per share.



The Funds are open-end investment companies registered under the Investment
Company Act of 1940.


NOTE 4 -- Annuity reserves are based on published annuity tables with age
adjustment and benefit payments which reflect actual investment experience. For
variable payment plans issued prior to January 1, 1974, annuity reserves are
based on the 1955 American Annuity Table with assumed interest rates of 3% or
5%. For variable payment plans issued on or after January 1, 1974 and before
January 1, 1985, annuity reserves are based on the 1971 Individual Annuity Table
with assumed interest rates of 3 1/2% or 5%. For variable payment plans issued
on or after January 1, 1985, annuity reserves are based on the 1983 Table a with
assumed interest rates of 3 1/2% or 5%.


NOTE 5 -- Dividend income from the Funds is recorded on the record date of the
dividends. Transactions in the Funds shares are accounted for on the trade date.
The basis for determining cost on sale of the Funds shares is identified cost.
Purchases and sales of the Funds shares for the period ended December 31, 1999
by each Division are shown below:



<TABLE>
<CAPTION>
        DIVISIONS            PURCHASES       SALES
        ---------            ---------       -----
<S>                         <C>           <C>
Small Cap Growth Stock....  $ 7,208,705   $ 3,374,541
Aggressive Growth Stock...    9,958,208    22,717,778
International Equity......    7,974,310    10,228,782
Index 400 Stock...........    2,853,810       821,170
Growth Stock..............   11,793,727     5,237,895
Growth & Income Stock.....    9,919,814     9,006,288
Index 500 Stock...........   20,410,794    20,135,029
Balanced..................   44,419,512    50,211,717
High Yield Bond...........    2,095,955     3,579,846
Select Bond...............    4,931,954     6,390,659
Money Market..............   20,905,226    18,848,756
Russell Multi-Style Equity
  Fund....................    2,666,402       225,476
Russell Aggressive Equity
  Fund....................    1,593,605       535,192
Russell Non-U.S. Fund.....    1,498,221       279,802
Russell Real Estate
  Securities Fund.........      357,723        13,625
Russell Core Bond Fund....      758,431        41,756
</TABLE>


NOTE 6 -- A deduction for annuity rate and expense guarantees is determined
daily and paid to Northwestern Mutual as compensation for assuming the risk that
annuity payments will continue for longer periods than anticipated because the
annuitants as a group live longer than expected, and the risk that the charges
made by Northwestern Mutual may be insufficient to cover the actual costs
incurred in connection with the contracts.

For contracts issued on or after March 31, 1995, for the Front Load version and
the Back Load version, the deduction for annuity rate and expense guarantees is
determined daily at annual rates of 4/10 of 1% and 1 1/4%, respectively, of the
net assets of each Division attributable to these contracts and is paid to
Northwestern Mutual. For these contracts, the rates may be increased or
decreased by the Board of Trustees of Northwestern Mutual not to exceed 3/4 of
1% and 1 1/2%, respectively.

For contracts issued after December 16, 1981 and prior to March 31, 1995, the
deduction is at an annual rate of 1 1/4% of the net assets of each division
attributable to these contracts. For these contracts, the rate may be increased
or decreased by the Board of Trustees of Northwestern Mutual not to exceed a
1 1/2% annual rate.

Notes to Financial Statements        B- 14
<PAGE>   47

For contracts issued prior to December 17, 1981, the deduction is at an annual
rate of 3/4 of 1% of the net assets of each Division attributable to these
contracts. For these contracts, the rate may be increased or decreased by the
Board of Trustees of Northwestern Mutual not to exceed a 1% annual rate.

Since 1995, Northwestern Mutual has paid a dividend to certain contracts. The
dividend is re-invested in the Account and has been reflected as a Contract
Owners' Net Deposit in the accompanying financial statements.


NOTE 7 -- Northwestern Mutual is taxed as a "life insurance company" under the
Internal Revenue Code and the operations of the Account form a part of and are
taxed with those of Northwestern Mutual. Under current law, no federal income
taxes are payable with respect to the Account. Accordingly, no provision for any
such liability has been made.


                                     B- 15         Notes to Financial Statements
<PAGE>   48

NML VARIABLE ANNUITY ACCOUNT A
Notes to Financial Statements
December 31, 1999
(in thousands)

NOTE 8 -- Equity Values by Division are shown below:


<TABLE>
<CAPTION>
                                                                                                  CONTRACTS ISSUED:
                                                       CONTRACTS ISSUED:                     AFTER DECEMBER 16, 1981 AND
                                                   PRIOR TO DECEMBER 17, 1981                  PRIOR TO MARCH 31, 1995
                                             --------------------------------------    ---------------------------------------
                                             ACCUMULATION       UNITS                  ACCUMULATION       UNITS
                DIVISION                      UNIT VALUE     OUTSTANDING    EQUITY      UNIT VALUE     OUTSTANDING     EQUITY
- ------------------------------------------------------------------------------------------------------------------------------
<S>                                          <C>             <C>            <C>        <C>             <C>            <C>
Small Cap Growth Stock...................     $1.851783            95       $   176     $1.845580         1,899       $  3,505
Aggressive Growth Stock..................      5.658407           371         2,099      5.407959        14,666         79,313
International Equity.....................      2.375600           630         1,497      2.297694        15,308         35,173
Index 400 Stock..........................      1.122676           167           187      1.118909         1,241          1,389
Growth Stock.............................      3.099518           373         1,156      3.012947         8,576         25,839
Growth and Income Stock..................      2.600855           254           661      2.528256         9,503         24,026
Index 500 Stock..........................      5.043329         6,688        33,729      4.820195        20,901        100,747
Balanced.................................      8.136959         2,738        22,279      7.436406        35,440        263,546
High Yield Bond..........................      1.563339            77           120      1.519653         2,904          4,413
Select Bond..............................      7.582833           715         5,422      6.928532         1,915         13,268
Money Market.............................      2.760791           898         2,479      2.523294         7,330         18,496
Russell Multi-Style Equity...............      1.070614             8             9      1.067018         1,475          1,574
Russell Aggressive Equity................      1.103591             7             8      1.099895           761            837
Russell Non-U.S. ........................      1.247160            12            15      1.242993           814          1,012
Russell Real Estate Securities...........      0.922768             5             5      0.919674           249            229
Russell Core Bond........................      0.986452             3             3      0.983142           581            571
                                                                            -------                                   --------
  Equity.................................                                    69,845                                    573,938
  Annuity Reserves.......................                                     4,406                                     10,498
                                                                            -------                                   --------
  Total Equity...........................                                   $74,251                                   $584,436
                                                                            =======                                   ========
</TABLE>



<TABLE>
<CAPTION>
                                                       CONTRACTS ISSUED:                          CONTRACTS ISSUED:
                                                   ON OR AFTER MARCH 31, 1995                ON OR AFTER MARCH 31, 1995
                                                       FRONT LOAD VERSION                         BACK LOAD VERSION
                                             --------------------------------------    ---------------------------------------
                                             ACCUMULATION       UNITS                  ACCUMULATION       UNITS
                DIVISION                      UNIT VALUE     OUTSTANDING    EQUITY      UNIT VALUE     OUTSTANDING     EQUITY
- ------------------------------------------------------------------------------------------------------------------------------
<S>                                          <C>             <C>            <C>        <C>             <C>            <C>
Small Cap Growth Stock...................     $1.856086           150       $   278     $1.845580           481       $    888
Aggressive Growth Stock..................      2.661899         1,186         3,157      5.407959         3,585         19,388
International Equity.....................      1.964300           728         1,430      2.297694         3,063          7,038
Index 400 Stock..........................      1.125296           163           183      1.118909           388            434
Growth Stock.............................      2.898070           613         1,777      3.012947         3,382         10,190
Growth and Income Stock..................      2.431081           757         1,840      2.528256         3,307          8,361
Index 500 Stock..........................      3.127888         1,247         3,901      4.820195         5,418         26,115
Balanced.................................      2.117903         1,801         3,814      7.436406         2,897         21,543
High Yield Bond..........................      1.483036           381           565      1.519653         1,175          1,786
Select Bond..............................      1.331215           215           286      6.928532           364          2,522
Money Market.............................      1.259407         1,980         2,494      2.523294         1,893          4,777
Russell Multi-Style Equity...............      1.073107           322           346      1.067018           535            571
Russell Aggressive Equity................      1.106159            88            97      1.099895           183            201
Russell Non-U.S. ........................      1.250059            81           101      1.242993           205            255
Russell Real Estate Securities...........      0.924920            19            18      0.919674            88             81
Russell Core Bond........................      0.988747            27            27      0.983142            94             92
                                                                            -------                                   --------
  Equity.................................                                    20,314                                    104,242
  Annuity Reserves.......................                                       402                                        559
                                                                            -------                                   --------
  Total Equity...........................                                   $20,716                                   $104,801
                                                                            =======                                   ========
</TABLE>


Notes to Financial Statements        B- 16
<PAGE>   49

[PRICEWATERHOUSECOOPERS LLC - LETTERHEAD]


Report of Independent Accountants



To The Northwestern Mutual Life Insurance Company and


Contract Owners of NML Variable Annuity Account A



In our opinion, the accompanying combined statement of assets and liabilities
and the related combined and separate statements of operations and of changes in
equity present fairly, in all material respects, the financial position of NML
Variable Annuity Account A and the Small Cap Growth Stock Division, Aggressive
Growth Stock Division, International Equity Division, Index 400 Stock Division,
Growth Stock Division, Growth & Income Stock Division, Index 500 Stock Division,
Balanced Division, High Yield Bond Division, Select Bond Division, Money Market
Division, Russell Multi-Style Equity Division, Russell Aggressive Equity
Division, Russell Non-U.S. Division, Russell Real Estate Securities Division and
Russell Core Bond Division thereof at December 31, 1999, the results of each of
their operations for each of the two years or the period then ended and the
changes in each of their equity for the two years or the period then ended in
conformity with accounting principles generally accepted in the United States.
These financial statements are the responsibility of The Northwestern Mutual
Life Insurance Company's management; our responsibility is to express an opinion
on these financial statements based on our audits. We conducted our audits of
these financial statements in accordance with auditing standards generally
accepted in the United States which 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, assessing
the accounting principles used and significant estimates made by management, and
evaluating the overall financial statement presentation. We believe that our
audits, which included direct confirmation of the number of shares owned at
December 31, 1999 with Northwestern Mutual Series Fund, Inc. and the Russell
Insurance Funds, provide a reasonable basis for the opinion expressed above.


[PRICEWATERHOUSECOOPERS LLP]


Milwaukee, Wisconsin


January 27, 2000


                                     B- 17                   Accountants' Report
<PAGE>   50

THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
Consolidated Statement of Financial Position
(in millions)

The following financial statements of Northwestern Mutual should be considered
only as bearing upon the ability of Northwestern Mutual Life to meet its
obligations under the Policies.

<TABLE>
<CAPTION>
                                                                    DECEMBER 31,
                                                                ---------------------
                                                                 1999          1998
- -------------------------------------------------------------------------------------
<S>                                                             <C>           <C>
ASSETS
  Bonds.....................................................    $36,792       $34,888
  Common and preferred stocks...............................      7,108         6,062
  Mortgage loans............................................     13,416        12,250
  Real estate...............................................      1,666         1,481
  Policy loans..............................................      7,938         7,580
  Other investments.........................................      3,443         2,353
  Cash and temporary investments............................      1,159         1,275
                                                                -------       -------
    TOTAL INVESTMENTS.......................................     71,522        65,889
  Due and accrued investment income.........................        893           827
  Other assets..............................................      1,409         1,313
  Separate account assets...................................     12,161         9,966
                                                                -------       -------
    TOTAL ASSETS............................................    $85,985       $77,995
                                                                =======       =======
LIABILITIES AND SURPLUS
  Reserves for policy benefits..............................    $56,246       $51,815
  Policy benefit and premium deposits.......................      1,746         1,709
  Policyowner dividends payable.............................      3,100         2,870
  Interest maintenance reserve..............................        491           606
  Asset valuation reserve...................................      2,371         1,994
  Income taxes payable......................................      1,192         1,161
  Other liabilities.........................................      3,609         3,133
  Separate account liabilities..............................     12,161         9,966
                                                                -------       -------
    TOTAL LIABILITIES.......................................     80,916        73,254
  Surplus...................................................      5,069         4,741
                                                                -------       -------
    TOTAL LIABILITIES AND SURPLUS...........................    $85,985       $77,995
                                                                =======       =======
</TABLE>


   The Accompanying Notes are an Integral Part of these Financial Statements


Consolidated Statement of Financial Position
                                     B- 18
<PAGE>   51

THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
Consolidated Statement of Operations
(in millions)

<TABLE>
<CAPTION>
                                                              FOR THE YEAR ENDED DECEMBER 31,
                                                              -------------------------------
                                                               1999        1998        1997
- ---------------------------------------------------------------------------------------------
<S>                                                           <C>         <C>         <C>
REVENUE
  Premiums and deposits.....................................  $ 8,344     $ 8,021     $ 7,294
  Net investment income.....................................    4,766       4,536       4,171
  Other income..............................................      970         922         861
                                                              -------     -------     -------
      TOTAL REVENUE.........................................   14,080      13,479      12,326
                                                              -------     -------     -------
BENEFITS AND EXPENSES
  Benefit payments to policyowners and beneficiaries........    4,023       3,602       3,329
  Net additions to policy benefit reserves..................    4,469       4,521       4,026
  Net transfers to separate accounts........................      516         564         566
                                                              -------     -------     -------
      TOTAL BENEFITS........................................    9,008       8,687       7,921
  Operating expenses........................................    1,287       1,297       1,138
                                                              -------     -------     -------
      TOTAL BENEFITS AND EXPENSES...........................   10,295       9,984       9,059
                                                              -------     -------     -------
      GAIN FROM OPERATIONS BEFORE DIVIDENDS AND TAXES.......    3,785       3,495       3,267
Policyowner dividends.......................................    3,091       2,869       2,636
                                                              -------     -------     -------
      GAIN FROM OPERATIONS BEFORE TAXES.....................      694         626         631
Income tax expense..........................................      203         301         356
                                                              -------     -------     -------
      NET GAIN FROM OPERATIONS..............................      491         325         275
Net realized capital gains..................................      846         484         414
                                                              -------     -------     -------
      NET INCOME............................................  $ 1,337     $   809     $   689
                                                              =======     =======     =======
</TABLE>

   The Accompanying Notes are an Integral Part of these Financial Statements

                                     B- 19  Consolidated Statement of Operations
<PAGE>   52

THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
Consolidated Statement of Changes in Surplus
(in millions)

<TABLE>
<CAPTION>
                                                                       FOR THE YEAR ENDED
                                                                          DECEMBER 31,
                                                                --------------------------------
                                                                 1999         1998         1997
- ------------------------------------------------------------------------------------------------
<S>                                                             <C>          <C>          <C>
BEGINNING OF YEAR...........................................    $4,741       $4,101       $3,515
  Net income................................................     1,337          809          689
  Increase (decrease) in net unrealized gains...............       213         (147)         576
  Increase in investment reserves...........................      (377)         (20)        (526)
  Charge-off of goodwill (Note 7)...........................      (842)          --           --
  Other, net................................................        (3)          (2)        (153)
                                                                ------       ------       ------
  NET INCREASE IN SURPLUS...................................       328          640          586
                                                                ------       ------       ------
END OF YEAR BALANCE.........................................    $5,069       $4,741       $4,101
                                                                ======       ======       ======
</TABLE>

   The Accompanying Notes are an Integral Part of these Financial Statements

Consolidated Statement of Changes in Surplus
                                     B- 20
<PAGE>   53

THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
Consolidated Statement of Cash Flows
(in millions)

<TABLE>
<CAPTION>
                                                                  FOR THE YEAR ENDED DECEMBER 31,
                                                                -----------------------------------
                                                                 1999          1998          1997
- ---------------------------------------------------------------------------------------------------
<S>                                                             <C>           <C>           <C>
CASH FLOWS FROM OPERATING ACTIVITIES
  Insurance and annuity premiums............................    $ 9,260       $ 8,876       $ 8,093
  Investment income received................................      4,476         4,216         3,928
  Disbursement of policy loans, net of repayments...........       (358)         (416)         (360)
  Benefits paid to policyowners and beneficiaries...........     (4,012)       (3,572)       (3,316)
  Net transfers to separate accounts........................       (516)         (564)         (565)
  Policyowner dividends paid................................     (2,862)       (2,639)       (2,347)
  Operating expenses and taxes..............................     (1,699)       (1,749)       (1,722)
  Other, net................................................        (56)          (83)          124
                                                                -------       -------       -------
       NET CASH PROVIDED BY OPERATING ACTIVITIES............      4,233         4,069         3,835
                                                                -------       -------       -------
CASH FLOWS FROM INVESTING ACTIVITIES
  PROCEEDS FROM INVESTMENTS SOLD OR MATURED
     Bonds..................................................     20,788        28,720        38,284
     Common and preferred stocks............................     13,331        10,359         9,057
     Mortgage loans.........................................      1,356         1,737         1,012
     Real estate............................................        216           159           302
     Other investments......................................        830           768           398
                                                                -------       -------       -------
                                                                 36,521        41,743        49,053
                                                                -------       -------       -------
  COST OF INVESTMENTS ACQUIRED
     Bonds..................................................     22,849        30,873        41,169
     Common and preferred stocks............................     13,794         9,642         9,848
     Mortgage loans.........................................      2,500         3,135         2,309
     Real estate............................................        362           268           202
     Other investments......................................      1,864           567           359
                                                                -------       -------       -------
                                                                 41,369        44,485        53,887
                                                                -------       -------       -------
  Net increase (decrease) in securities lending and other...        499          (624)          440
                                                                -------       -------       -------
       NET CASH USED IN INVESTING ACTIVITIES................     (4,349)       (3,366)       (4,394)
                                                                -------       -------       -------
       NET (DECREASE) INCREASE IN CASH AND TEMPORARY
        INVESTMENTS.........................................       (116)          703          (559)
Cash and temporary investments, beginning of year...........      1,275           572         1,131
                                                                -------       -------       -------
Cash and temporary investments, end of year.................    $ 1,159       $ 1,275       $   572
                                                                =======       =======       =======
</TABLE>

   The Accompanying Notes are an Integral Part of these Financial Statements

                                     B- 21  Consolidated Statement of Cash Flows
<PAGE>   54

THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
Notes to Consolidated Statutory Financial Statements
December 31, 1999, 1998 and 1997

NOTE 1 -- BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

The accompanying consolidated statutory financial statements include the
accounts of The Northwestern Mutual Life Insurance Company ("Company") and its
wholly-owned subsidiary, Northwestern Long Term Care Insurance Company
("Subsidiary"). The Company and its Subsidiary offer life, annuity, disability
income and long-term care products to the personal, business, estate and
tax-qualified markets.

The consolidated financial statements have been prepared using accounting
policies prescribed or permitted by the Office of the Commissioner of Insurance
of the State of Wisconsin ("statutory basis of accounting").

In 1998, the National Association of Insurance Commissioners ("NAIC") adopted
the Codification of Statutory Accounting Principles ("Codification") guidance,
which will replace the current Accounting Practices and Procedures manual as the
NAIC's primary guidance on statutory accounting. The NAIC is now considering
amendments to Codification that would also be effective upon implementation.
Codification provides guidance for areas where statutory accounting has been
silent and changes current statutory accounting in some areas (e.g., deferred
income taxes are recorded). The Office of the Commissioner of Insurance of the
State of Wisconsin ("OCI") intends to adopt Codification effective January 1,
2001. The Company has not determined the potential effect of Codification, and
the eventual effect of adoption could differ if changes are made prior to the
effective date of January 1, 2001.

Financial statements prepared on the statutory basis of accounting vary from
financial statements prepared on the basis of generally accepted accounting
principles ("GAAP") primarily because on a GAAP basis: (1) policy acquisition
costs are deferred and amortized, (2) investment valuations and insurance
reserves are based on different assumptions, (3) funds received under
deposit-type contracts are not reported as premium revenue, and (4) deferred
taxes are provided for temporary differences between book and tax basis of
certain assets and liabilities. The effects on the financial statements of the
differences between the statutory basis of accounting and GAAP are material to
the Company.

The preparation of financial statements in conformity with the statutory basis
of accounting requires management to make estimates and assumptions that affect
the reported amounts of assets and liabilities at the date of the financial
statements and the reported amounts of revenues and expenses during the
reporting period. Actual future results could differ from these estimates.

INVESTMENTS

The Company's investments are valued on the following bases:

Bonds -- Amortized cost using the interest method; loan-backed and structured
securities are amortized using estimated prepayment rates and, generally, the
prospective adjustment method

Common and preferred stocks -- Common stocks are carried at fair value,
preferred stocks are generally carried at cost, and unconsolidated subsidiaries
are recorded using the equity method

Mortgage loans -- Amortized cost

Real estate -- Lower of cost, less depreciation and encumbrances, or estimated
net realizable value

Policy loans -- Unpaid principal balance, which approximates fair value

Other investments -- Consists primarily of joint venture investments which are
valued at equity in ventures' net assets

Cash and temporary investments -- Amortized cost, which approximates fair value

TEMPORARY INVESTMENTS

Temporary investments consist of debt securities that have maturities of one
year or less at acquisition.

NET INVESTMENT INCOME AND CAPITAL GAINS

Net investment income includes interest and dividends received or due and
accrued on investments, equity in unconsolidated subsidiaries' earnings and the
Company's share of joint venture income. Net investment income is reduced by
investment management expenses, real estate depreciation, depletion related to
energy assets and costs associated with securities lending.

Realized investment gains and losses are reported in income based upon specific
identification of securities sold. Unrealized investment gains and losses
include changes in the fair

Notes to Consolidated Statutory Financial Statements
                                     B- 22
<PAGE>   55

value of common stocks and changes in valuation allowances made for bonds,
preferred stocks, mortgage loans and other investments considered by management
to be impaired.

INTEREST MAINTENANCE RESERVE

The Company is required to maintain an interest maintenance reserve ("IMR"). The
IMR is used to defer realized gains and losses, net of tax, on fixed income
investments resulting from changes in interest rates. Net realized gains and
losses deferred to the IMR are amortized into investment income over the
approximate remaining term to maturity of the investment sold.

INVESTMENT RESERVES

The Company is required to maintain an asset valuation reserve ("AVR"). The AVR
establishes a general reserve for invested asset valuation using a formula
prescribed by state regulations. The AVR is designed to stabilize surplus
against potential declines in the value of investments. In addition, the Company
maintained a $200 million voluntary investment reserve at each of December 31,
1999 and 1998 to absorb potential investment losses exceeding those considered
by the AVR formula. Increases or decreases in these investment reserves are
recorded directly to surplus.

SEPARATE ACCOUNTS

Separate account assets and related policy liabilities represent the segregation
of funds deposited by "variable" life insurance and annuity policyowners.
Policyowners bear the investment performance risk associated with variable
products. Separate account assets are invested at the direction of the
policyowner in a variety of Company-managed mutual funds. Variable product
policyowners also have the option to invest in a fixed interest rate annuity in
the general account of the Company. Separate account assets are reported at fair
value.

PREMIUM REVENUE AND OPERATING EXPENSES

Life insurance premiums are recognized as revenue at the beginning of each
policy year. Annuity and disability income premiums are recognized when received
by the Company. Operating expenses, including costs of acquiring new policies,
are charged to operations as incurred.

OTHER INCOME

Other income includes considerations on supplementary contracts, ceded
reinsurance expense allowances and miscellaneous policy charges.

BENEFIT PAYMENTS TO POLICYOWNERS AND BENEFICIARIES

Benefit payments to policyowners and beneficiaries include death, surrender and
disability benefits, matured endowments and supplementary contract payments.

RESERVES FOR POLICY BENEFITS

Reserves for policy benefits are determined using actuarial estimates based on
mortality and morbidity experience tables and valuation interest rates
prescribed by the OCI. (See Note 3.)

POLICYOWNER DIVIDENDS

Almost all life insurance policies, and certain annuity and disability income
policies issued by the Company are participating. Annually, the Company's Board
of Trustees approves dividends payable on participating policies in the
following fiscal year, which are accrued and charged to operations when
approved.

RECLASSIFICATION

Certain financial statement balances for 1998 and 1997 have been reclassified to
conform to the current year presentation.

                            Notes to Consolidated Statutory Financial Statements
                                     B- 23
<PAGE>   56

NOTE 2 -- INVESTMENTS

DEBT SECURITIES

Debt securities consist of all bonds and fixed-maturity preferred stocks. The
estimated fair values of debt securities are based upon quoted market prices, if
available. For securities not actively traded, fair values are estimated using
independent pricing services or internally developed pricing models.
Statement value, which principally represents amortized cost, and estimated fair
value of the Company's debt securities at December 31, 1999 and 1998 were as
follows:


<TABLE>
<CAPTION>
                           RECONCILIATION TO ESTIMATED FAIR VALUE
                       -----------------------------------------------
                                     GROSS        GROSS      ESTIMATED
                       STATEMENT   UNREALIZED   UNREALIZED     FAIR
  DECEMBER 31, 1999      VALUE       GAINS        LOSSES       VALUE
  -----------------    ---------   ----------   ----------   ---------
                                        (IN MILLIONS)
<S>                    <C>         <C>          <C>          <C>
U.S. Government and
  political
  obligations........   $ 3,855      $   72      $  (167)     $ 3,760
Mortgage-backed
  securities.........     7,736          65         (256)       7,545
Corporate and other
  debt securities....    25,201         249       (1,088)      24,362
                        -------      ------      -------      -------
                         36,792         386       (1,511)      35,667
Preferred stocks.....        85           2           --           87
                        -------      ------      -------      -------
     Total...........   $36,877      $  388      $(1,511)     $35,754
                        =======      ======      =======      =======
</TABLE>


<TABLE>
<CAPTION>
                           RECONCILIATION TO ESTIMATED FAIR VALUE
                       -----------------------------------------------
                                     GROSS        GROSS      ESTIMATED
                       STATEMENT   UNREALIZED   UNREALIZED     FAIR
  DECEMBER 31, 1998      VALUE       GAINS        LOSSES       VALUE
  -----------------    ---------   ----------   ----------   ---------
                                        (IN MILLIONS)
<S>                    <C>         <C>          <C>          <C>
U.S. Government and
  political
  obligations........   $ 3,904      $  461      $   (11)     $ 4,354
Mortgage-backed
  securities.........     7,357         280          (15)       7,622
Corporate and other
  debt securities....    23,627       1,240         (382)      24,485
                        -------      ------      -------      -------
                         34,888       1,981         (408)      36,461
Preferred stocks.....       189           4           (1)         192
                        -------      ------      -------      -------
     Total...........   $35,077      $1,985      $  (409)     $36,653
                        =======      ======      =======      =======
</TABLE>

The statement value and estimated fair value of debt securities by contractual
maturity at December 31, 1999 is shown below. Expected maturities may differ
from contractual maturities because borrowers may have the right to call or
prepay obligations with or without call or prepayment penalties.

<TABLE>
<CAPTION>
                                   STATEMENT    ESTIMATED
                                     VALUE      FAIR VALUE
                                   ---------    ----------
                                        (IN MILLIONS)
<S>                                <C>          <C>
Due in one year or less..........   $   931      $   942
Due after one year through five
  years..........................     5,420        5,412
Due after five years through ten
  years..........................    11,168       10,796
Due after ten years..............    11,622       11,059
                                    -------      -------
                                     29,141       28,209
Mortgage-backed securities.......     7,736        7,545
                                    -------      -------
                                    $36,877      $35,754
                                    =======      =======
</TABLE>

STOCKS

The estimated fair values of common and perpetual preferred stocks are based
upon quoted market prices, if available. For securities not actively traded,
fair values are estimated using independent pricing services or internally
developed pricing models.

The adjusted cost of common and preferred stock held by the Company at December
31, 1999 and 1998 was $4.9 billion and $4.3 billion, respectively.

MORTGAGE LOANS AND REAL ESTATE

Mortgage loans are collateralized by properties located throughout the United
States and Canada. The Company attempts to minimize mortgage loan investment
risk by diversification of geographic locations and types of collateral
properties.

The fair value of mortgage loans as of December 31, 1999 and 1998 was $13.2
billion and $12.9 billion, respectively. The fair value of the mortgage loan
portfolio is estimated by discounting the future estimated cash flows using
current interest rates of debt securities with similar credit risk and
maturities, or utilizing net realizable values.

At December 31, 1999 and 1998, real estate includes $39 million and $61 million,
respectively, acquired through foreclosure and $114 million and $120 million,
respectively, of home office real estate.

Notes to Consolidated Statutory Financial Statements
                                     B- 24
<PAGE>   57

REALIZED AND UNREALIZED GAINS AND LOSSES

Realized investment gains and losses for the years ended December 31, 1999, 1998
and 1997 were as follows:


<TABLE>
<CAPTION>
                                     FOR THE YEAR ENDED
                                     DECEMBER 31, 1999
                              --------------------------------
                                                        NET
                                                      REALIZED
                              REALIZED    REALIZED     GAINS
                               GAINS       LOSSES     (LOSSES)
                              --------    --------    --------
                                       (IN MILLIONS)
<S>                           <C>         <C>         <C>
Bonds.....................     $  219      $(404)      $ (185)
Common and preferred
  stocks..................      1,270       (255)       1,015
Mortgage loans............         22        (12)          10
Real estate...............         92         --           92
Other invested assets.....        308       (189)         119
                               ------      -----       ------
                               $1,911      $(860)       1,051
                               ======      =====       ------
Less: Capital gains
  taxes...................                                244
Less: IMR (losses)
  gains...................                                (39)
                                                       ------
Net realized capital
  gains...................                             $  846
                                                       ======
</TABLE>



<TABLE>
<CAPTION>
                                     FOR THE YEAR ENDED
                                     DECEMBER 31, 1998
                              --------------------------------
                                                        NET
                                                      REALIZED
                              REALIZED    REALIZED     GAINS
                               GAINS       LOSSES     (LOSSES)
                              --------    --------    --------
                                       (IN MILLIONS)
<S>                           <C>         <C>         <C>
Bonds.....................     $  514      $(231)      $  283
Common and preferred
  stocks..................        885       (240)         645
Mortgage loans............         18        (11)           7
Real estate...............         41         --           41
Other invested assets.....        330       (267)          63
                               ------      -----       ------
                               $1,788      $(749)       1,039
                               ======      =====       ------
Less: Capital gains
  taxes...................                                358
Less: IMR (losses)
  gains...................                                197
                                                       ------
Net realized capital
  gains...................                             $  484
                                                       ======
</TABLE>



<TABLE>
<CAPTION>
                                     FOR THE YEAR ENDED
                                     DECEMBER 31, 1997
                              --------------------------------
                                                        NET
                                                      REALIZED
                              REALIZED    REALIZED     GAINS
                               GAINS       LOSSES     (LOSSES)
                              --------    --------    --------
                                       (IN MILLIONS)
<S>                           <C>         <C>         <C>
Bonds.....................     $  518      $(269)       $249
Common and preferred
  stocks..................        533       (150)        383
Mortgage loans............         14        (14)         --
Real estate...............        100         (2)         98
Other invested assets.....        338       (105)        233
                               ------      -----        ----
                               $1,503      $(540)        963
                               ======      =====        ----
Less: Capital gains
  taxes...................                               340
Less: IMR (losses)
  gains...................                               209
                                                        ----
Net realized capital
  gains...................                              $414
                                                        ====
</TABLE>


Changes in unrealized net investment gains and losses for the years ended
December 31, 1999, 1998 and 1997 were as follows:

<TABLE>
<CAPTION>
                                    FOR THE YEAR ENDED
                                       DECEMBER 31,
                                  ----------------------
                                  1999     1998     1997
                                  ----     ----     ----
                                      (IN MILLIONS)
<S>                               <C>      <C>      <C>
Bonds.........................    $(178)   $ (97)   $ 43
Common and preferred stocks...      415       29     528
Mortgage loans................      (10)     (16)     (7)
Real estate...................       (2)      --      --
Other.........................      (12)     (63)     12
                                  -----    -----    ----
                                  $ 213    $(147)   $576
                                  =====    =====    ====
</TABLE>

SECURITIES LENDING

The Company has entered into securities lending agreements whereby certain
securities are loaned to third parties, primarily major brokerage firms. The
Company's policy requires a minimum of 102% of the fair value of the loaned
securities as collateral, calculated on a daily basis in the form of either cash
or securities. Collateral assets received and related liability due to
counterparties of $2.1 billion and $1.5 billion, respectively, are included in
the consolidated statements of financial position at December 31, 1999 and 1998,
and approximate the statement value of securities loaned at those dates.

INVESTMENT IN MGIC

The Company owns 11.3% (11.9 million shares) of the outstanding common stock of
MGIC Investment Corporation ("MGIC"). This investment is accounted for using the
equity method. At December 31, 1999 and 1998, the fair value of the Company's
investment in MGIC exceeded the statement value of $201 million and $180
million, respectively, by $518 million and $296 million, respectively.

In August 1998, the Company delivered 8.9 million shares of MGIC to a brokerage
firm to settle a forward contract. In conjunction with the settlement, the
Company recorded a $114 million realized gain.

DERIVATIVE FINANCIAL INSTRUMENTS

In the normal course of business, the Company enters into transactions to reduce
its exposure to fluctuations in interest rates, foreign currency exchange rates
and market volatility. These hedging strategies include the use of forwards,
futures, options and swaps.

The Company held the following positions for hedging purposes at December 31,
1999 and 1998:

                            Notes to Consolidated Statutory Financial Statements
                                     B- 25
<PAGE>   58

<TABLE>
<CAPTION>
                                                NOTIONAL AMOUNTS
                                           ---------------------------
                                           DECEMBER 31,   DECEMBER 31,
     DERIVATIVE FINANCIAL INSTRUMENT           1999           1998                     RISKS REDUCED
     -------------------------------       ------------   ------------                 -------------
                                                  (IN MILLIONS)
<S>                                        <C>            <C>            <C>
Foreign Currency
  Forward Contracts......................      $967           $601       Currency exposure on foreign-denominated
                                                                         investments
Common Stock Futures.....................       620            657       Stock market price fluctuation.
Bond Futures.............................        50            379       Bond market price fluctuation.
Options to acquire Interest Rate Swaps...       419            419       Interest rates payable on certain annuity
                                                                         and insurance contracts.
Foreign Currency and
  Interest Rate Swaps....................       203             94       Interest rates on variable rate notes and
                                                                         currency exposure on foreign-denominated
                                                                         bonds.
Default Swaps............................        52             --       Default exposure on certain bond
                                                                         investments.
</TABLE>

The notional or contractual amounts of derivative financial instruments are used
to denominate these types of transactions and do not represent the amounts
exchanged between the parties.

In addition to the use of derivatives for hedging purposes, equity swaps were
held for investment purposes during 1999 and 1998. The notional amount of equity
swaps outstanding at December 31, 1999 and 1998 was $136 million and $138
million, respectively.

Foreign currency forwards, foreign currency swaps, stock futures and equity
swaps are reported at fair value. Resulting gains and losses on these contracts
are unrealized until expiration of the contract. There is no statement value
reported for interest rate swaps, bond futures and options to acquire interest
rate swaps prior to the settlement of the contract, at which time realized gains
and losses are deferred to IMR. Changes in the value of derivative instruments
are expected to offset gains and losses on the hedged investments. During 1999
and 1998, net realized and unrealized gains on investments were partially offset
by net realized losses of $55 million and $104 million, respectively, and net
unrealized gains (losses) of $17 million and $(58) million, respectively, on
derivative instruments. The effect of derivative instruments in 1997 was not
material to the Company's results of operations.

NOTE 3 -- RESERVES FOR POLICY BENEFITS

Life insurance reserves on substantially all policies issued since 1978 are
based on the Commissioner's Reserve Valuation Method with interest rates ranging
from 3 1/2% to 5 1/2%. Other life policy reserves are primarily based on the net
level premium method employing various mortality tables at interest rates
ranging from 2% to 4 1/2%.

Deferred annuity reserves on contracts issued since 1985 are valued primarily
using the Commissioner's Annuity Reserve Valuation Method with interest rates
ranging from 3 1/2% to 6 1/4%. Other deferred annuity reserves are based on
contract value. Immediate annuity reserves are based on present values of
expected benefit payments at interest rates ranging from 3 1/2% to 7 1/2%.

Active life reserves for disability income ("DI") policies issued since 1987 are
primarily based on the two-year preliminary term method using a 4% interest rate
and the 1985 Commissioner's Individual Disability Table A ("CIDA") for
morbidity. Active life reserves for prior DI policies are based on the net level
premium method, a 3% to 4% interest rate and the 1964 Commissioner's Disability
Table for morbidity. Disabled life reserves for DI policies are based on the
present values of expected benefit payments primarily using the 1985 CIDA
(modified for Company experience in the first four years of disability) with
interest rates ranging from 3% to 5 1/2%.

Use of these actuarial tables and methods involves estimation of future
mortality and morbidity. Actual future experience could differ from these
estimates.

NOTE 4 -- EMPLOYEE AND AGENT BENEFIT PLANS

The Company sponsors noncontributory defined benefit retirement plans for all
eligible employees and agents. The expense associated with these plans is
generally recorded by the Company in the period contributions are funded. As of
January 1, 1999, the most recent actuarial valuation date available, the
qualified defined benefit plans were fully funded. The Company recorded a
liability of $109 million and $98 million for nonqualified defined benefit plans
at
Notes to Consolidated Statutory Financial Statements
                                     B- 26
<PAGE>   59

December 31, 1999 and 1998, respectively. In addition, the Company has a
contributory 401(k) plan for eligible employees and a noncontributory defined
contribution plan for all full-time agents. The Company's contributions are
expensed in the period contributions are made to the plans. The Company recorded
$31 million, $29 million and $27 million of total expense related to its defined
benefit and defined contribution plans for the years ended December 31, 1999,
1998 and 1997, respectively. The defined benefit and defined contribution plans'
assets of $2.2 billion and $1.9 billion at December 31, 1999 and 1998,
respectively, were primarily invested in the separate accounts of the Company.

In addition to pension and retirement benefits, the Company provides certain
health care and life insurance benefits ("postretirement benefits") for retired
employees. Substantially all employees may become eligible for these benefits if
they reach retirement age while working for the Company. Postretirement benefit
costs for the years ended December 31, 1999, 1998 and 1997 were a net expense
(benefit) of $5.0 million, $1.8 million and ($1.3) million, respectively.

<TABLE>
<CAPTION>
                            DECEMBER 31,         DECEMBER 31,
                                1999                 1998
                         ------------------   ------------------
<S>                      <C>                  <C>
Unfunded postretirement
  benefit obligation
  for retirees and
  other fully eligible
  employees (Accrued in
  statement of
  financial
  position)............  $40 million          $35 million
Estimated
  postretirement
  benefit obligation
  for active non-vested
  employees (Not
  accrued until
  employee vests)......  $68 million          $56 million
Discount rate..........  7%                   7%
Health care cost trend
  rate.................  10% to an ultimate   10% to an ultimate
                         5%, declining 1%     5%, declining 1%
                         for 5 years          for 5 years
</TABLE>

If the health care cost trend rate assumptions were increased by 1%, the accrued
postretirement benefit obligation as of December 31, 1999 and 1998 would have
been increased by $6 million and $5 million, respectively.

At December 31, 1999 and 1998, the recorded postretirement benefit obligation
was reduced by $28 million and $23 million, respectively, for health care
benefit plan assets. These assets were primarily invested in the separate
accounts of the Company.

NOTE 5 -- REINSURANCE

In the normal course of business, the Company seeks to limit its exposure to
loss on any single insured and to recover a portion of benefits paid by ceding
to reinsurers under excess coverage and coinsurance contracts. The Company
retains a maximum of $25 million of coverage per individual life and $35 million
maximum of coverage per joint life. The Company has an excess reinsurance
contract for disability income policies with retention limits varying based upon
coverage type.

The amounts shown in the accompanying consolidated financial statements are net
of reinsurance. Reserves for policy benefits at December 31, 1999 and 1998 were
reported net of ceded reserves of $584 million and $518 million, respectively.
The effect of reinsurance on premiums and benefits for the years ended December
31, 1999, 1998 and 1997 was as follows:

<TABLE>
<CAPTION>
                                1999     1998     1997
                               ------   ------   ------
                                    (IN MILLIONS)
<S>                            <C>      <C>      <C>
Direct premiums and
  deposits...................  $8,785   $8,426   $7,647
Premiums ceded...............    (441)    (405)    (353)
                               ------   ------   ------
Net premium and deposits.....  $8,344   $8,021   $7,294
                               ======   ======   ======
Benefits to policyowners and
  beneficiaries..............   9,205   $8,869   $8,057
Benefits ceded...............    (197)    (182)    (136)
                               ------   ------   ------
Net benefits to policyowners
  and beneficiaries..........  $9,008   $8,687   $7,921
                               ======   ======   ======
</TABLE>

In addition, the Company received $133 million, $121 million and $115 million
for the years ended December 31, 1999, 1998 and 1997, respectively, from
reinsurers representing allowances for reimbursement of commissions and other
expenses. These amounts are included in other income in the consolidated
statement of operations.

Reinsurance contracts do not relieve the Company from its obligations to
policyowners. Failure of reinsurers to honor their obligations could result in
losses to the Company; consequently, allowances are established for amounts
deemed uncollectible. The Company evaluates the financial condition of its
reinsurers and monitors concentrations of credit risk arising from similar
geographic regions, activities or economic characteristics of the reinsurers to
minimize its exposure to significant losses from reinsurer insolvencies.

                            Notes to Consolidated Statutory Financial Statements
                                     B- 27
<PAGE>   60

NOTE 6 -- INCOME TAXES

Provisions for income taxes are based on current income tax payable without
recognition of deferred taxes. The Company files a consolidated life-nonlife
federal income tax return. Federal income tax returns for years through 1995 are
closed as to further assessment of tax. Adequate provision has been made in the
financial statements for any additional taxes, which may become due with respect
to the open years.

The Company's taxable income can vary significantly from gain from operations
before taxes due to differences between book and tax valuation of assets and
liabilities (e.g., investments and policy benefit reserves). The Company pays a
tax that is assessed only on the surplus of mutual life insurance companies
("equity tax"), and also, the Company must capitalize and amortize, as opposed
to immediately deducting, an amount deemed to represent the cost of acquiring
new business ("DAC tax").

The Company's effective tax rate on gains from operations before taxes for the
years ended December 31, 1999, 1998 and 1997 was 29%, 48%, and 56% respectively.
In 1999, the effective rate was less than the federal corporate rate of 35% due
primarily to differences between book and tax investment income. In 1998 and
1997, the effective rate was greater than 35% due primarily to the equity tax
and DAC tax.

NOTE 7 -- RELATED PARTY TRANSACTIONS

The Company acquired Frank Russell Company ("Frank Russell") effective January
1, 1999 for a purchase price of approximately $950 million. Frank Russell is a
leading investment management and consulting firm, providing investment advice,
analytical tools and investment vehicles to institutional and individual
investors in more than 30 countries. This investment is accounted for using the
equity method and is included in common stocks in the consolidated statement of
financial position. In 1999, the Company charged-off directly from surplus
approximately $842 million, representing the total goodwill associated with the
acquisition. The Company has received permission from the OCI for this
charge-off. The Company has unconditionally guaranteed certain debt obligations
of Frank Russell, including $350 million of senior notes and up to $150 million
of other credit facilities.

During 1999, the Company transferred appreciated equity investments to a
wholly-owned subsidiary as a capital contribution to the subsidiary. A realized
capital gain of $287 million was recorded on this transaction based on the fair
value of the assets upon transfer.

NOTE 8 -- CONTINGENCIES

The Company has guaranteed certain obligations of its other affiliates. These
guarantees totaled approximately $101 million at December 31, 1999 and are
generally supported by the underlying net asset values of the affiliates.

In addition, the Company routinely makes commitments to fund mortgage loans or
other investments in the normal course of business. These commitments aggregated
to $1.9 billion at December 31, 1999 and were extended at market interest rates
and terms.

The Company is engaged in various legal actions in the normal course of its
investment and insurance operations. In the opinion of management, any losses
resulting from such actions would not have a material effect on the Company's
financial position.

Notes to Consolidated Statutory Financial Statements
                                     B- 28
<PAGE>   61

[PRICEWATERHOUSECOOPERS LLP - LETTERHEAD]

REPORT OF INDEPENDENT ACCOUNTANTS

To the Board of Trustees and Policyowners of
The Northwestern Mutual Life Insurance Company

We have audited the accompanying consolidated statement of financial position of
The Northwestern Mutual Life Insurance Company and its subsidiary as of December
31, 1999 and 1998, and the related consolidated statements of operations, of
changes in surplus and of cash flows for each of the three years in the period
ended December 31, 1999. These consolidated financial statements are the
responsibility of the Company's management. Our responsibility is to express an
opinion on these consolidated financial statements based on our audits.

We conducted our audits in accordance with auditing standards generally accepted
in the United States. 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.

As described in Note 1 to the financial statements, the Company prepared these
consolidated financial statements using accounting practices prescribed or
permitted by the Office of the Commissioner of Insurance of the State of
Wisconsin (statutory basis of accounting), which practices differ from
accounting principles generally accepted in the United States. Accordingly, the
consolidated financial statements are not intended to represent a presentation
in accordance with generally accepted accounting principles. The effects on the
consolidated financial statements of the variances between the statutory basis
of accounting and generally accepted accounting principles, although not
reasonably determinable, are presumed to be material.

In our opinion, the consolidated financial statements audited by us (1) do not
present fairly in conformity with generally accepted accounting principles, the
financial position of The Northwestern Mutual Life Insurance Company and its
subsidiary as of December 31, 1999 and 1998, or the results of their operations
or their cash flows for each of the three years in the period ended December 31,
1999 because of the effects of the variances between the statutory basis of
accounting and generally accepted accounting principles referred to in the
preceding paragraph and (2) do present fairly, in all material respects, the
financial position of The Northwestern Mutual Life Insurance Company and its
subsidiary as of December 31, 1999 and 1998 and the results of their operations
and their cash flows for each of the three years in the period ended December
31, 1999, on the basis of accounting described in Note 1.

/s/ PriceWaterhousecoopers LLP

January 24, 2000



Accountants' Report                  B- 29

<PAGE>   62

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                           PAGE
                                                                           ----
<S>                                                                        <C>
DISTRIBUTION OF THE CONTRACTS...............................................B-2

DETERMINATION OF ANNUITY PAYMENTS...........................................B-2
         Amount of Annuity Payments.........................................B-2
         Annuity Unit Value.................................................B-3
         Illustrations of Variable Annuity Payments.........................B-3

VALUATION OF ASSETS OF THE ACCOUNT..........................................B-4

TRANSFERABILITY RESTRICTIONS................................................B-4

EXPERTS.....................................................................B-4

FINANCIAL STATEMENTS OF THE ACCOUNT.........................................B-5
(for the two years ended December 31, 1999)

REPORT OF INDEPENDENT ACCOUNTANTS..........................................B-17
(for the two years ended December 31, 1999)

FINANCIAL STATEMENTS OF NORTHWESTERN MUTUAL................................B-18
(for the three years ended December 31, 1999)

REPORT OF INDEPENDENT ACCOUNTANTS..........................................B-29
(for the three years ended December 31, 1999)
</TABLE>


                                      B-30

<PAGE>   63



                                     PART C
                                OTHER INFORMATION

Item 24.          Financial Statements and Exhibits
         (a)             Financial Statements
                         The financial statements of NML Variable Annuity
                         Account A and The Northwestern Mutual Life Insurance
                         Company are included in the Statement of Additional
                         Information.

                         NML Variable Annuity Account A
                         (for the two years ended December 31, 1999)
                           Statement of Assets and Liabilities
                           Statement of Operations
                           Changes in Equity
                           Notes to Financial Statements
                           Report of Independent Accountants

                         The Northwestern Mutual Life Insurance Company
                         (for the three years ended December 31, 1999)
                           Consolidated Statement of Financial Position
                           Consolidated Statement of Operations
                           Consolidated Statement of Changes in Surplus
                           Consolidated Statement of Cash Flows
                           Notes to Consolidated Statutory Financial Statements
                           Report of Independent Accountants

         (b)      Exhibits

         Exhibit B(10)              Consent of PricewaterhouseCoopers LLP

         The following exhibits were filed in electronic format with the
         Registration Statement on Form N-4 for NML Variable Annuity Account A,
         File No. 333-72913, CIK 0000790162, dated January 27, 2000, and are
         incorporated herein by reference:

         Exhibit B(4)(a)              Flexible Payment Variable Annuity
                                      Front Load Contract, RR.V.A. (032000) (sex
                                      neutral)

         Exhibit B(4)(a)(1)           Flexible Payment Variable Annuity Back
                                      Load Contract, RR.V.A. (032000) (sex
                                      neutral)

         Exhibit B(4)(b)              Variable Annuity Front Load and
                                      Back Load Contract Payment Rate Tables,
                                      RR.V.A.B (032000), included in Exhibits
                                      B(4)(a) and B(4)(a)(1) above (sex
                                      distinct)

         Exhibit B(4)(c)              Enhanced Death Benefit for Front
                                      Load and Back Load Contracts, VA. EDB.
                                      (032000), included in Exhibits B(4)(a) and
                                      B(4)(a)(1) above

         Exhibit B(4)(d)              Waiver of Withdrawal Charge for
                                      Back Load Contract, VA.WWC. (032000),
                                      included in Exhibit B(4)(a)(1) above

         Exhibit B(5)                 Application forms for Front Load and
                                      Back Load Contracts, included in Exhibits
                                      B(4)(a) and B(4)(a)(1) above


                                      C-1
<PAGE>   64

         The following exhibits were filed in electronic format with the
         Registration Statement on Form N-4 for NML Variable Annuity Account A,
         File No. 333-72913, CIK 0000790162, dated February 25, 1999, and are
         incorporated herein by reference:

         Exhibit B(8)(a)              Form of Participation Agreement
                                      Among Russell Insurance Funds, Russell
                                      Fund Distributors, Inc. and The
                                      Northwestern Mutual Life Insurance Company

         Exhibit B(8)(b)              Form of Administrative Service Fee
                                      Agreement between The Northwestern Mutual
                                      Life Insurance Company and Frank Russell
                                      Company

         The following exhibit was filed in electronic format with the
         Registration Statement on Form S-6 for Northwestern Mutual Variable
         Life Account, File No. 333-59103, CIK 0000742277, dated July 15, 1998,
         and is incorporated herein by reference.

         Exhibit A(6)(b)              Amended By-Laws of The Northwestern
                                      Mutual Life Insurance Company dated
                                      January 28, 1998

         The following exhibits were filed in electronic format with the
         Registration Statement on Form N-4 for NML Variable Annuity Account A,
         File No. 333-22455, CIK 0000790162, dated February 27, 1997, and are
         incorporated herein by reference:

         Exhibit 99(b)                Resolution of the Board of Trustees
                                      of The Northwestern Mutual Life Insurance
                                      Company creating the Account and
                                      resolution of the Executive Committee
                                      designating the formations of "NML
                                      Variable Annuity Account A" and "NML
                                      Variable Annuity Account B"

         Exhibit A(3)(A)              Distribution Contract

         The following exhibit was filed in electronic format with
         Post-Effective Amendment No. 6 on Form N-4 for NML Variable Annuity
         Account A, File No. 33-58476, CIK 0000790162, dated November 13, 1995,
         and is incorporated herein by reference:

         EX-99.B1                     Restated Articles of Incorporation of The
                                      Northwestern Mutual Life Insurance Company

Item 25.   Directors and Officers of the Depositor

The following lists include all of the Trustees, executive officers and other
officers of The Northwestern Mutual Life Insurance Company as of March 1, 2000,
without regard to their activities relating to variable annuity contracts or
their authority to act or their status as "officers" as that term is used for
certain purposes of the federal securities laws and rules thereunder.

TRUSTEES

<TABLE>
<CAPTION>
Name                                               Business Address
- ----                                               ----------------
<S>                                               <C>
R. Quintus Anderson                                Aarque Capital Corporation
                                                   20 West Fairmount Avenue
                                                   P.O. Box 109
                                                   Lakewood, NY 14750-0109

Edward E. Barr                                     Sun Chemical Corporation
                                                   222 Bridge Plaza South
                                                   Fort Lee, NJ  07024
</TABLE>

                                      C-2
<PAGE>   65

<TABLE>
<S>                                               <C>
Gordon T. Beaham III                               Faultless Starch/Bon Ami Co.
                                                   1025 West Eighth Street
                                                   Kansas City, MO 64101

Robert C. Buchanan                                 Fox Valley Corporation
                                                   100 West Lawrence Street
                                                   P.O. Box 727
                                                   Appleton, WI  54911

George A. Dickerman                                Spalding Sports Worldwide
                                                   425 Meadow Street
                                                   P.O. Box 901
                                                   Chicopee, MA  01021-0901

Pierre S. du Pont                                  Richards, Layton and Finger
                                                   P.O. Box 551
                                                   1 Rodney Square
                                                   Wilmington, DE 19899

James D. Ericson                                   The Northwestern Mutual Life
                                                     Insurance Company
                                                   720 East Wisconsin Avenue
                                                   Milwaukee, WI 53202

J. E. Gallegos                                     Gallegos Law Firm
                                                   460 St. Michaels Drive
                                                   Building 300
                                                   Santa Fe, NM 87505

Stephen N. Graff                                   805 Lone Tree Road
                                                   Elm Grove, WI 53122-2014

Patricia Albjerg Graham                            Graduate School of Education
                                                   Harvard University
                                                   420 Gutman
                                                   Cambridge, MA  02138

Stephen F. Keller                                  101 South Las Palmas Avenue
                                                   Los Angeles, CA 90004

Barbara A. King                                    Landscape Structures, Inc.
                                                   Route 3
                                                   601-7th Street South
                                                   Delano, MN 55328

J. Thomas Lewis                                    228 St. Charles Avenue
                                                   Suite 1024
                                                   New Orleans, LA 70130

Daniel F. McKeithan, Jr.                           Tamarack Petroleum Company, Inc.
                                                   Suite 1920
                                                   777 East Wisconsin Avenue
                                                   Milwaukee, WI 53202
</TABLE>

                                      C-3
<PAGE>   66

<TABLE>
<S>                                               <C>
Guy A. Osborn                                      Universal Foods Corp.
                                                   433 East Michigan Street
                                                   Milwaukee, WI 53202

Timothy D. Proctor                                 Diageo plc
                                                   8 Henrietta Place
                                                   London W1M 9AG
                                                   United Kingdom

H. Mason Sizemore, Jr.                             The Seattle Times
                                                   Fairview Avenue North and John Street
                                                   P.O. Box 70
                                                   Seattle, WA  98109

Harold B. Smith, Jr.                               Illinois Tool Works, Inc.
                                                   3600 West Lake Avenue
                                                   Glenview, IL 60625-5811

Sherwood H. Smith, Jr.                             Carolina Power & Light Company
                                                   411 Fayetteville Street Mall
                                                   P.O. Box 1551
                                                   Raleigh, NC  27602

Peter M. Sommerhauser                              Godfrey & Kahn, S.C.
                                                   780 North Water Street
                                                   Milwaukee, WI 53202-3590

John E. Steuri                                     Advanced Thermal Technologies
                                                   2102 Riverfront Drive, Suite 120
                                                   Little Rock, AR 72202-1747

John J. Stollenwerk                                Allen-Edmonds Shoe Corporation
                                                   201 East Seven Hills Road
                                                   P.O. Box 998
                                                   Port Washington, WI 53074-0998

Barry L. Williams                                  Williams Pacific Ventures, Inc.
                                                   100 First Street
                                                   Suite 2350
                                                   San Francisco, CA 94105

Kathryn D. Wriston                                 c/o Shearman & Sterling
                                                   599 Lexington Avenue
                                                   Room 1126
                                                   New York, NY 10022

Edward J. Zore                                     The Northwestern Mutual Life
                                                     Insurance Company
                                                   720 East Wisconsin Avenue
                                                   Milwaukee, WI 53202
</TABLE>


                                      C-4


<PAGE>   67


EXECUTIVE OFFICERS

<TABLE>
<CAPTION>
Name                                        Title
- ----                                        -----
<S>                                        <C>
Deborah A. Beck                             Senior Vice President
William H. Beckley                          Senior Vice President
Robert J. Berdan                            Vice President
John M. Bremer                              Executive Vice President, General Counsel & Secretary
Peter W. Bruce                              Executive Vice President
Steven T. Catlett                           Vice President
Mark G. Doll                                Senior Vice President
Thomas E. Dyer                              Vice President
James D. Ericson                            President and Chief Executive Officer, Trustee
Richard L. Hall                             Senior Vice President
William C. Koenig, FSA                      Senior Vice President and Chief Actuary
Gary E. Long                                Vice President and Controller
Susan A. Lueger                             Vice President
Meridee J. Maynard                          Vice President
Donald L. Mellish                           Senior Vice President
Bruce L. Miller                             Senior Vice President
Gregory C. Oberland                         Vice President
Barbara F. Piehler                          Vice President
James F. Reiskytl                           Vice President
Mason G. Ross                               Senior Vice President
John E. Schlifske                           Vice President
Leonard F. Stecklein                        Senior Vice President - Policyowner Services
Frederic H. Sweet                           Senior Vice President
J. Edward Tippetts                          Vice President
Martha M. Valerio                           Vice President
W. Ward White                               Vice President
Walt J. Wojcik                              Senior Vice President
Edward J. Zore                              Executive Vice President and Trustee
</TABLE>

OTHER OFFICERS

<TABLE>
<CAPTION>
Name                                                                   Title
- ----                                                                   -----
<S>                                                  <C>
John M. Abbott                                       Associate Director - Benefits Research
Carl G. Amick                                        Director - Disability Benefits
Thomas R. Anderson                                   Vice President - Marketing
Maria J. Avila                                       Assistant Controller
Michael J. Backus                                    Associate Director - Information Systems
John E. Bailey                                       Senior Actuary
Nicholas H. Bandow                                   Assistant Director - Information Systems
Lynn F. Bardele                                      Assistant Director - Field Training & Development
Margaret A. Barkley                                  Assistant Director
Walter L. Barlow                                     Assistant Director - Education
Rebekah B. Barsch                                    Director - NML Foundation
Sandra L. Barton                                     Assistant Director - Marketing
Bradford P. Bauer                                    Assistant Director - Advanced Marketing
Beth M. Berger                                       Assistant General Counsel & Assistant Secretary
Frederick W. Bessette                                Assistant General Counsel & Assistant Secretary
Carrie L. Bleck                                      Assistant Director
</TABLE>


                                      C-5
<PAGE>   68

<TABLE>
<S>                                                 <C>
D. Rodney Bluhm                                      Assistant General Counsel
Jessica J. Borgmann                                  Assistant Director - Agency Recruiting
Willette Bowie                                       Employee Relations Director
Martin R. Braasch                                    Director - Underwriting Standards & Services
Patricia R. Braeger                                  Associate Director - Information Systems
James A. Brewer                                      Investment Research Officer
William J. Buholzer                                  Employee Relations Director
Michael S. Bula                                      Assistant General Counsel
Jerry C. Burg                                        Associate Director - Field Benefits
Pency P. Byhardt                                     Assistant Director - New Business
Gregory B. Bynan                                     Director - Corporate Services
Kim M. Cafaro                                        Assistant General Counsel & Assistant Secretary
John E. Cain                                         Assistant Director - Life Benefits
Gwen C. Canady                                       Assistant Director-Mutual Funds
Shanklin B. Cannon, M.D.                             Medical Director - Life Products/Research
Terese J. Capizzi                                    Assistant Director
Kurt P. Carbon                                       Assistant Regional Director
John P. Carrick                                      Assistant Director - Investment Services
Michael G. Carter                                    Assistant General Counsel & Assistant Secretary
William W. Carter                                    Associate Actuary
John E. Caspari                                      Assistant Director - Advertising & Corporate
                                                       Information
Walter J. Chossek                                    Associate Controller
Thomas R. Christenson                                Director - Advanced Marketing
Eric P. Christophersen                               Associate Director
Alan E. Close                                        Associate Controller
Carolyn M. Colbert                                   Assistant Director - New Business
Margaret Winter Combe                                Director - Corporate Development
Virginia A. Corwin                                   Assistant Director - New Business
Barbara E. Courtney                                  Associate Director - Mutual Funds
Dennis J. Darland                                    Assistant Director - Disability Income
Thomas H. Davis                                      Associate Director - Information Systems
Nicholas De Fino                                     Assistant Director
Carol A. Detlaf                                      Director - Annuity Administration
Colleen Devlin                                       Assistant Director - Communications
Glen W. DeZeeuw                                      Director - Agency Services
Joseph Dobering, III                                 Director - Underwriting Standards & Services
Jennifer L. Docea                                    Actuary
Lisa C. Dodd                                         Actuary
Richard P. Dodd                                      Assistant Director - Agency
Daniel C. Dougherty                                  Director - Personal Markets
Margaret T. Dougherty                                Assistant Director - Information Systems
John R. Dowell                                       Director - Workforce Diversity
William O. Drehfal                                   Assistant Director - Media Services
Steven J. Dryer                                      Associate Director
Jeffrey S. Dunn                                      Vice President
John E. Dunn                                         Assistant General Counsel & Assistant Secretary
Somayajulu Durvasula                                 Associate Director - Field Financial
James R. Eben                                        Assistant General Counsel & Assistant Secretary
Magda El Sayed                                       Assistant Director - Information Systems
Michael S. Ertz                                      Assistant Director - Advanced Marketing
Thomas F. Fadden                                     Assistant Director - Information Systems
Christina H. Fiasca                                  Director - Policyowner Services
Zenia J. Fieldbinder                                 Assistant Director - Annuity Accumulation
</TABLE>


                                      C-6

<PAGE>   69

<TABLE>
<S>                                                <C>
Richard F. Fisher                                    Senior Actuary
Dennis J. Fitzpatrick                                Director - Advanced Marketing
Jon T. Flaschner                                     Director - Policyowner Services
Kate M. Fleming                                      Assistant General Counsel & Assistant Secretary
Carol J. Flemma                                      Assistant Director - Marketing
John E. Fobes II                                     Assistant Director - Agency Services
Donald Forecki                                       Investment Officer
Phillip B. Franczyk                                  Vice President
Stephen H. Frankel                                   Vice President
Anne A. Frigo                                        Assistant Director - New Business
Richard R. Garthwait                                 Vice President - Field Financial
David L. Georgenson                                  Director - Agent Development
Timothy L. Gergens                                   Financial Officer
Paulette A. Getschman                                Assistant Director - Policyowner Services
James W. Gillespie                                   Vice President
Walter M. Givler                                     Director - Corporate Services
Robert P. Glazier                                    Director - New Business
Robert K. Gleeson, M.D.                              Vice President - Medical Director
Mark J. Gmach                                        Director - Agency
Jason G. Goetze                                      Assistant Director - Marketing
David Lee Gosse                                      Assistant Director - Disability Benefits
William F. Grady                                     Director of Field Finances
John M. Grogan                                       Director - Disability Income
Thomas C. Guay                                       Director - Field Financial
Gerald A. Haas                                       Assistant Director - Information Systems
Patricia Ann Hagen                                   Assistant Director - Information Systems
Ronald D. Hagen                                      Vice President
Lori A. Hanes                                        Director - Human Resources
William M. Harris                                    Assistant Regional Director - South
Dennis R. Hart                                       Assistant Director - Agent Development
James C. Hartwig                                     Vice President - Advanced Marketing
Paul F. Heaton                                       Assistant General Counsel & Assistant Secretary
William L. Hegge                                     Associate Director of Telecommunications
Wayne F. Heidenreich                                 Medical Director
Jacquelyn F. Heise                                   Associate Director - Information Systems
Robert L. Hellrood                                   Director - New Business
Herbert F. Hellwig                                   Assistant Director - Personal Markets
Jane A. Herman                                       Director - Term Upgrade
Gary M. Hewitt                                       Vice President & Treasurer
Donna R. Higgins                                     Associate Director - Information Systems
David L. Hilbert                                     Investment Officer
Karla D. Hill                                        Human Resource Officer
Susan G. Hill                                        Assistant Director
John D. Hillmer                                      Assistant Director - Information Systems
Hugh L. Hoffman                                      Assistant Director - Information Systems
Richard S. Hoffmann                                  Director - Audit
Terence J. Holahan                                   Assistant Director - Long Term Care Sales
Bruce Holmes                                         Associate Actuary
Elizabeth S. Idleman                                 Assistant General Counsel & Assistant Secretary
Scott C. Iodice                                      Assistant Director - Agency
Joseph P. Jansky                                     Assistant Director - Corporate Planning
Michael D. Jaquint                                   Assistant Actuary
Dolores A. Juergens                                  Associate Director of Restaurant Operations
Mark Kaprelian                                       Assistant General Counsel & Assistant Secretary
</TABLE>


                                      C-7
<PAGE>   70

<TABLE>
<S>                                                <C>
Marilyn J. Katz                                      Assistant Director - Medical Consultants
John C. Kelly                                        Associate Controller
Kevin C. Kennedy                                     Assistant Director - Architecture
James B. Kern                                        Regional Director - Central Region
Donald C. Kiefer                                     Vice President
Jason T. Klawonn                                     Assistant Actuary
Allen B. Kluz                                        Director - Field Financial
Beatrice C. Kmiec                                    Assistant Regional Director - East
James A. Koelbl                                      Assistant General Counsel & Assistant Secretary
John L. Kordsmeier                                   Director - Policyowner Services
Robert J. Kowalsky                                   Chief Architect
Carol L. Kracht                                      Assistant General Counsel & Assistant Secretary
Martha Krawczak                                      Officer - Life and Disability
Jeffrey J. Krygiel                                   Assistant Actuary
Todd L. Laszewski                                    Associate Actuary
Patrick J. Lavin                                     Director - Disability Benefits
James L. Lavold                                      Associate Director - Meetings
Elizabeth J. Lentini                                 Assistant General Counsel & Assistant Secretary
Sally Jo Lewis                                       Assistant General Counsel & Assistant Secretary
Mark P. Lichtenberger                                Associate Director - LINK Technical Planning
Paul E. Lima                                         Vice President-International Insurance Operations
Steven M. Lindstedt                                  Assistant Director - Information Systems
Melissa C. Lloyd                                     Assistant Director - Advanced Marketing
James Lodermeier                                     Assistant Director - Tax Planning
George R. Loxton                                     Assistant General Counsel & Assistant Secretary
Mary M. Lucci                                        Director - New Business
Christine M. Lucia                                   Human Resources Officer
Mark J. Lucius                                       Corporate Information Officer
Merrill C. Lundberg                                  Assistant General Counsel & Assistant Secretary
Jon K. Magalska                                      Associate Actuary
Jean M. Maier                                        Vice President - Life Benefits
Joseph Maniscalco                                    Associate Director - Information Systems
Raymond J. Manista                                   Assistant General Counsel & Assistant Secretary
Steven C. Mannebach                                  Assistant Director - Field Financial Services
Jeffrey S. Marks                                     Multi Life, Research & Reinsurance Officer
Steve Martinie                                       Assistant General Counsel & Assistant Secretary
Ted A. Matchulat                                     Actuarial Products Officer
Shawn P. Mauser                                      Assistant Director - Personal Markets
Margaret McCabe                                      Director - Policy Benefits Systems
Richard A. McComb                                    Director - Human Resources
William L. McCown                                    Vice President & Investment Counsel
Paul E. McElwee                                      Assistant General Counsel & Assistant Secretary
James L. McFarland                                   Assistant General Counsel & Assistant Secretary
Daniel E. McGinley                                   Director - Management Development
Allan J. McDonell                                    Assistant Director - Equity Compliance
Mark J. McLennon                                     Assistant Director
Arthur J. Mees Jr.                                   Assistant Actuary
Robert J. Meiers                                     Ad Valorem Tax Manager
Larry S. Meihsner                                    Assistant General Counsel & Assistant Secretary
Robert G. Meilander                                  Vice President
Richard E. Meyers                                    Assistant General Counsel
Patricia A. Michel                                   Assistant Director - Policyowner Services
Jay W. Miller                                        Vice President & Tax Counsel
Sara K. Miller                                       Vice President
</TABLE>

                                      C-8

<PAGE>   71

<TABLE>
<S>                                                <C>
Jill Mocarski                                        Associate Medical Director
Tom M. Mohr                                          Director of Policyowner Services - South
Richard C. Moore                                     Associate Actuary
Scott J. Morris                                      Assistant General Counsel & Assistant Secretary
Sharon A. Morton                                     Investment Officer
Adrian J. Mullin                                     Assistant Director - Personal Markets
Timothy P. Murphy                                    Assistant Director-Marketing
Randolph J. Musil                                    Assistant Director - Advanced Marketing
John E. Muth                                         Assistant Director - Advanced Marketing
David K. Nelson                                      Assistant General Counsel
Ronald C. Nelson                                     Director
Timothy Nelson                                       Assistant Director - Marketing
Leon W. Nesbitt                                      Vice President-Agency
Karen M. Niessing                                    Director - Policyowner Services
Daniel J. O'Meara                                    Director - Field Financial
Mary Joy O'Meara                                     Assistant Director - Advanced Marketing
Kathleen A. Oman                                     Associate Director - Information Systems
Thomas A. Pajewski                                   Investment Research Officer
Arthur V. Panighetti                                 Director - Tax Planning
Christen L. Partleton                                Associate Director - Policyowner Services
Jeffrey L. Pawlowski                                 Assistant Director - Agency Development
David W. Perez                                       Assistant General Counsel
Judith L. Perkins                                    Assistant General Counsel & Assistant Secretary
Wilson D. Perry                                      Assistant General Counsel & Assistant Secretary
Gary N. Peterson                                     Actuary
John C. Peterson                                     Director of Policyowner Services - West
Harvey W. Pogoriler                                  Assistant General Counsel
Randolph R. Powell, M.D.                             Medical Director
Mark A. Prange                                       Associate Director - Information Systems
Brian R. Pray                                        Assistant Regional Director - New Business
Thomas O. Rabenn                                     Assistant General Counsel & Assistant Secretary
David R. Remstad                                     Senior Actuary
David R. Retherford                                  Assistant Director of New Business - Central
Stephen M. Rhode                                     Assistant Director - Qualified Benefits
Richard R. Richter                                   Vice President
Daniel A. Riedl                                      Assistant General Counsel
Marcia Rimai                                         Vice President - Litigation Counsel
Kathleen M. Rivera                                   Vice President - Insurance Counsel
Faith B. Rodenkirk                                   Assistant Director - Group Marketing
James S. Rolfsmeyer                                  Assistant Director - Information Systems
Lora A. Rosenbaum                                    Director - New Business
Robert K. Roska                                      Associate Director - Information Systems
Sue M. Roska                                         Director - Systems and Services
Harry L. Ruppenthal                                  Director of Policyowner Services - East
Stephen G. Ruys                                      Assistant Director - Information Systems
Rose Kordich Sasich                                  Assistant Director of Systems
Mary Ann Schachtner                                  Director - Field Training & Development
Linda Ann Schaefer                                   Assistant Director - Marketing
Timothy G. Schaefer                                  Assistant Director - Investment Services Architecture
Thomas F. Scheer                                     Assistant General Counsel & Assistant Secretary
Carlen A. Schenk                                     Associate Director
Jane A. Schiltz                                      Vice President - Disability Income
Kathleen H. Schluter                                 Assistant General Counsel & Assistant Secretary
Calvin R. Schmidt                                    Associate Director - Information Systems
</TABLE>


                                      C-9
<PAGE>   72

<TABLE>
<S>                                                <C>
Rodd Schneider                                       Assistant General Counsel & Assistant Secretary
Sarah R. Schneider                                   Assistant Director - Corporate Project
John O. Schnorr                                      Assistant Director
Margaret R. Schoewe                                  Vice President - Information Systems
John F. Schroeder                                    Associate Director of Field Office Real Estate
Donna L. Schwartz                                    Assistant Director - Customer Service
Melva T. Seabron                                     Director - Corporate Services
Norman W. Seguin, II                                 Investment Officer - Ad Valorem Taxes
Catherine L. Shaw                                    Assistant General Counsel & Assistant Secretary
John E. Sheaffer, Jr.                                Assistant Director - Agent Development
Janet Z. Silverman                                   Director - New Business
Stephen M. Silverman                                 Assistant General Counsel
David W. Simbro                                      Managing Director - Life Marketing
Paul W. Skalecki                                     Associate Actuary
Cynthia S. Slavik                                    Assistant Director - Environmental Engineer
Landon T. Smith                                      Assistant Director - Replacements
Mark W. Smith                                        Assistant General Counsel & Assistant Secretary
Warren L. Smith, Jr.                                 Investment Officer - Architecture
Steven W. Speer                                      Director - Annuity & Mutual Fund Marketing
Robert J. Spellman, M.D.                             Vice President & Chief Medical Director
Steve P. Sperka                                      Assistant Actuary
Mark A. Stalsberg                                    Assistant Director - Agency
Barbara J. Stansberry                                Director - New Business
Bonnie L. Steindorf                                  Director - Department Operations
Steven H. Steidinger                                 Assistant Director - Marketing
Karen J. Stevens                                     Assistant General Counsel & Assistant Secretary
Steven J. Stribling                                  Associate Actuary
Stephen J. Strommen                                  Associate Actuary
Theodore H. Strupp                                   Assistant Director
Daniel J. Suprenant                                  Director - Group Disability Marketing
Victoria A. Sweigart                                 Human Resources Officer
Rachel L. Taknint                                    Assistant General Counsel & Assistant Secretary
Thomas Talajkowski                                   Assistant Director - Tax Compliance
Paul B. Tews                                         Director - Investment Planning
Deanna L. Tillisch                                   Assistant Director - Media Relations
Susan M. Tompkins                                    Director - Agency
Thomas W. Towers                                     Associate Director - Public Relations
Gloria E. Tracy                                      Assistant Director - Marketing
Linda K. Tredupp                                     Assistant Director - Information Systems
Chris G. Trost                                       Associate Actuary
Mark J. Van Cleave                                   Assistant Director of Marketing Research
Michael T. Van Grinsven                              Assistant Director - Management Development
Mary Beth Van Groll                                  Vice President - Information Systems
Gloria J. Venski                                     Associate Director - Disability Benefits
Janine L. Wagner                                     Assistant Director - Investment Services
Scott E. Wallace                                     Assistant Director - Projects
Hal W. Walter                                        Vice President
P. Andrew Ware                                       Vice President
Mary L. Wehrle-Schnell                               Associate Director - Information Systems
Daniel T. Weidner                                    Assistant Director - Information Systems
Joel S. Weiner                                       Assistant Medical Director
Ronald J. Weir                                       Associate Director - Information Systems
</TABLE>

                                      C-10
<PAGE>   73

<TABLE>
<S>                                                <C>
Kenneth R. Wentland                                  Assistant Director of Policyowner Services - East
David B. Wescoe                                      Vice President to President
Sandra D. Wesley                                     Associate Director of Special Projects
Catherine A. Wilbert                                 Assistant General Counsel & Assistant Secretary
David L. Wild                                        Director - Corporate Services
Donald R. Wilkinson                                  Vice President - Agency
Jeffrey B. Williams                                  Risk Manager
John K. Wilson                                       Director - Personal Markets
Penelope A. Woodcock                                 Associate Director - Benefit Systems
Richard W. Woody                                     Assistant Director - Agency
Stanford A. Wynn                                     Assistant Director - Advanced Marketing
Catherine M. Young                                   Assistant General Counsel & Assistant Secretary
Michael L. Youngman                                  Vice President - Legislative Representative
James A. Youngquist                                  Associate Actuary
Richard S. Zakrzewski                                Associate Research Officer
John Zao                                             Assistant Director - Information Systems
Diana M. Zawada                                      Associate Director
Rick T. Zehner                                       Director - Corporate Planning
Patricia A. Zimmermann                               Investment Officer - Real Estate Systems
Ray Zimmermann                                       Director - LINK Information Network
Philip R. Zwieg                                      Vice President - Technical Support
Robert E. Zysk                                       Director - Tax Compliance
</TABLE>

The business addresses for all of the executive officers and other officers is
720 East Wisconsin Avenue, Milwaukee, Wisconsin 53202.

Item 26.  Persons Controlled By or Under Common Control with the Depositor or
Registrant

         The subsidiaries of The Northwestern Mutual Life Insurance Company
("Northwestern Mutual"), as of December 31, 1999 are set forth on pages C-12 and
C-13. In addition to the subsidiaries set forth pages on C-12 and C-13, the
following separate investment accounts (which include the Registrant) may be
deemed to be either controlled by, or under common control with, Northwestern
Mutual:

         1.       NML Variable Annuity Account A
         2.       NML Variable Annuity Account B
         3.       NML Variable Annuity Account C
         4.       Northwestern Mutual Variable Life Account

         Northwestern Mutual Series Fund, Inc. and Russell Insurance Funds (the
"Funds"), shown on page C-12 as subsidiaries of Northwestern Mutual, are
investment companies registered under the Investment Company Act of 1940,
offering their shares to the separate accounts identified above; and the shares
of the Funds held in connection with certain of the accounts are voted by
Northwestern Mutual in accordance with voting instructions obtained from the
persons who own, or are receiving payments under, variable annuity contracts or
variable life insurance policies issued in connection with the accounts, or in
the same proportions as the shares which are so voted.

                                      C-11

<PAGE>   74


                            NML CORPORATE STRUCTURE*
                            (AS OF DECEMBER 31, 1999)

THE NORTHWESTERN MUTUAL LIFE INSURANCE COMPANY
  General Account
  NML Variable Annuity Account A
  NML Variable Annuity Account B
  NML Variable Annuity Account C
  NML Group Annuity Separate Account
  NML Variable Life Account
  Eiger Corporation - 100%
  Frank Russell Company and its subsidiaries - 100%
  Bradford, Inc. - 100%
  NML/Tallahassee, Inc. - 100%
  Northwestern Investment Management Company - 100%
  Northwestern Mutual Las Vegas, Inc. - 100%
  Northwestern Long Term Care Insurance Company - 100%
  Northwestern International Holdings, Inc. - 100%
  Northwestern Foreign Holdings B.V. - 100%
  Saskatoon Centre, Limited - 100% (inactive)
  Northwestern Mutual Series Fund, Inc. (and its 11 portfolios) - 100%
  Russell Insurance Funds (and its 5 funds) - 70.8%
  Mason Street Funds, Inc. (and its 11 funds) - 77.03%
  MGIC Investment Corporation - 11%. MGIC holds 100% of the voting stock of the
   following:
    Mortgage Guaranty Reinsurance Corporation, MGIC, MGIC Reinsurance
    Corporation of Wisconsin, MGIC Mortgage Insurance Corporation, and various
    subsidiaries.
  Baird Financial Corporation - 80%. Baird Financial Corporation holds 80% of
    the voting stock of Robert W. Baird & Co., Incorporated and various
    subsidiaries.
  Northwestern Mutual Investment Services, LLC - 100%
  Northwestern Reinsurance Holdings N.V. - 100%
  Northwestern Financial Group LLC - 100% (inactive)
  NML - CBO, LLC - 49%

<TABLE>
<S>                                            <C>
NML REAL ESTATE HOLDINGS, LLC - 100%
The Grand Avenue Corporation - 98.54%            Mitchell, Inc. - 100%
Marina Pacific, Ltd. - 100%                      Cass Corporation - 100%
Solar Resources, Inc. - 100%                     Burgundy, Inc. - 100%
Rocket Sports, Inc. - 100% (inactive)            Amber, Inc. - 100%
Summit Sports, Inc. - 100% (inactive)            Olive, Inc. - 100%
Greenway Sports, Inc. - 100% (inactive)          Bayridge, Inc. - 100%
RE Corporation - 100%                            Ryan, Inc. - 100%
INV Corp. - 100%                                 Pembrook, Inc. - 100%
Buffalo Promotions, Inc. - 100% (inactive)       PBClub, Inc. - 100%
NW Greenway #1 - 100% (inactive)                 Diversey, Inc. - 100%
NW Greenway #9 - 100% (inactive)                 Larkin, Inc. - 100% (inactive)
Logan, Inc. - 100%                               Russet, Inc. - 100% (inactive)
</TABLE>

* Except for MGIC Investment Corporation and its subsidiaries, includes all NML
mutual funds and other corporations of which 50% or more voting power is
controlled by NML.


                                      C-12
<PAGE>   75


                       NML CORPORATE STRUCTURE, CONTINUED*
                            (AS OF DECEMBER 31, 1999)


NML SECURITIES HOLDINGS, LLC-100%

<TABLE>
<S>                                                               <C>
    NW Pipeline, Inc. - 100%                                       Kristina International Sales, Inc. - 100%
    Painted Rock Development Corporation - 100%                    NML/Mid Atlantic, Inc. - 100%
    NML Development Corporation - 100%                             KerryAnne International Sales, Inc. - 100%
    Stadium and Arena Management, Inc. - 100%                      Regina International Sales, Inc. - 100%
    Carlisle Ventures, Inc. - 100%
    Park Forest Northeast, Inc. - 100%
    Travers International Sales, Inc. - 100%
    Highbrook International Sales, Inc. - 100%
    Elderwood International Sales, Inc. - 100%
    Mallon International Sales, Inc. - 100%
    Higgins, Inc. - 100%
    Hobby, Inc. - 100%
    Baraboo, Inc. - 100%
    Elizabeth International Sales, Inc. - 100%
    Sean International Sales, Inc. - 100%
    Alexandra International Sales, Inc. - 100%
    Brian International Sales, Inc. - 100%
    Jack International Sales, Inc. - 100%
    Brendan International Sales, Inc. - 100%
    Justin International FSC, Inc. - 100%
    Mason & Marshall, Inc. - 100%
    North Van Buren, Inc. - 100%
    Northwestern Mutual Life
      International, Inc. - 100%
    White Oaks, Inc. - 100%
    Hazel, Inc. - 100%
    Maroon, Inc. - 100%
    Coral, Inc. - 100%
    Lydell, Inc. - 100%
    Klode, Inc. - 100%
    Chateau, Inc. - 100% (inactive)
    Lake Bluff, Inc. - 100% (inactive)
    Nicolet, Inc. - 100% (inactive)
    Tupelo, Inc. - 100% (inactive)
</TABLE>


* Except for MGIC Investment Corporation and its subsidiaries, includes all NML
mutual funds and other corporations of which 50% or more voting power is
controlled by NML.

                                      C-13

<PAGE>   76


Item 27. Number of Contract Owners

         As of February 29, 2000, 16,690 variable annuity contracts issued in
connection with NML Variable Annuity Account A were outstanding. All such
contracts were issued as contracts for plans qualifying for special treatment
under various provisions of the Internal Revenue Code.

Item 28. Indemnification

         That portion of the By-laws of Northwestern Mutual relating to
indemnification of Trustees and officers is set forth in full in Article VII of
the By-laws of Northwestern Mutual, amended by resolution and previously filed
as an exhibit to the Registration Statement.

Item 29. Principal Underwriters

         (a) Northwestern Mutual Investment Services, LLC ("NMIS"), the
broker-dealer subsidiary of Northwestern Mutual, may be considered the principal
underwriter currently distributing securities of the Registrant. NMIS is also
co-depositor, and may be considered the principal underwriter, for NML Variable
Annuity Account B and Northwestern Mutual Variable Life Account, separate
investment accounts of Northwestern Mutual registered under the Investment
Company Act of 1940 as unit investment trusts. In addition NMIS is the
investment adviser for Northwestern Mutual Series Fund, Inc.

         (b) The directors and officers of NMIS are as follows:

<TABLE>
<CAPTION>
Name                                                                            Position
- ----                                                                            --------
<S>                                                      <C>
Maria J. Avila                                            Assistant Treasurer
Barbara Bay                                               Assistant Director, Equity Compliance, NMIS Office of
                                                            Supervisory Jurisdiction
Deborah A. Beck                                           Director and Vice President, Variable Life Administration
William H. Beckley                                        Executive Vice President, Sales
Peter W. Bruce                                            Director
Thomas A. Carroll                                         Vice President - Common Stocks
Walter J. Chossek                                         Treasurer
Barbara E. Courtney                                       Assistant Treasurer
Jefferson V. De Angelis                                   Vice President - Fixed Income Securities
Mark G. Doll                                              Executive Vice President, Investment Advisory Services
James R. Eben                                             Assistant Secretary
Richard L. Hall                                           Vice President, Variable Life Marketing
Lisa M. Heise                                             Assistant Director, Equity Compliance, NMIS Office of
                                                            Supervisory Jurisdiction
Laila V. Hick                                             Assistant Director, Equity Compliance, NMIS Office of
                                                            Supervisory Jurisdiction
Beatrice C. Kmiec                                         Assistant Vice President, Variable Life Administration
Merrill C. Lundberg                                       Secretary
Meridee J. Maynard                                        President and CEO
Allan J. McDonell                                         Vice President and Chief Compliance Officer
Ignatius L. Smetek                                        Vice President - Common Stocks
Leonard F. Stecklein                                      Vice President - Trust Services
Steven P. Swanson                                         Vice President
Carla A. Thoke                                            Director, Equity Compliance, NMIS Office of Supervisory
                                                            Jurisdiction
J. Edwards Tippetts                                       Vice President, Sales Support
Julie Van Cleave                                          Vice President - Common Stocks
Patricia L. Van Kampen                                    Vice President - Common Stocks
</TABLE>


                                      C-14
<PAGE>   77

<TABLE>
<S>                                                     <C>
William R. Walker                                         Vice President
Robert J. Ziegler                                         Assistant Treasurer
Edward J. Zore                                            Director
</TABLE>

The address for each director and officer of NMIS is 720 East Wisconsin Avenue,
Milwaukee, Wisconsin 53202.

         (c) During 1999 life insurance agents of Northwestern Mutual who are
also registered representatives of NMIS received commissions, including general
agent overrides, in the aggregate amount of $2,679,128 for sales of variable
annuity contracts, and interests therein, issued in connection with the
Registrant. NMIS received compensation for its investment advisory services from
Northwestern Mutual Series Fund, Inc., the investment company in which assets of
the Registrant are invested.

Item 30. Location of Accounts and Records

         All accounts, books or other documents required to be maintained in
connection with the Registrant's operations are maintained in the physical
possession of Northwestern Mutual at 720 East Wisconsin Avenue, Milwaukee,
Wisconsin 53202.

Item 31. Management Services

         There are no contracts, other than those referred to in Part A or Part
B of this Registration Statement, under which management-related services are
provided to the Registrant and pursuant to which total payments of $5,000 or
more were made during any of the last three fiscal years.

Item 32. Undertakings

         (a) The Registrant undertakes to file a post-effective amendment to
this Registration Statement as frequently as is necessary to ensure that the
audited financial statements in the Registration Statement are never more than
16 months old for so long as payments under the variable annuity contracts may
be accepted.

         (b) The Registrant undertakes to include either (1) as part of any
application to purchase a contract offered by the prospectus, a space that an
applicant can check to request a Statement of Additional Information, or (2) a
post card or similar written communication affixed to or included in the
prospectus that the applicant can remove to send for a Statement of Additional
Information.

         (c) The Registrant undertakes to deliver any Statement of Additional
Information and any financial statements required to be made available under
this Form promptly upon written or oral request.

         (d) Reference is made to the indemnification provisions disclosed in
response to Item 28. 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 registered securities, 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.

                                      C-15
<PAGE>   78


                                   SIGNATURES

         As required by the Securities Act of 1933, the Registrant, NML Variable
Annuity Account A, certifies that it meets all of the requirements for
effectiveness of this Amended Registration Statement pursuant to Rule 485 (b)
under the Securities Act of 1933 and has duly caused this Amended Registration
Statement to be signed on its behalf, in the City of Milwaukee, and State of
Wisconsin, on the 23rd day of March, 2000.

                                               NML VARIABLE ANNUITY ACCOUNT A
                                               (Registrant)

                                               By THE NORTHWESTERN MUTUAL LIFE
                                                  INSURANCE COMPANY
                                                  (Depositor)

Attest: JOHN M. BREMER                         By: JAMES D. ERICSON
        --------------------------------          ------------------------------
        John M. Bremer, Executive Vice             James D. Ericson, President
         President, General Counsel                  and Chief Executive Officer
         and Secretary

         As required by the Securities Act of 1933, this Amended Registration
Statement has been signed by the depositor on the 23rd day of March, 2000.

                                               THE NORTHWESTERN MUTUAL LIFE
                                               INSURANCE COMPANY
                                               (Depositor)

Attest: JOHN M. BREMER                         By:  JAMES D. ERICSON
        --------------------------------          ------------------------------
        John M. Bremer, Executive Vice             James D. Ericson, President
          President, General Counsel                 and Chief Executive Officer
          and Secretary

         As required by the Securities Act of 1933, this Amended Registration
Statement has been signed by the following persons in the capacities with the
depositor and on the dates indicated:

<TABLE>
<CAPTION>
Signature                                   Title
- ---------                                   -----
<S>                                        <C>                             <C>

                                            Trustee, President and
JAMES D. ERICSON                            Principal Executive and
- ----------------------------------------    Financial Officer
James D. Ericson


GARY E. LONG                                Vice President, Controller
- ----------------------------------------    and Principal Accounting
Gary E. Long                                Officer


EDWARD J. ZORE                              Trustee                            Dated
- ----------------------------------------                                   March  23, 2000
Edward J. Zore


HAROLD B. SMITH*                            Trustee
- ----------------------------------------
Harold B. Smith
</TABLE>


                                      C-16
<PAGE>   79


<TABLE>
<S>                                        <C>                             <C>
J. THOMAS LEWIS*                               Trustee
- ----------------------------------------
J. Thomas Lewis


PATRICIA ALBJERG GRAHAM*                       Trustee
- ----------------------------------------
Patricia Albjerg Graham*


R. QUINTUS ANDERSON*                           Trustee
- ----------------------------------------
R. Quintus Anderson


STEPHEN F. KELLER*                             Trustee
- ----------------------------------------
Stephen F. Keller


PIERRE S. du PONT*                             Trustee
- ----------------------------------------
Pierre S. du Pont


J. E. GALLEGOS*                                Trustee                         Dated
- ----------------------------------------                                   March 23, 2000
J. E. Gallegos


KATHRYN D. WRISTON*                            Trustee
- ----------------------------------------
Kathryn D. Wriston


BARRY L. WILLIAMS*                             Trustee
- ----------------------------------------
Barry L. Williams


GORDON T. BEAHAM III*                          Trustee
- ----------------------------------------
Gordon T. Beaham III


DANIEL F. McKEITHAN, JR.*                      Trustee
- ----------------------------------------
Daniel F. McKeithan, Jr.


EDWARD E. BARR*                                Trustee
- ----------------------------------------
Edward E. Barr


ROBERT C. BUCHANAN*                            Trustee
- ----------------------------------------
Robert C. Buchanan


SHERWOOD H. SMITH, JR.*                        Trustee
- ----------------------------------------
Sherwood H. Smith, Jr.


H. MASON SIZEMORE, JR.*                        Trustee
- ----------------------------------------
H. Mason Sizemore, Jr.
</TABLE>

                                      C-17
<PAGE>   80


<TABLE>
<S>                                        <C>                             <C>
JOHN J. STOLLENWERK*                           Trustee
- ----------------------------------------
John J. Stollenwerk


GEORGE A. DICKERMAN*                           Trustee
- ----------------------------------------
George A. Dickerman


GUY A. OSBORN*                                 Trustee                         Dated
- ----------------------------------------                                   March 23, 2000
Guy A. Osborn


JOHN E. STEURI*                                Trustee
- ----------------------------------------
John E. Steuri


STEPHEN N. GRAFF*                              Trustee
- ----------------------------------------
Stephen N. Graff


BARBARA A. KING*                               Trustee
- ----------------------------------------
Barbara A. King


TIMOTHY D. PROCTOR*                            Trustee
- ----------------------------------------
Timothy D. Proctor


PETER M. SOMMERHAUSER*                         Trustee
- ----------------------------------------
Peter M. Sommerhauser

*By:  JAMES D. ERICSON
- ----------------------------------------
      James D. Ericson, Attorney in Fact,
      pursuant to the Power of Attorney
      previously filed on January 27, 2000
</TABLE>


                                      C-18
<PAGE>   81
                                  EXHIBIT INDEX
                          EXHIBITS FILED WITH FORM N-4
                        POST-EFFECTIVE AMENDMENT NO. 2 TO
             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
                                       FOR
                         NML VARIABLE ANNUITY ACCOUNT A

Exhibit Number                         Exhibit Name
- --------------                         ------------


Exhibit B(10)                          Consent of PricewaterhouseCoopers LLP




<PAGE>   1

                                  Exhibit B(10)

                       CONSENT OF INDEPENDENT ACCOUNTANTS




         We hereby consent to the use in the Statement of Additional Information
constituting part of this Post-Effective Amendment No. 2 to the registration
statement on Form N-4 (the "Registration Statement") of our report dated January
24, 2000, relating to the financial statements of The Northwestern Mutual Life
Insurance Company, and of our report dated January 27, 2000, relating to the
financial statements of NML Variable Annuity Account A, which appear in such
Statement of Additional Information, and to the incorporation by reference of
such reports into the Prospectus which constitutes part of this Registration
Statement. We also consent to the reference to us under the heading "Experts" in
such Statement of Additional Information.













PricewaterhouseCoopers LLP


Milwaukee, Wisconsin
March 27, 2000




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