MORGAN STANLEY DEAN WITTER TAX EXEMPT SECURITIES TRUST
497, 2000-04-10
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<PAGE>


                                              Filed Pursuant to Rule 497(b)
                                              Registration File No.: 333-31582

          MORGAN STANLEY DEAN WITTER MULTI-STATE MUNICIPAL SERIES TRUST
                                MINNESOTA SERIES

                             TWO WORLD TRADE CENTER
                            NEW YORK, NEW YORK 10048
                                 (800) 869-NEWS

                    NOTICE OF SPECIAL MEETING OF SHAREHOLDERS
                            TO BE HELD JUNE 22, 2000

TO THE SHAREHOLDERS OF THE MINNESOTA SERIES, A SERIES OF MORGAN STANLEY DEAN
WITTER MULTI-STATE MUNICIPAL SERIES TRUST :

     Notice is hereby given of a Special Meeting of the Shareholders of the
Minnesota Series ("Minnesota Series"), a portfolio of Morgan Stanley Dean
Witter Multi-State Municipal Series Trust ("Multi-State"), to be held in
Conference Room A, Forty-Fourth Floor, Two World Trade Center, New York, New
York 10048, at 10:00 A.M., New York time, on June 22, 2000, and any
adjournments thereof (the "Meeting"), for the following purposes:

1.   To consider and vote upon an Agreement and Plan of Reorganization, dated
     January 26, 2000 (the "Reorganization Agreement"), between Multi-State, on
     behalf of Minnesota Series, and Morgan Stanley Dean Witter Tax-Exempt
     Securities Trust ("Tax-Exempt"), pursuant to which substantially all of the
     assets of Minnesota Series would be combined with those of Tax-Exempt and
     shareholders of Minnesota Series would become shareholders of Tax-Exempt
     receiving Class D shares of Tax-Exempt with a value equal to the value of
     their holdings in Minnesota Series (the "Reorganization"); and

2.   To act upon such other matters as may properly come before the Meeting.

     The Reorganization is more fully described in the accompanying Proxy
Statement and Prospectus and a copy of the Reorganization Agreement is attached
as Exhibit A thereto. Shareholders of record at the close of business on March
17, 2000 are entitled to notice of, and to vote at, the Meeting. Please read
the Proxy Statement and Prospectus carefully before telling us, through your
proxy or in person, how you wish your shares to be voted. Alternatively, if you
are eligible to vote telephonically by touchtone telephone or electronically on
the Internet (as discussed in the enclosed Proxy Statement) you may do so in
lieu of attending the Meeting in person. THE BOARD OF TRUSTEES OF MULTI-STATE
RECOMMENDS YOU VOTE IN FAVOR OF THE REORGANIZATION. WE URGE YOU TO SIGN, DATE
AND MAIL THE ENCLOSED PROXY PROMPTLY.

                                       By Order of the Board of Trustees,


                                       BARRY FINK,
                                       Secretary

April 7, 2000

- --------------------------------------------------------------------------------
YOU CAN HELP AVOID THE NECESSITY AND EXPENSE OF SENDING FOLLOW-UP LETTERS TO
ENSURE A QUORUM BY PROMPTLY RETURNING THE ENCLOSED PROXY. IF YOU ARE UNABLE TO
BE PRESENT IN PERSON, PLEASE FILL IN, SIGN AND RETURN THE ENCLOSED PROXY IN
ORDER THAT THE NECESSARY QUORUM BE REPRESENTED AT THE MEETING. THE ENCLOSED
ENVELOPE REQUIRES NO POSTAGE IF MAILED IN THE UNITED STATES. AS DISCUSSED IN THE
ENCLOSED PROXY STATEMENT, CERTAIN SHAREHOLDERS WILL BE ABLE TO VOTE
TELEPHONICALLY BY TOUCHTONE TELEPHONE OR ELECTRONICALLY ON THE INTERNET BY
FOLLOWING INSTRUCTIONS ON THEIR PROXY CARDS OR ON THE ENCLOSED VOTING
INFORMATION CARD.
- --------------------------------------------------------------------------------
<PAGE>

                           MORGAN STANLEY DEAN WITTER
                           TAX-EXEMPT SECURITIES TRUST

                TWO WORLD TRADE CENTER, NEW YORK, NEW YORK 10048
                                 (800) 869-NEWS

                          ACQUISITION OF THE ASSETS OF
                        THE MINNESOTA SERIES, A SERIES OF
          MORGAN STANLEY DEAN WITTER MULTI-STATE MUNICIPAL SERIES TRUST

                    BY AND IN EXCHANGE FOR CLASS D SHARES OF
             MORGAN STANLEY DEAN WITTER TAX-EXEMPT SECURITIES TRUST

     This Proxy Statement and Prospectus is being furnished to shareholders of
the Minnesota Series ("Minnesota Series"), a portfolio of Morgan Stanley Dean
Witter Multi-State Municipal Series Trust ("Multi-State"), in connection with
an Agreement and Plan of Reorganization, dated January 26, 2000 (the
"Reorganization Agreement"), pursuant to which substantially all the assets of
Minnesota Series will be combined with those of Morgan Stanley Dean Witter
Tax-Exempt Securities Trust ("Tax-Exempt") in exchange for Class D shares of
Tax-Exempt (the "Reorganization"). As a result of this transaction,
shareholders of Minnesota Series will become shareholders of Tax-Exempt and
will receive Class D shares of Tax-Exempt with a value equal to the value of
their holdings in Minnesota Series. The terms and conditions of this
transaction are more fully described in this Proxy Statement and Prospectus and
in the Reorganization Agreement between Multi-State, on behalf of Minnesota
Series, and Tax-Exempt, attached hereto as Exhibit A. The address of Minnesota
Series is that of Tax-Exempt set forth above. This Proxy Statement also
constitutes a Prospectus of Tax-Exempt, which is dated April 3, 2000, filed by
Tax-Exempt with the Securities and Exchange Commission (the "Commission") as
part of its Registration Statement on Form N-14 (the "Registration Statement").

     Tax-Exempt is an open-end diversified management investment company whose
investment objective is to provide a high level of current income exempt from
federal income tax consistent with preservation of capital. The fund seeks to
achieve its objective by investing at least 80% of its assets in securities
that pay interest exempt from federal income taxes.

     This Proxy Statement and Prospectus sets forth concisely information about
Tax-Exempt that shareholders of Minnesota Series should know before voting on
the Reorganization Agreement. A copy of the Prospectus for Tax-Exempt dated
February 24, 2000, is attached as Exhibit B and incorporated herein by
reference. Also enclosed and incorporated herein by reference is Tax-Exempt's
Annual Report for the fiscal year ended December 31, 1999. A Statement of
Additional Information relating to the Reorganization, described in this Proxy
Statement and Prospectus (the "Additional Statement"), dated April 3, 2000, has
been filed with the Commission and is also incorporated herein by reference.
Also incorporated herein by reference are Multi-State's Prospectus, dated
February 25, 2000, and Annual Report for its fiscal year ended November 30,
1999. Such documents are available without charge by calling (800) 869-NEWS
(TOLL FREE).

Investors are advised to read and retain this Proxy Statement and Prospectus
for future reference.

THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION, NOR HAS THE SECURITIES
AND EXCHANGE COMMISSION OR ANY STATE SECURITIES COMMISSION PASSED ON THE
ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS
A CRIMINAL OFFENSE.

           THIS PROXY STATEMENT AND PROSPECTUS IS DATED APRIL 3, 2000.
<PAGE>

                                TABLE OF CONTENTS
                         PROXY STATEMENT AND PROSPECTUS

<TABLE>
<CAPTION>
                                                                                              PAGE
                                                                                              ----
<S>                                                                                            <C>
INTRODUCTION .............................................................................      1
  General ................................................................................      1
  Record Date; Share Information .........................................................      1
  Proxies ................................................................................      2
  Expenses of Solicitation ...............................................................      2
  Vote Required ..........................................................................      3
SYNOPSIS .................................................................................      3
  The Reorganization .....................................................................      3
  Fee Table ..............................................................................      4
  Tax Consequences of the Reorganization .................................................      6
  Comparison of Minnesota Series and Tax-Exempt ..........................................      6
PRINCIPAL RISK FACTORS ...................................................................      8
THE REORGANIZATION .......................................................................      9
  The Proposal ...........................................................................      9
  The Board's Consideration ..............................................................      9
  The Reorganization Agreement ...........................................................     10
  Tax Aspects of the Reorganization ......................................................     12
  Description of Shares ..................................................................     13
  Capitalization Table (unaudited) .......................................................     13
  Appraisal Rights .......................................................................     13
COMPARISON OF INVESTMENT OBJECTIVES, POLICIES AND RESTRICTIONS ...........................     13
  Investment Objectives and Policies .....................................................     13
  Investment Restrictions ................................................................     15
ADDITIONAL INFORMATION ABOUT MINNESOTA SERIES AND TAX-EXEMPT .............................     15
  General ................................................................................     15
  Financial Information ..................................................................     15
  Management .............................................................................     15
  Description of Securities and Shareholder Inquiries ....................................     15
  Dividends, Distributions and Taxes .....................................................     15
  Purchases, Repurchases and Redemptions .................................................     16
MANAGEMENT'S DISCUSSION OF FUND PERFORMANCE ..............................................     16
FINANCIAL STATEMENTS AND EXPERTS .........................................................     16
LEGAL MATTERS ............................................................................     16
AVAILABLE INFORMATION ....................................................................     16
OTHER BUSINESS ...........................................................................     17
Exhibit A - Agreement and Plan of Reorganization, dated January 26, 2000, by and between
 Multi-State, on behalf of Minnesota Series, and Tax-Exempt ..............................    A-1
Exhibit B - Prospectus of Tax-Exempt dated February 24, 2000 .............................    B-1
</TABLE>

<PAGE>

          MORGAN STANLEY DEAN WITTER MULTI-STATE MUNICIPAL SERIES TRUST
                                MINNESOTA SERIES
                             TWO WORLD TRADE CENTER
                            NEW YORK, NEW YORK 10048
                                 (800) 869-NEWS

                              --------------------
                         PROXY STATEMENT AND PROSPECTUS
                              --------------------

                         SPECIAL MEETING OF SHAREHOLDERS
                            TO BE HELD JUNE 22, 2000

                                  INTRODUCTION

GENERAL

     This Proxy Statement and Prospectus is being furnished to the shareholders
of the Minnesota Series ("Minnesota Series"), a portfolio of Morgan Stanley
Dean Witter Multi-State Municipal Series Trust ("Multi-State"), an open-end
non-diversified management investment company, in connection with the
solicitation by the Board of Trustees of Multi-State (the "Board") of proxies
to be used at the Special Meeting of Shareholders of Minnesota Series to be
held in Conference Room A, Forty-Fourth Floor, Two World Trade Center, New
York, New York 10048 at 10:00 A.M., New York time, on June 22, 2000, and any
adjournments thereof (the "Meeting"). It is expected that the mailing of this
Proxy Statement and Prospectus will be made on or about April 12, 2000.

     At the Meeting, Minnesota Series shareholders ("Shareholders") will
consider and vote upon an Agreement and Plan of Reorganization, dated January
26, 2000 (the "Reorganization Agreement"), between Multi-State, on behalf of
Minnesota Series, and Morgan Stanley Dean Witter Tax-Exempt Securities Trust
("Tax-Exempt") pursuant to which substantially all of the assets of Minnesota
Series will be combined with those of Tax-Exempt in exchange for Class D shares
of Tax-Exempt. As a result of this transaction, Shareholders will become
shareholders of Tax-Exempt and will receive Class D shares of Tax-Exempt equal
to the value of their holdings in Minnesota Series on the date of such
transaction (the "Reorganization"). The Class D shares to be issued by
Tax-Exempt pursuant to the Reorganization (the "Tax-Exempt Shares") will be
issued at net asset value without an initial sales charge. Further information
relating to Tax-Exempt is set forth herein and in Tax-Exempt's current
Prospectus, dated February 24, 2000 ("Tax-Exempt's Prospectus"), attached to
this Proxy Statement and Prospectus and incorporated herein by reference.

     The information concerning Minnesota Series contained herein has been
supplied by Multi-State and the information concerning Tax-Exempt contained
herein has been supplied by Tax-Exempt.

RECORD DATE; SHARE INFORMATION

     The Board has fixed the close of business on March 17, 2000 as the record
date (the "Record Date") for the determination of the Shareholders entitled to
notice of, and to vote at, the Meeting. As of the Record Date, there were
629,254.273 shares of Minnesota Series issued and outstanding. Shareholders on
the Record Date are entitled to one vote per share on each matter submitted to
a vote at the Meeting. A majority of the outstanding shares entitled to vote,
represented in person or by proxy, will constitute a quorum at the Meeting.

                                       1
<PAGE>

     The following persons were known to own of record or beneficially 5% or
more of the outstanding shares of Minnesota Series as of the Record Date: Odd
Kermit Rovick TTEE for the Rovick Revocable Living TR under agreement DTD
8/26/94, 5501 Village Drive, Apt. 305, Edina, MN 55439-1949 (10.3%). As of the
Record Date, the trustees and officers of Multi-State, as a group, owned less
than 1% of the outstanding shares of Minnesota Series.

     The following persons were known to own of record or beneficially 5% or
more of the outstanding shares of a Class of Tax-Exempt as of the Record Date:
Class A -- Morgan Stanley Dean Witter TR FSB, TTEE FBO Richard K. Allen and
Dorothy B. Allen REV Trust Husband and Wife Share, P.O. Box 503, Jersey City,
NJ 07311 (6.1%); Howard C. Kauffmann & Suzanne M. Kauffmann JT TEN, 2724
Peachtree Road NW, Atlanta, GA 30305-2978 (5.9%); Sylvia Corcoran and Edward V.
Corcoran JT TEN, 5355 Nautilus Drive, Cape Coral, FL 33904-5973 (5.6%); Robert
T. Smylie, 2512 Metropolitan Drive, Trevose, PA 19053-6738 (5.6%); Sharon R.
Frank, 338 Waycliffe North, Wayzata, MN 55391-1390 (5.5%). Class C -- Danilo F.
Piccinini & Lola Piccinini JT TEN, P.O. Box 5307, Incline Vlg., NV 89450-5307
(6.0%). As of the Record Date, the trustees and officers of Tax-Exempt, as a
group, owned less than 1% of the outstanding shares of Tax-Exempt.

PROXIES

     The enclosed form of proxy, if properly executed and returned, will be
voted in accordance with the choice specified thereon. The proxy will be voted
in favor of the Reorganization Agreement unless a choice is indicated to vote
against or to abstain from voting on the Reorganization Agreement. The Board
knows of no business, other than that set forth in the Notice of Special
Meeting of Shareholders, to be presented for consideration at the Meeting.
However, the proxy confers discretionary authority upon the persons named
therein to vote as they determine on other business, not currently
contemplated, which may come before the Meeting. Abstentions and, if
applicable, broker "non-votes" will not count as votes in favor of the
Reorganization Agreement, and broker "non-votes" will not be deemed to be
present at the meeting for purposes of determining whether the Reorganization
Agreement has been approved. Broker "non-votes" are shares held in street name
for which the broker indicates that instructions have not been received from
the beneficial owners or other persons entitled to vote and for which the
broker does not have discretionary voting authority. If a Shareholder executes
and returns a proxy but fails to indicate how the votes should be cast, the
proxy will be voted in favor of the Reorganization Agreement. The proxy may be
revoked at any time prior to the voting thereof by: (i) delivering written
notice of revocation to the Secretary of Multi-State at Two World Trade Center,
New York, New York 10048; (ii) attending the Meeting and voting in person; or
(iii) completing and returning a new proxy (whether by mail or, as discussed
below, by touchtone telephone or the Internet) (if returned and received in
time to be voted). Attendance at the Meeting will not in and of itself revoke a
proxy.

     In the event that the necessary quorum to transact business or the vote
required to approve or reject the Reorganization Agreement is not obtained at
the Meeting, the persons named as proxies may propose one or more adjournments
of the Meeting to permit further solicitation of proxies. Any such adjournment
will require the affirmative vote of the holders of a majority of shares of
Minnesota Series present in person or by proxy at the Meeting. The persons
named as proxies will vote in favor of such adjournment those proxies which
they are entitled to vote in favor of the Reorganization Agreement and will
vote against any such adjournment those proxies required to be voted against
the Reorganization Agreement.

EXPENSES OF SOLICITATION

     The expenses of this solicitation, including the cost of preparing and
mailing this Proxy Statement and Prospectus, are expected to approximate
$30,000, of which $15,000 will be borne by Morgan Stanley Dean Witter Advisors
Inc. ("MSDW Advisors" or the "Investment Manager") and $15,000 will be borne by

                                       2
<PAGE>

Minnesota Series. Minnesota Series and Tax-Exempt will bear all of their
respective other expenses associated with the Reorganization. In addition to
the solicitation of proxies by mail, proxies may be solicited by officers of
Multi-State, and officers and regular employees of MSDW Advisors and Morgan
Stanley Dean Witter Trust FSB ("MSDW Trust"), an affiliate of MSDW Advisors,
personally or by mail, telephone, telegraph or otherwise, without compensation
therefor. Brokerage houses, banks and other fiduciaries may be requested to
forward soliciting material to the beneficial owners of shares and to obtain
authorization for the execution of proxies.

     Shareholders whose shares are registered with MSDW Trust will be able to
vote their shares by touchtone telephone or by Internet by following the
instructions on the proxy card or on the Voting Information Card accompanying
this Proxy Statement and Prospectus. To vote by touchtone telephone,
Shareholders can call the toll-free number 1-800-690-6903. To vote by Internet,
Shareholders can access the websites www.msdwt.com or www.proxyvote.com.
Telephonic and Internet voting with MSDW Trust presently are not available to
Shareholders whose shares are held in street name.

     In certain instances, MSDW Trust, an affiliate of MSDW Advisors, may call
Shareholders to ask if they would be willing to have their votes recorded by
telephone. The telephone voting procedure is designed to authenticate
Shareholders' identities, to allow Shareholders to authorize the voting of
their shares in accordance with their instructions and to confirm that their
instructions have been recorded properly. No recommendation will be made as to
how a Shareholder should vote on the Reorganization Agreement other than to
refer to the recommendation of the Board. Multi-State, on behalf of Minnesota
Series, has been advised by counsel that these procedures are consistent with
the requirements of applicable law. Shareholders voting by telephone in this
manner will be asked for their social security number or other identifying
information and will be given an opportunity to authorize proxies to vote their
shares in accordance with their instructions. To ensure that the Shareholders'
instructions have been recorded correctly, they will receive a confirmation of
their instructions in the mail. A special toll-free number set forth in the
confirmation will be available in case the information contained in the
confirmation is incorrect. Although a Shareholder's vote may be taken by
telephone, each Shareholder will receive a copy of this Proxy Statement and
Prospectus and may vote by mail using the enclosed proxy card or by touchtone
telephone or the Internet as set forth above. The last proxy vote received in
time to be voted, whether by proxy card, touchtone telephone or Internet, will
be the vote that is counted and will revoke all previous votes by the
Shareholder.

VOTE REQUIRED

     Approval of the Reorganization Agreement by the Shareholders requires the
affirmative vote of a majority (i.e., more than 50%) of the shares of Minnesota
Series represented in person or by proxy and entitled to vote at the Meeting,
provided a quorum is present at the Meeting. If the Reorganization Agreement is
not approved by Shareholders, Minnesota Series will continue in existence and
the Board will consider alternative actions.

                                   SYNOPSIS

     The following is a synopsis of certain information contained in or
incorporated by reference in this Proxy Statement and Prospectus. This synopsis
is only a summary and is qualified in its entirety by the more detailed
information contained or incorporated by reference in this Proxy Statement and
Prospectus and the Reorganization Agreement. Shareholders should carefully
review this Proxy Statement and Prospectus and Reorganization Agreement in
their entirety and, in particular, Tax-Exempt's Prospectus, which is attached
to this Proxy Statement and incorporated herein by reference.

THE REORGANIZATION

     The Reorganization Agreement provides for the transfer of substantially
all the assets of Minnesota Series, subject to stated liabilities, to
Tax-Exempt in exchange for the Tax-Exempt Shares. The aggregate net asset

                                       3
<PAGE>

value of the Tax-Exempt Shares issued in the exchange will equal the aggregate
value of the net assets of Minnesota Series received by Tax-Exempt. On or after
the closing date scheduled for the Reorganization (the "Closing Date"),
Minnesota Series will distribute the Tax-Exempt Shares received by Minnesota
Series to Shareholders as of the Valuation Date (as defined below under "The
Reorganization Agreement") in complete liquidation of Minnesota Series and
Minnesota Series will thereafter be dissolved as a portfolio of Multi-State
under Massachusetts law. As a result of the Reorganization, each Shareholder
will receive that number of full and fractional Tax-Exempt Shares equal in
value to such Shareholder's pro rata interest in the net assets of Minnesota
Series transferred to Tax-Exempt. Accordingly, as a result of the
Reorganization, each Shareholder of Minnesota Series will become a holder of
Class D shares of Tax-Exempt. Shareholders holding their shares of Minnesota
Series in certificate form will be asked to surrender their certificates in
connection with the Reorganization. Shareholders who do not surrender their
certificates prior to the Closing Date will still receive their shares of
Tax-Exempt; however, such Shareholders will not be able to redeem, transfer or
exchange the Tax-Exempt Shares received until the old certificates have been
surrendered. The Board has determined that the interests of Shareholders will
not be diluted as a result of the Reorganization.

     FOR THE REASONS SET FORTH BELOW UNDER "THE REORGANIZATION -- THE BOARD'S
CONSIDERATION," THE BOARD, INCLUDING THE TRUSTEES WHO ARE NOT "INTERESTED
PERSONS" OF MULTI-STATE, ON BEHALF OF MINNESOTA SERIES ("INDEPENDENT
TRUSTEES"), AS THAT TERM IS DEFINED IN THE INVESTMENT COMPANY ACT OF 1940, AS
AMENDED (THE "1940 ACT"), HAS CONCLUDED THAT THE REORGANIZATION IS IN THE BEST
INTERESTS OF MINNESOTA SERIES AND ITS SHAREHOLDERS AND RECOMMENDS APPROVAL OF
THE REORGANIZATION AGREEMENT.

FEE TABLE

     Minnesota Series and Tax-Exempt each pay expenses for management of their
assets, distribution of their shares and other services, and those expenses are
reflected in the net asset value per share of each fund. Class D shares of
Tax-Exempt do not pay distribution-related fees; however, the other three
Classes offered by Tax-Exempt pay fees for the distribution of their shares.
The following table briefly describes the fees and expenses that a shareholder
of Minnesota Series and a Class D shareholder of Tax-Exempt may pay if they buy
and hold shares of each respective fund. These expenses are deducted from each
respective fund's assets and are based on expenses paid by Minnesota Series for
its fiscal year ended November 30, 1999, and by Class D shares of Tax-Exempt
for its fiscal year ended December 31, 1999. The table also sets forth pro
forma fees for the surviving combined fund (Tax-Exempt) reflecting what the fee
schedule would have been on December 31, 1999, if the Reorganization had been
consummated twelve (12) months prior to that date and assuming Class D fees and
expenses.

Shareholder Fees

<TABLE>
<CAPTION>
                                                                                            PRO FORMA
                                                              MINNESOTA      TAX-EXEMPT      COMBINED
                                                               SERIES         (CLASS D)     (CLASS D)
                                                               ------         ---------     ---------
<S>                                                            <C>              <C>            <C>
MAXIMUM SALES CHARGE (LOAD) IMPOSED ON PURCHASES
 (AS A PERCENTAGE OF OFFERING PRICE)                           4.0%(1)          none           none
MAXIMUM SALES CHARGE (LOAD) IMPOSED ON REINVESTED
 DIVIDENDS                                                      none            none           none
MAXIMUM CONTINGENT DEFERRED SALES CHARGE (LOAD) (AS A
 PERCENTAGE OF THE LESSER OF ORIGINAL PURCHASE PRICE OR
 REDEMPTION PROCEEDS)                                           none            none           none
REDEMPTION FEES                                                 none            none           none
EXCHANGE FEE                                                    none            none           none
</TABLE>


                                       4
<PAGE>

Annual Fund Operating Expenses (expenses that are deducted from fund assets)

<TABLE>
<CAPTION>
                                                                              PRO FORMA
                                             MINNESOTA        TAX-EXEMPT       COMBINED
                                               SERIES          (CLASS D)      (CLASS D)
                                               ------          ---------      ---------
<S>                                             <C>               <C>            <C>
MANAGEMENT FEES                                 0.35%             0.44%          0.44%
DISTRIBUTION AND SERVICE (12B-1) FEES           0.14%(2)          none           none
OTHER EXPENSES                                  0.64%             0.07%          0.07%
TOTAL ANNUAL FUND OPERATING EXPENSES            1.13%             0.51%          0.51%
</TABLE>

- ----------
(1)   Reduced for purchases of $25,000 and over.

(2)   The 12b-1 fee is accrued daily and payable monthly. The entire 12b-1 fee
      payable by Minnesota Series is characterized as a service fee within the
      meaning of National Association of Securities Dealers, Inc. ("NASD")
      guidelines and are payments made for personal service and/or maintenance
      of shareholder accounts.

EXAMPLE

     To attempt to show the effect of these expenses on an investment over
time, the hypotheticals shown below have been created. The Example assumes that
an investor invests $10,000 in either Minnesota Series or Class D shares of
Tax-Exempt or the new combined fund (Tax-Exempt), that the investment has a 5%
return each year and that the operating expenses for each fund remain the same
(as set forth in the chart above). Although a shareholder's actual costs may be
higher or lower, the tables below show a shareholder's costs at the end of each
period based on these assumptions depending upon whether or not a shareholder
sold his shares at the end of each period.

     If a Shareholder SOLD His Shares:

<TABLE>
<CAPTION>
                                           1 YEAR     3 YEARS     5 YEARS     10 YEARS
                                           ------     -------     -------     --------
<S>                                         <C>         <C>         <C>       <C>
Minnesota Series ......................     $511        $746        $997      $1,720
Tax-Exempt (Class D) ..................     $ 52        $164        $285      $  640
Pro Forma Combined (Class D) ..........     $ 52        $164        $285      $  640
</TABLE>

     If a Shareholder HELD His Shares:

<TABLE>
<CAPTION>
                                           1 YEAR     3 YEARS     5 YEARS     10 YEARS
                                           ------     -------     -------     --------
<S>                                         <C>         <C>         <C>       <C>
Minnesota Series ......................     $511        $746        $997      $1,720
Tax-Exempt (Class D) ..................     $ 52        $164        $285      $  640
Pro Forma Combined (Class D) ..........     $ 52        $164        $285      $  640
</TABLE>


                                       5
<PAGE>

     The purpose of the foregoing fee table is to assist the investor or
shareholder in understanding the various costs and expenses that an investor or
shareholder in the fund will bear directly or indirectly. For a more complete
description of these costs and expenses, see "Comparison of Minnesota Series
and Tax-Exempt -- Investment Management and Distribution Plan Fees, Other
Significant Fees, and Purchases, Exchanges and Redemptions" below.

TAX CONSEQUENCES OF THE REORGANIZATION

     As a condition to the Reorganization, Multi-State, on behalf of Minnesota
Series, and Tax-Exempt, will receive an opinion of Mayer, Brown & Platt to the
effect that the Reorganization will constitute a tax-free reorganization for
federal income tax purposes, and that no gain or loss will be recognized by
Minnesota Series or the shareholders of Minnesota Series for federal income tax
purposes as a result of the transactions included in the Reorganization. For
further information about the tax consequences of the Reorganization, see "The
Reorganization -- Tax Aspects of the Reorganization" below.

COMPARISON OF MINNESOTA SERIES AND TAX-EXEMPT

     INVESTMENT OBJECTIVES AND POLICIES. Minnesota Series and Tax-Exempt have
partially similar investment objectives. Both Minnesota Series and Tax-Exempt
seek to provide a high level of current income exempt from federal income tax
consistent with the preservation of capital. However, Minnesota Series also
seeks, as its investment objective, a high level of current income exempt from
Minnesota state income taxes.

     Tax-Exempt seeks to achieve its investment objective by investing at least
80% of its assets in securities that pay interest exempt from federal income
taxes. Minnesota Series seeks to achieve its investment objective by investing
at least 80% of its assets in securities, the interest of which is exempt from
federal and Minnesota state income taxes. Income dividend distributions of
Tax-Exempt, to the extent derived from municipal obligations, are normally
exempt from federal income taxes. Such income dividend distributions, however,
are normally not exempt from Minnesota personal income taxes. Therefore,
shareholders of Minnesota Series who become shareholders of Tax-Exempt
generally will be subject to Minnesota personal income tax on dividend
distributions received on their Tax-Exempt Shares.

     Other than as set forth above, the investment policies of Minnesota Series
and Tax-Exempt are substantially similar; the principal differences between
them are described under "Comparison of Investment Objectives, Policies and
Restrictions" below.

     INVESTMENT MANAGEMENT AND DISTRIBUTION PLAN FEES.  Minnesota Series and
Tax-Exempt obtain management services from MSDW Advisors. With respect to
Minnesota Series, the fund pays MSDW Advisors monthly compensation calculated
daily at an annual rate of 0.35% of the fund's average daily net assets. With
respect to Tax-Exempt, the fund pays MSDW Advisors monthly compensation
calculated daily by applying the following annual rates to the average daily
net assets of the fund: 0.50% of the portion of the daily net assets not
exceeding $500 million; 0.425% of the portion of the daily net assets exceeding
$500 million but not exceeding $750 million; 0.375% of the portion of the daily
net assets exceeding $750 million but not exceeding $1 billion; 0.35% of the
portion of the daily net assets exceeding $1 billion but not exceeding $1.25
billion; and 0.325% of the portion of the daily net assets exceeding $1.25
billion. Each class of shares of Tax-Exempt is subject to the same management
fee rates.

     Multi-State has adopted a distribution plan ("Plan") pursuant to Rule
12b-1 under the 1940 Act whereby each series, including Minnesota Series,
reimburses the Distributor and others for the expenses of certain activities
and services incurred by them in connection with the distribution of each
respective series' shares. Reimbursement for these expenses is made in monthly
payments by, in this case, Minnesota Series, to the

                                       6
<PAGE>

Distributor, which will in no event exceed amounts equal to payment at the
annual rate of 0.15% of the average daily net assets of Minnesota Series. There
are no 12b-1 fees applicable to Tax-Exempt's Class D shares. For further
information relating to the 12b-1 fees applicable to each class of Tax-Exempt
shares, see the section entitled "Share Class Arrangements" in Tax-Exempt's
Prospectus, attached hereto.

     OTHER SIGNIFICANT FEES. Both Minnesota Series and Tax-Exempt pay
additional fees in connection with their operations, including legal, auditing,
transfer agent, trustees fees and custodial fees. See "Synopsis -- Fee Table"
above for the percentage of average net assets represented by such "Other
Expenses."

     PURCHASES, EXCHANGES AND REDEMPTIONS. Shares of Minnesota Series are sold
at net asset value plus an initial sales charge of up to 4.0%. The initial
sales charge is reduced for certain purchases. Shares of Minnesota Series may
be redeemed for cash without redemption or other charge at any time at the net
asset value per share next determined. Class D shares of Tax-Exempt are
currently offered at net asset value and such shares may be redeemed for cash
without redemption or other charge at the net asset value per share next
determined. Normally, Class D shares of Tax-Exempt are offered only to a
limited group of investors. Subsequent to the Reorganization, all Minnesota
Series shares will be designated Class D shares of Tax-Exempt. However,
additional investments (except for reinvestment of distributions received on
shares acquired as a result of the Reorganization) in Class D shares of
Tax-Exempt (or in Class D shares of any other Morgan Stanley Dean Witter Fund)
by Shareholders holding such shares may only be made if those Shareholders are
otherwise eligible to purchase Class D shares. Class D shares acquired in the
Reorganization may, however, be exchanged for Class D shares of another Morgan
Stanley Dean Witter Fund pursuant to Class D's exchange privileges discussed
below.

     Tax-Exempt offers four classes of shares (Class A, Class B, Class C and
Class D) which differ principally in terms of sales charges, distribution and
service fees and ongoing expenses. For further information relating to each of
the classes of Tax-Exempt's shares, see the section entitled "Share Class
Arrangements" in Tax-Exempt's Prospectus.

     Shares of Minnesota Series currently may be exchanged for shares of any
other Multi-State series, for Class A shares of any Morgan Stanley Dean Witter
Fund that offers its shares in more than one class, for shares of Morgan
Stanley Dean Witter Hawaii Municipal Trust, Morgan Stanley Dean Witter
Short-Term U.S. Treasury Trust, Morgan Stanley Dean Witter North American
Government Income Trust, Morgan Stanley Dean Witter Limited Term Municipal
Trust, Morgan Stanley Dean Witter Short-Term Bond Fund and for shares of the
five Morgan Stanley Dean Witter Funds that are money market funds. Class D
shares of Tax-Exempt may be exchanged for Class D shares of any other Morgan
Stanley Dean Witter Fund that offers its shares in more than one class, or any
of Morgan Stanley Dean Witter Short-Term U.S. Treasury Trust, Morgan Stanley
Dean Witter North American Government Income Trust, Morgan Stanley Dean Witter
Limited Term Municipal Trust, Morgan Stanley Dean Witter Short-Term Bond Fund
and the five Morgan Stanley Dean Witter Funds that are money market funds (the
foregoing funds are collectively referred to as the "Exchange Funds"), without
the imposition of an exchange fee.

     Both Minnesota Series and Tax-Exempt provide telephone exchange privileges
to their shareholders. For greater details relating to exchange privileges
applicable to Tax-Exempt, see the section entitled "How to Exchange Shares" in
Tax-Exempt's Prospectus.

     Both Minnesota Series and Tax-Exempt may redeem involuntarily, at net
asset value, most accounts valued at less than $100. However, both funds offer
a reinstatement privilege whereby a shareholder who has not previously
exercised such privilege whose shares have been redeemed or repurchased may,
within thirty-five days after the date of redemption or repurchase, reinstate
any portion or all of the proceeds thereof in shares of the same class from
which such shares were redeemed or repurchased.

                                       7
<PAGE>

     DIVIDENDS. Minnesota Series and Tax-Exempt each declare income dividends
daily and pay dividends from net investment income monthly. Both Minnesota
Series and Tax-Exempt distribute net capital gains, if any, at least annually
in December. Each, however, may determine either to distribute or to retain all
or part of any net long-term capital gains in any year for reinvestment. With
respect to both Minnesota Series and Tax-Exempt, dividends and capital gains
distributions are automatically reinvested in additional shares at net asset
value unless the shareholder elects to receive cash. As discussed above,
Tax-Exempt's income dividend distributions to shareholders are generally exempt
from federal income taxes, whereas Minnesota Series' dividend distributions are
generally exempt from federal and Minnesota state income taxes.

                            PRINCIPAL RISK FACTORS

     The share price or net asset value of Tax-Exempt and Minnesota Series will
fluctuate with changes in the market value of their respective portfolio
securities. The market value of the funds' portfolio securities will increase
or decrease due to a variety of economic, market and political factors,
including changes in prevailing interest rates, which cannot be predicted. The
principal risks of an investment in either Tax-Exempt or Minnesota Series are
the risks associated with their respective fixed-income securities which
primarily consist of municipal obligations. Fixed income securities are subject
to two types of risks: credit risk and interest rate risk.

     Credit risk refers to the possibility that the issuer of a security will
be unable or unwilling to make interest payments and/or repay the principal on
its debt. In the case of certain municipal obligations known as revenue bonds,
the credit risk refers to the possibility that the user fees from a project or
specified revenue source are insufficient to meet interest and/or principal
payment obligations or the credit impairment of the user. Minnesota Series is
subject to the added credit risk of concentrating its investments in a single
state - Minnesota. Because Minnesota Series concentrates its investments in
securities issued by Minnesota state and local governments and government
authorities, Minnesota Series will be significantly affected by the political,
economic and regulatory developments concerning those issuers. Should any
difficulties develop concerning Minnesota issuers' abilities to pay principal
and/or interest on their debt obligations, the value and yield of Minnesota
Series could be adversely affected. Interest rate risk refers to fluctuations
in the value of a fixed-income security resulting from changes in the general
level of interest rates. When the general level of interest rates goes up, the
prices of most fixed-income securities go down. When the general level of
interest rates goes down, the prices of most fixed-income securities go up.

     Unlike Tax-Exempt, Minnesota Series is classified as "non-diversified"
and, as such, its investments are not required to meet certain diversification
requirements under federal law. Compared with "diversified" funds such as
Tax-Exempt, Minnesota Series may invest a greater percentage of its assets in
the securities of an individual issuer. Thus, Minnesota Series' assets may be
concentrated in fewer securities than Tax-Exempt. A decline in the value of
those investments may cause Minnesota Series' overall value to decline to a
greater degree than Tax-Exempt.

     Both Tax-Exempt and Minnesota Series may invest a portion of their
respective assets in inverse floating rate municipal obligations which are
obligations that are typically created through a division of a fixed rate
municipal obligation into two separate instruments, a short-term obligation and
a long-term obligation. The interest rates on inverse floating rate municipal
obligations generally move in the reverse direction of market interest rates.
Inverse floating rate municipal obligations offer the potential for higher
income than is available from fixed rate obligations of comparable maturity and
credit rating but they also carry greater risks. In particular, the prices of
inverse floating rate municipal obligations are more volatile, i.e., they
increase and decrease in response to changes in interest rates to a greater
extent than comparable fixed rate obligations.

                                       8
<PAGE>

     Both Tax-Exempt and Minnesota Series may invest in municipal lease
obligations which are obligations issued by state and local agencies or
authorities to finance equipment and facilities. Certain lease obligations
contain clauses whereby future payments under the lease are dependent upon
annual or periodic legislative appropriations. If these legislative
appropriations do not occur, holders of such municipal lease obligations may
experience difficulty exercising their rights, including disposition of the
property. Both Tax-Exempt and Minnesota Series may also invest in futures
obligations which are considered speculative in nature and involve certain
risks.

     The foregoing discussion is a summary of the principal risk factors. For a
more complete discussion of the risks of each fund, see "Principal Risks" and
"Additional Risk Information" in the Prospectus of Multi-State and in
Tax-Exempt's Prospectus attached hereto and incorporated herein by reference.

                              THE REORGANIZATION

THE PROPOSAL

     The Board of Trustees of Multi-State, on behalf of Minnesota Series,
including the Independent Trustees, having reviewed the financial position of
Minnesota Series and the prospects for achieving economies of scale through the
Reorganization and having determined that the Reorganization is in the best
interests of Minnesota Series and its Shareholders and that the interests of
Shareholders will not be diluted as a result thereof, recommends approval of
the Reorganization by Shareholders of Minnesota Series.

THE BOARD'S CONSIDERATION

     At a meeting held on January 26, 2000, the Board, including all of the
Independent Trustees, unanimously approved the Reorganization Agreement and
determined to recommend that Shareholders approve the Reorganization Agreement.
In reaching this decision, the Board made an extensive inquiry into a number of
factors, particularly the comparative expenses currently incurred in the
operations of Minnesota Series and the Class D shares of Tax-Exempt. The Board
also considered other factors, including, but not limited to: the shrinking
asset base of Minnesota Series which may affect the long-term economic
viability of the fund because of higher costs and disadvantageous economies of
scale (as of December 31, 1999, Minnesota Series had approximately $6.9 million
in net assets compared to Tax-Exempt's $1 billion in net assets); a comparison
of the differences in the investment objectives, policies, restrictions and
portfolios of Minnesota Series and Tax-Exempt particularly, that Tax-Exempt
seeks income exempt from federal income taxes, whereas Minnesota Series seeks
income exempt from both federal and Minnesota state income taxes; the terms and
conditions of the Reorganization which would affect the price of shares to be
issued in the Reorganization; the tax-free nature of the Reorganization; and
any direct or indirect costs to be incurred by Minnesota Series and Tax-Exempt
in connection with the Reorganization.

     In recommending the Reorganization to Shareholders, the Board of
Multi-State, on behalf of Minnesota Series, considered that the Reorganization
would have the following benefits to Shareholders:

     1. Once the Reorganization is consummated, the expenses which would be
borne by Class D shareholders of the "combined fund" are expected to be
significantly lower on a percentage basis than the expenses per share of
Minnesota Series although the investment management fee of Tax-Exempt is higher
than the investment management fee of Minnesota Series. The combined fund's
expenses would be lower in part because Class D shares of Tax-Exempt bear no
12b-1 fees, whereas Minnesota Series pays a 12b-1 fee of up to 0.15% of its
average net assets. Furthermore, the estimated current rate of other expenses
to be paid by Class D of the surviving Tax-Exempt (0.07% of average daily net
assets) would be lower than the rate of other

                                       9
<PAGE>

expenses currently paid by Minnesota Series (0.64% of average daily net
assets). In addition, to the extent that the Reorganization would result in
Shareholders becoming shareholders of a combined larger fund, further economies
of scale could be achieved since various fixed expenses (e.g., auditing and
legal) can be spread over a larger number of shares. The Board noted that the
expense ratio for Minnesota Series was higher (1.13% for its fiscal year ended
November 30, 1999) than the expense ratio for Class D shares of Tax-Exempt
(0.51% for its fiscal year ended December 31, 1999).

     2. Shareholders would have the ability to exchange their Class D shares of
Tax-Exempt acquired as a result of the Reorganization into Class D shares of
any Morgan Stanley Dean Witter Multi-Class Fund. Currently, Shareholders may
only exchange into Class A shares of any Morgan Stanley Dean Witter Multi-Class
Fund. Class D shares bear lower expenses than Class A shares.

     3. The Reorganization is intended to qualify as a tax-free reorganization
for federal income tax purposes, pursuant to which no gain or loss will be
recognized by Minnesota Series or its Shareholders for Federal income tax
purposes as a result of transactions included in the Reorganization.

     The Board of Trustees of Tax-Exempt, including a majority of the
Independent Trustees of Tax-Exempt, also have determined that the
Reorganization is in the best interests of Tax-Exempt and its shareholders and
that the interests of existing shareholders of Tax-Exempt will not be diluted
as a result thereof. The transaction will enable Tax-Exempt to acquire
investment securities which are consistent with Tax-Exempt's investment
objective, without the costs attendant to the purchase of such securities in
the market. Finally, the Board considered that even if the benefits enumerated
above are not realized, the costs to the Fund are sufficiently minor to warrant
taking the opportunity to realize those benefits.

THE REORGANIZATION AGREEMENT

     The terms and conditions under which the Reorganization would be
consummated, as summarized below, are set forth in the Reorganization
Agreement. This summary is qualified in its entirety by reference to the
Reorganization Agreement, a copy of which is attached as Exhibit A to this
Proxy Statement and Prospectus.

     The Reorganization Agreement provides that (i) Minnesota Series will
transfer all of its assets, including portfolio securities, cash (other than
cash amounts retained by Minnesota Series as a "Cash Reserve" in the amount
sufficient to discharge its liabilities not discharged prior to the Valuation
Date (as defined below) and for expenses of the dissolution), cash equivalents
and receivables to Tax-Exempt on the Closing Date in exchange for the
assumption by Tax-Exempt of stated liabilities of Minnesota Series, including
all expenses, costs, charges and reserves, as reflected on an unaudited
statement of assets and liabilities of Minnesota Series prepared by the
Treasurer of Multi-State, on behalf of Minnesota Series, as of the Valuation
Date (as defined below) in accordance with generally accepted accounting
principles consistently applied from the prior audited period, and the delivery
of the Tax-Exempt Shares; (ii) such Tax-Exempt Shares would be distributed to
Shareholders on the Closing Date or as soon as practicable thereafter; (iii)
Minnesota Series would be dissolved; and (iv) the outstanding shares of
Minnesota Series would be canceled.

     The number of Tax-Exempt Shares to be delivered to Minnesota Series will
be determined by dividing the aggregate net asset value of the shares of
Minnesota Series acquired by Tax-Exempt by the net asset value per share of the
Class D shares of Tax-Exempt; these values will be calculated as of the close
of business of the New York Stock Exchange on the third business day following
the receipt of the requisite approval by Shareholders of the Reorganization
Agreement or at such other time as Minnesota Series and Tax-Exempt may agree
(the "Valuation Date"). As an illustration, assume that on the Valuation Date,
the shares of Minnesota Series had an aggregate net asset value (not including
any Cash Reserve of Minnesota Series) of $100,000. If the net asset value per
Class D share of Tax-Exempt were $10 per share at the close of business on the
Valuation Date, the

                                       10
<PAGE>

number of Class D shares of Tax-Exempt to be issued would be 10,000 ($100,000
(divided by)  $10). These 10,000 Class D shares of of Tax-Exempt would be
distributed to the former shareholders of Minnesota Series. This example is
given for illustration purposes only and does not bear any relationship to the
dollar amounts or shares expected to be involved in the Reorganization.

     On the Closing Date or as soon as practicable thereafter, Minnesota Series
will distribute pro rata to its Shareholders of record as of the close of
business on the Valuation Date, the Tax-Exempt Shares it receives. Each
Shareholder will receive Class D shares of Tax-Exempt that corresponds to the
shares of Minnesota Series currently held by that Shareholder. Tax-Exempt will
cause its transfer agent to credit and confirm an appropriate number of
Tax-Exempt Shares to each Shareholder. Certificates for Tax-Exempt Shares will
be issued only upon written request of a Shareholder and only for whole shares,
with fractional shares credited to the name of the Shareholder on the books of
Tax-Exempt. Shareholders who wish to receive certificates representing their
Tax-Exempt Shares must, after receipt of their confirmations, make a written
request to Tax-Exempt's transfer agent Morgan Stanley Dean Witter Trust FSB,
Harborside Financial Center, Jersey City, New Jersey 07311. Shareholders of
Minnesota Series holding their shares in certificate form will be asked to
surrender such certificates in connection with the Reorganization. Shareholders
who do not surrender their certificates prior to the Closing Date will still
receive their shares of Tax-Exempt; however, such Shareholders will not be able
to redeem, transfer or exchange the Tax-Exempt Shares received until the old
certificates have been surrendered.

     The Closing Date will be the next business day following the Valuation
Date. The consummation of the Reorganization is contingent upon the approval of
the Reorganization by the Shareholders and the receipt of the other opinions
and certificates set forth in Sections 6, 7 and 8 of the Reorganization
Agreement and the occurrence of the events described in those Sections, certain
of which may be waived by Minnesota Series or Tax-Exempt. The Reorganization
Agreement may be amended in any mutually agreeable manner. All expenses of this
solicitation, including the cost of preparing and mailing this Proxy Statement
and Prospectus, will be borne, as set forth in this Proxy Statement and
Prospectus under "Expenses of Solicitation," by Minnesota Series and MSDW
Advisors, which expenses are expected to approximate $30,000. Minnesota Series
and Tax-Exempt will bear all of their respective other expenses associated with
the Reorganization.

     The Reorganization Agreement may be terminated and the Reorganization
abandoned at any time, before or after approval by Shareholders or by mutual
consent of Multi-State, on behalf of Minnesota Series, and Tax-Exempt. In
addition, either party may terminate the Reorganization Agreement upon the
occurrence of a material breach of the Reorganization Agreement by the other
party or if, by September 30, 2000, any condition set forth in the
Reorganization Agreement has not been fulfilled or waived by the party entitled
to its benefits.

     Under the Reorganization Agreement, within one year after the Closing
Date, Multi-State, on behalf of Minnesota Series, shall: either pay or make
provision for all of its liabilities and distribute any remaining amount of the
Cash Reserve (after paying or making provision for such liabilities and the
estimated cost of making the distribution) to former Shareholders of Minnesota
Series that received Tax-Exempt Shares. Minnesota Series shall be dissolved as
a portfolio of Multi-State under Massachusetts law promptly following the
distributions of shares of Tax-Exempt to Shareholders of record of Minnesota
Series.

     The effect of the Reorganization is that Shareholders who vote their
shares in favor of the Reorganization Agreement are electing to sell their
shares of Minnesota Series (at net asset value on the Valuation Date calculated
after subtracting any Cash Reserve) and reinvest the proceeds in Tax-Exempt
Shares at net asset value and without recognition of taxable gain or loss for
Federal income tax purposes. See "Tax Aspects of the Reorganization" below. As
noted in "Tax Aspects of the Reorganization" below, if Minnesota Series
recognizes

                                       11
<PAGE>

net gain from the sale of securities prior to the Closing Date, such gain, to
the extent not offset by capital loss carryforwards, will be distributed to
Shareholders prior to the Closing Date and will be taxable to Shareholders as
capital gain.

     Shareholders will continue to be able to redeem their shares of Minnesota
Series at net asset value next determined after receipt of the redemption
request until the close of business on the business day next preceding the
Closing Date. Redemption requests received by Multi-State, on behalf of
Minnesota Series, thereafter will be treated as requests for redemption of
shares of Tax-Exempt.

TAX ASPECTS OF THE REORGANIZATION

     At least one but not more than 20 business days prior to the Valuation
Date, Minnesota Series will declare and pay a dividend or dividends which,
together with all previous such dividends, will have the effect of distributing
to Shareholders all of Minnesota Series' investment company taxable income for
all periods since the inception of Minnesota Series through and including the
Valuation Date (computed without regard to any dividends paid deduction), and
all of Minnesota Series' net capital gain, if any, realized in such periods
(after reduction for any capital loss carryforward).

     The Reorganization is intended to qualify for Federal income tax purposes
as a tax-free reorganization under Section 368(a)(1)(C) of the Internal Revenue
Code of 1986, as amended (the "Code").

     As a condition to the Reorganization, Multi-State, on behalf of Minnesota
Series, and Tax-Exempt will receive an opinion of Mayer, Brown & Platt to the
effect that, based on certain assumptions, facts, the terms of the
Reorganization Agreement and representations set forth in the Reorganization
Agreement or otherwise provided by Multi-State, on behalf of Minnesota Series,
and Tax-Exempt (including a representation to the effect that Tax-Exempt has no
plan or intention to sell or otherwise dispose of more than fifty percent of
the assets of Minnesota Series acquired in the Reorganization except for
dispositions made in the ordinary course of business):

     1. The transfer of Minnesota Series' assets in exchange for the Tax-Exempt
Shares and the assumption by Tax-Exempt of certain stated liabilities of
Minnesota Series followed by the distribution by Minnesota Series of the
Tax-Exempt Shares to Shareholders in exchange for their Minnesota Series shares
pursuant to and in accordance with the terms of the Reorganization Agreement
will constitute a "reorganization" within the meaning of Section 368(a)(1)(C)
of the Code, and Minnesota Series and Tax-Exempt will each be a "party to a
reorganization" within the meaning of Section 368(b) of the Code;

     2. No gain or loss will be recognized by Tax-Exempt upon the receipt of
the assets of Minnesota Series solely in exchange for the Tax-Exempt Shares and
the assumption by Tax-Exempt of the stated liabilities of Minnesota Series;

     3. No gain or loss will be recognized by Minnesota Series upon the
transfer of the assets of Minnesota Series to Tax-Exempt in exchange for the
Tax-Exempt Shares and the assumption by Tax-Exempt of the stated liabilities or
upon the distribution of Tax-Exempt Shares to Shareholders in exchange for
their Minnesota Series shares;

     4. No gain or loss will be recognized by Shareholders upon the exchange of
the shares of Minnesota Series for the Tax-Exempt Shares;

     5. The aggregate tax basis for the Tax-Exempt Shares received by each of
the Shareholders pursuant to the Reorganization will be the same as the
aggregate tax basis of the shares in Minnesota Series held by each such
Shareholder immediately prior to the Reorganization;

                                       12
<PAGE>

     6. The holding period of the Tax-Exempt Shares to be received by each
Shareholder will include the period during which the shares in Minnesota Series
surrendered in exchange therefor were held (provided such shares in Minnesota
Series were held as capital assets on the date of the Reorganization);

     7. The tax basis of the assets of Minnesota Series acquired by Tax-Exempt
will be the same as the tax basis of such assets of Minnesota Series
immediately prior to the Reorganization; and

     8. The holding period of the assets of Minnesota Series in the hands of
Tax-Exempt will include the period during which those assets were held by
Minnesota Series.

     SHAREHOLDERS SHOULD CONSULT THEIR TAX ADVISORS REGARDING THE EFFECT, IF
ANY, OF THE PROPOSED TRANSACTION IN LIGHT OF THEIR INDIVIDUAL CIRCUMSTANCES.
BECAUSE THE FOREGOING DISCUSSION ONLY RELATES TO THE FEDERAL INCOME TAX
CONSEQUENCES OF THE PROPOSED TRANSACTION, SHAREHOLDERS SHOULD ALSO CONSULT
THEIR TAX ADVISORS AS TO STATE AND LOCAL TAX CONSEQUENCES, IF ANY, OF THE
PROPOSED TRANSACTION.

DESCRIPTION OF SHARES

     Class D shares of Tax-Exempt to be issued pursuant to the Reorganization
Agreement will, when issued, be fully paid and non-assessable by Tax-Exempt and
transferable without restrictions and will have no preemptive rights. As stated
above, Class D shares of Tax-Exempt are not subject to any sales charge on
purchase or redemption or any 12b-1 fee.

CAPITALIZATION TABLE (UNAUDITED)

     The following table sets forth the capitalization of Tax-Exempt and
Minnesota Series as of January 31, 2000 and on a pro forma combined basis as if
the Reorganization had occurred on that date:

<TABLE>
<CAPTION>
                                                                                                NET ASSET
                                                                                   SHARES         VALUE
                                                               NET ASSETS       OUTSTANDING     PER SHARE
                                                               ----------       -----------     ---------
<S>                                                        <C>                 <C>             <C>
Minnesota Series .......................................    $    6,829,578         694,583      $  9.83
Tax-Exempt:
 (Class A) .............................................    $   17,997,261       1,638,873      $ 10.98
 (Class B) .............................................    $  137,547,537      12,473,473      $ 11.03
 (Class C) .............................................    $    9,761,306         887,027      $ 11.00
 (Class D) .............................................    $  834,614,583      76,058,734      $ 10.97
Total Tax-Exempt (Class A -- D) ........................    $  999,920,687              --           --
Combined Fund (pro forma) (Tax-Exempt after the
 Reorganization)
 (Class A) .............................................    $   17,997,261       1,638,873      $ 10.98
 (Class B) .............................................    $  137,547,537      12,473,473      $ 11.03
 (Class C) .............................................    $    9,761,306         887,027      $ 11.00
 (Class D) .............................................    $  841,444,161      76,681,303      $ 10.97
Total Combined Fund (pro forma) (Class A -- D) .........    $1,006,750,265              --           --
</TABLE>

APPRAISAL RIGHTS

     Shareholders will have no appraisal rights in connection with the
Reorganization.

        COMPARISON OF INVESTMENT OBJECTIVES, POLICIES AND RESTRICTIONS

INVESTMENT OBJECTIVES AND POLICIES

     Minnesota Series and Tax-Exempt have partially similar investment
objectives. Minnesota Series seeks to provide a high level of current income
exempt from both federal and Minnesota state income taxes, consistent with
preservation of capital. Tax-Exempt seeks to provide a high level of current
income exempt from federal income tax consistent with preservation of capital.


                                       13
<PAGE>

     Both Minnesota Series and Tax-Exempt invest at least 80% of their
respective assets in securities that pay interest exempt from federal income
taxes, and with respect to Minnesota Series, Minnesota state income taxes, in
accordance with their respective investment objectives set forth above.
Tax-Exempt invests at least 75% of its assets in (i) municipal bonds rated
within the three highest grades by either Moody's Investors Service
("Moody's"), Standard & Poor's Corporation ("S&P") or Fitch IBCA, Inc.
("Fitch"); (ii) municipal notes rated within the two highest grades by Moody's,
S&P or Fitch, or, if not rated, have outstanding bonds within the three highest
grades by Moody's, S&P or Fitch; and (iii) municipal commercial paper rated
within the highest grade by such organizations. By contrast, Minnesota Series
may invest any amount of its assets in municipal bonds rated within the four
highest rating categories, and in municipal notes rated within the two highest
rating categories but, if unrated, they must have bonds outstanding rated
within the four highest categories. Like Tax-Exempt, Minnesota Series may
invest without limitation in municipal notes rated within the highest rating
category. In addition, Tax-Exempt is permitted to invest up to 5% of its assets
in municipal obligations rated below investment grade, commonly known as "junk
bonds," whereas, Minnesota Series may not invest in municipal obligations rated
below investment grade. Unrated securities may only be purchased by either
Minnesota Series or Tax-Exempt if such securities are judged by the Investment
Manager to be of comparable quality to the rated securities described above.

     Both Minnesota Series and Tax-Exempt may invest up to 10% of their
respective assets in inverse floating rate municipal obligations. The interest
rates on these obligations generally move in the reverse direction of market
interest rates. If market interest rates fall, the interest rates on the
obligations will increase and if market interest rates increase, the interest
rates on the obligations will fall.

     Both Minnesota Series and Tax-Exempt may invest up to 20% of their
respective assets in taxable money market instruments. Minnesota Series may
invest up to 20% of its assets in tax-exempt securities of other states and
municipalities. (Tax-Exempt may invest any amount of its assets in municipal
obligations of any state.)

     Minnesota Series may invest any amount of its assets in securities that
pay interest subject to the "alternative minimum tax" ("AMT") with the result
that some taxpayers may have to pay tax on income distributions from the
Minnesota Series. Tax-Exempt may only invest up to 20% of its assets in
securities subject to the AMT unless the fund has adopted a temporary defensive
posture as set forth below.

     Both Minnesota Series and Tax-Exempt may take temporary "defensive"
positions that are inconsistent with each fund's principal investment
strategies in attempting to respond to adverse market conditions. In doing so,
Minnesota Series may invest any amount of its assets in taxable money market
securities or, in the highest grade municipal obligations issued by states
other than Minnesota where interest on such obligations would normally be
exempt from federal income tax but not from Minnesota income tax. In addition,
during such a defensive posture, Tax-Exempt may also invest any amount of its
assets in taxable securities, or in tax-exempt securities subject to the AMT.

     Both Minnesota Series and Tax-Exempt may (i) purchase securities on a
when-issued or delayed delivery basis, (ii) purchase or sell securities on a
forward commitment basis, (iii) purchase variable and floating rate municipal
obligations, (iv) enter into repurchase agreements subject to certain
procedures designed to minimize risks associated with such agreements, (v)
purchase industrial revenue bonds, including lease obligations, and private
activity bonds, (vi) invest in zero coupon securities, (vii) lend their
portfolio securities and (viii) enter into options and futures transactions.
Additionally, Tax-Exempt may purchase securities on a when, as and if issued
basis.

     The foregoing discussion is a summary of the principal differences and
similarities between the investment policies of the funds. For a more complete
discussion of each fund's policies, see "Principal Investment Strategies" and
"Additional Investment Strategy Information" in Tax-Exempt's Prospectus and
"Principal

                                       14
<PAGE>

Investment Strategy" and "Additional Investment Strategy Information" in
Multi-State's Prospectus; and "Description of the Fund and Its Investments and
Risks" in Tax-Exempt's Statement of Additional Information and "Description of
the Fund and the Investments and Risks of the Series" in Multi-State's
Statement of Additional Information.

INVESTMENT RESTRICTIONS

     The investment restrictions adopted by Minnesota Series and Tax-Exempt as
fundamental policies are substantially similar and are summarized under the
caption "Description of the Fund and Its Investments and Risks -- Fund
Policies/Investment Restrictions" in their respective Statements of Additional
Information. A fundamental investment restriction cannot be changed without the
vote of the majority of the outstanding voting securities of a fund, as defined
in the 1940 Act. The material differences are as follows: (a) Tax-Exempt may
not invest more than 5% of the value of its total assets in the securities of
any one issuer (other than U.S. Government securities); Minnesota Series,
because it is a non-diversified fund, has no such investment restriction but
limits its investments of 5% or more in the securities of any one issuer as to
50% of its total assets in order to qualify as a regulated investment company
under Subchapter M of the Code; (b) Tax-Exempt may not purchase more than 10%
of all outstanding taxable debt securities of any one issuer (other than
obligations issued or guaranteed by the U.S. Government or its agencies or
instrumentalities); Minnesota Series has no such investment restriction; and
(c) Tax-Exempt may not invest more than 5% of the value of its total assets in
taxable securities of issuers (other than U.S. Government securities) that have
a record, together with predecessors, of less than three years of continuous
operation; Minnesota Series has no such investment restriction.

                 ADDITIONAL INFORMATION ABOUT MINNESOTA SERIES
                                AND TAX-EXEMPT

GENERAL

     For a discussion of the organization and operation of Tax-Exempt and
Minnesota Series, see "Fund Management" and "Investment Objective" in their
respective Prospectuses.

FINANCIAL INFORMATION

     For certain financial information about Tax-Exempt and Minnesota Series,
see "Financial Highlights" and "Past Performance" in their respective
Prospectuses.

MANAGEMENT

     For information about the respective Board of Trustees, Investment
Manager, and the Distributor of Tax-Exempt and Minnesota Series, see "Fund
Management" in their respective Prospectuses.

DESCRIPTION OF SECURITIES AND SHAREHOLDER INQUIRIES

     For a description of the nature and most significant attributes of shares
of Minnesota Series and Tax-Exempt, and information regarding shareholder
inquiries, see "Capital Stock and Other Securities" in their respective
Statements of Additional Information.

DIVIDENDS, DISTRIBUTIONS AND TAXES

     For a discussion of Tax-Exempt's and Minnesota Series' policies with
respect to dividends, distributions and taxes, see "Distributions" and "Tax
Consequences" in their respective Prospectuses as well as the discussion herein
under "Synopsis -- Purchases, Exchanges and Redemptions."

                                       15
<PAGE>

PURCHASES, REPURCHASES AND REDEMPTIONS

     For a discussion of how Tax-Exempt's and Minnesota Series' shares may be
purchased, repurchased and redeemed, see "How to Buy Shares," "How to Exchange
Shares" and "How to Sell Shares" in their respective Prospectuses.

                  MANAGEMENT'S DISCUSSION OF FUND PERFORMANCE

     For a discussion of Tax-Exempt's performance, see management's letter to
shareholders in its Annual Report for its fiscal year ended December 31, 1999
accompanying this Proxy Statement and Prospectus. For a discussion of the
performance of Minnesota Series, see Multi-State's Annual Report for its fiscal
year ended November 30, 1999.

                       FINANCIAL STATEMENTS AND EXPERTS

     The financial statements of Tax-Exempt, for the year ended December 31,
1999, and Minnesota Series, for the year ended November 30, 1999 that are
incorporated by reference in the Statement of Additional Information relating
to the Registration Statement on Form N-14 of which this Proxy Statement and
Prospectus forms a part, have been audited by PricewaterhouseCoopers LLP,
independent accountants. The financial statements have been incorporated by
reference in reliance upon such reports given upon the authority of
PricewaterhouseCoopers LLP as experts in accounting and auditing.

                                 LEGAL MATTERS

     Certain legal matters concerning the issuance of shares of Tax-Exempt will
be passed upon by Mayer, Brown & Platt, New York, New York. Such firm will rely
on Massachusetts counsel as to matters of Massachusetts law.

                             AVAILABLE INFORMATION

     Additional information about Minnesota Series and Tax-Exempt is available,
as applicable, in the following documents which are incorporated herein by
reference: (i) Tax-Exempt's Prospectus dated February 24, 2000, attached to
this Proxy Statement and Prospectus, which Prospectus forms a part of
Post-Effective Amendment No. 23 to Tax-Exempt's Registration Statement on Form
N-1A (File Nos. 2-66268; 811-2979); (ii) Tax-Exempt's Annual Report for its
fiscal year ended December 31, 1999, accompanying this Proxy Statement and
Prospectus; (iii) Multi-State's Prospectus dated February 25, 2000, which
Prospectus forms a part of Post-Effective Amendment No. 12 to Multi-State's
Registration Statement on Form N-1A (File Nos. 33-37562; 811-6208); and (iv)
Multi-State's Annual Report for its fiscal year ended November 30, 1999. The
foregoing documents may be obtained without charge by calling (800) 869-NEWS
(toll-free).

     Minnesota Series and Tax-Exempt are subject to the informational
requirements of the Securities Exchange Act of 1934, as amended, and in
accordance therewith, file reports and other information with the Commission.
Proxy material, reports and other information about Minnesota Series and
Tax-Exempt which are of public record can be inspected and copied at public
reference facilities maintained by the Commission at Room 1204, Judiciary
Plaza, 450 Fifth Street, NW, Washington, D.C. 20549 and certain of its regional
offices, and copies of such materials can be obtained at prescribed rates from
the Public Reference Branch, Office of Consumer Affairs and Information
Services, Securities and Exchange Commission, Washington, D.C. 20549.

                                       16
<PAGE>

                                OTHER BUSINESS

     Management of Minnesota Series knows of no business other than the matters
specified above which will be presented at the Meeting. Since matters not known
at the time of the solicitation may come before the Meeting, the proxy as
solicited confers discretionary authority with respect to such matters as
properly come before the Meeting, including any adjournment or adjournments
thereof, and it is the intention of the persons named as attorneys-in-fact in
the proxy to vote this proxy in accordance with their judgment on such matters.

                                      By Order of the Board of Trustees


                                      Barry Fink,
                                      Secretary

April 7, 2000

                                       17
<PAGE>

                                                                      EXHIBIT A

                     AGREEMENT AND PLAN OF REORGANIZATION

     THIS AGREEMENT AND PLAN OF REORGANIZATION ("Agreement") is made as of this
26th day of January, 2000, by and between MORGAN STANLEY DEAN WITTER TAX-EXEMPT
SECURITIES TRUST, a Massachusetts business trust ("Tax-Exempt") and MORGAN
STANLEY DEAN WITTER MULTI-STATE MUNICIPAL SERIES TRUST, a Massachusetts
business trust ("Multi-State"), on behalf of its series, MINNESOTA SERIES
("Minnesota Series"). (Where appropriate, references to Minnesota Series mean
Multi-State, on behalf of Minnesota Series.)

     This Agreement is intended to be and is adopted as a "plan of
reorganization" within the meaning of Treas. Reg. 1.368-2(g), for a
reorganization under Section 368(a)(1) of the Internal Revenue Code of 1986, as
amended (the "Code"). The reorganization ("Reorganization") will consist of the
transfer to Tax-Exempt of substantially all of the assets of Minnesota Series
in exchange for the assumption by Tax-Exempt of all stated liabilities of
Minnesota Series and the issuance by Tax-Exempt of Class D shares of beneficial
interest, par value $0.01 per share (the "Tax-Exempt Shares"), to be
distributed, after the Closing Date hereinafter referred to, to the
shareholders of Minnesota Series in liquidation of Minnesota Series as provided
herein, all upon the terms and conditions hereinafter set forth in this
Agreement.

     In consideration of the premises and of the covenants and agreements
hereinafter set forth, the parties hereto covenant and agree as follows:

1. THE REORGANIZATION AND LIQUIDATION OF MINNESOTA SERIES

     1.1 Subject to the terms and conditions herein set forth and on the basis
of the representations and warranties contained herein, Minnesota Series agrees
to assign, deliver and otherwise transfer the Minnesota Series Assets (as
defined in paragraph 1.2) to Tax-Exempt and Tax-Exempt agrees in exchange
therefor to assume all of Minnesota Series stated liabilities on the Closing
Date as set forth in paragraph 1.3(a) and to deliver to Minnesota Series the
number of Tax-Exempt Shares, including fractional Tax-Exempt Shares, determined
in the manner set forth in paragraph 2.3. Such transactions shall take place at
the closing provided for in paragraph 3.1 ("Closing").

     1.2 (a) The "Minnesota Series Assets" shall consist of all property,
including without limitation, all cash (other than the "Cash Reserve" (as
defined in paragraph 1.3(b)), cash equivalents, securities and dividend and
interest receivables owned by Minnesota Series, and any deferred or prepaid
expenses shown as an asset on Minnesota Series' books on the Valuation Date.

     (b) On or prior to the Valuation Date, Multi-State will provide Tax-Exempt
with a list of all of Minnesota Series assets to be assigned, delivered and
otherwise transferred to Tax-Exempt and of the stated liabilities to be assumed
by Tax-Exempt pursuant to this Agreement. Minnesota Series reserves the right
to sell any of the securities on such list but will not, without the prior
approval of Tax-Exempt, acquire any additional securities other than securities
of the type in which Tax-Exempt is permitted to invest and in amounts agreed to
in writing by Tax-Exempt. Tax-Exempt will, within a reasonable time prior to
the Valuation Date, furnish Minnesota Series with a statement of Tax-Exempt's
investment objectives, policies and restrictions and a list of the securities,
if any, on the list referred to in the first sentence of this paragraph that do
not conform to Tax-Exempt's investment objective, policies and restrictions. In
the event that Minnesota Series holds any investments that Tax-Exempt is not
permitted to hold, Minnesota Series will dispose of such securities on or prior
to the Valuation Date. In addition, if it is determined that the portfolios of
Minnesota Series and Tax-Exempt, when aggregated, would contain investments
exceeding certain percentage limitations imposed

                                      A-1
<PAGE>

upon Tax-Exempt with respect to such investments, Minnesota Series if requested
by Tax-Exempt will, on or prior to the Valuation Date, dispose of and/or
reinvest a sufficient amount of such investments as may be necessary to avoid
violating such limitations as of the Closing Date (as defined in paragraph
3.1).

     1.3 (a) Minnesota Series will endeavor to discharge all of its liabilities
and obligations on or prior to the Valuation Date. Tax-Exempt will assume all
stated liabilities, which includes, without limitation, all expenses, costs,
charges and reserves reflected on an unaudited Statement of Assets and
Liabilities of Minnesota Series prepared by the Treasurer of Multi-State, on
behalf of Minnesota Series, as of the Valuation Date in accordance with
generally accepted accounting principles consistently applied from the prior
audited period.

     (b) On the Valuation Date, Minnesota Series may establish a cash reserve,
which shall not exceed 5% of Minnesota Series' net assets as of the close of
business on the Valuation Date ("Cash Reserve") to be retained by Minnesota
Series and used for the payment of its liabilities not discharged prior to the
Valuation Date and for the expenses of dissolution.

     1.4 In order for Minnesota Series to comply with Section 852(a)(1) of the
Code and to avoid having any investment company taxable income or net capital
gain (as defined in Sections 852(b)(2) and 1222(11) of the Code, respectively)
in the short taxable year ending with its dissolution, Minnesota Series will on
or before the Valuation Date (a) declare a dividend in an amount large enough
so that it will have declared dividends of all of its investment company
taxable income and net capital gain, if any, for such taxable year (determined
without regard to any deduction for dividends paid) and (b) distribute such
dividend.

     1.5 On the Closing Date or as soon as practicable thereafter, Minnesota
Series will distribute Tax-Exempt Shares received by Minnesota Series pursuant
to paragraph 1.1 pro rata to its shareholders of record determined as of the
close of business on the Valuation Date ("Minnesota Series Shareholders"). Each
Minnesota Series Shareholder will receive Class D shares of Tax-Exempt. Such
distribution will be accomplished by an instruction, signed by the Secretary of
Multi-State, to transfer Tax-Exempt Shares then credited to Minnesota Series'
account on the books of Tax-Exempt to open accounts on the books of Tax-Exempt
in the names of the Minnesota Series Shareholders and representing the
respective pro rata number of Tax-Exempt Shares due such Minnesota Series
Shareholders. All issued and outstanding shares of Minnesota Series
simultaneously will be canceled on Minnesota Series' books; however, share
certificates representing interests in Minnesota Series will represent a number
of Tax-Exempt Shares after the Closing Date as determined in accordance with
paragraph 2.3. Tax-Exempt will issue certificates representing Tax-Exempt
Shares in connection with such exchange only upon the written request of a
Minnesota Series Shareholder.

     1.6 Ownership of Tax-Exempt Shares will be shown on the books of
Tax-Exempt's transfer agent. Tax-Exempt Shares will be issued in the manner
described in Tax-Exempt's current Prospectus and Statement of Additional
Information.

     1.7 Any transfer taxes payable upon issuance of Tax-Exempt Shares in a
name other than the registered holder of Tax-Exempt Shares on Minnesota Series'
books as of the close of business on the Valuation Date shall, as a condition
of such issuance and transfer, be paid by the person to whom Tax-Exempt Shares
are to be issued and transferred.

     1.8 Any reporting responsibility of Multi-State, on behalf of Minnesota
Series, is and shall remain the responsibility of Multi-State up to and
including the date on which Minnesota Series is dissolved pursuant to paragraph
1.9.

     1.9 Within one year after the Closing Date, Minnesota Series shall pay or
make provision for the payment of all its liabilities and taxes, and distribute
to the shareholders of Minnesota Series as of the close of business on the
Valuation Date any remaining amount of the Cash Reserve (as reduced by the
estimated cost of

                                      A-2
<PAGE>

distributing it to shareholders). If and to the extent that any trust, escrow
account, or other similar entity continues after the close of such one-year
period in connection either with making provision for payment of liabilities or
taxes or with distributions to shareholders of Minnesota Series, such entity
shall either (i) qualify as a liquidating trust under Section 7701 of the Code
(and applicable Treasury Regulations thereunder) or other entity which does not
constitute a continuation of Minnesota Series for federal income tax purposes,
or (ii) be subject to a waiver under Section 368(a)(2)(G)(ii) of the complete
distribution requirement of Section 368(a)(2)(G)(i) of the Code. Minnesota
Series shall be dissolved as a portfolio of Multi-State under Minnesota law,
promptly following the making of all distributions pursuant to paragraph 1.5
(and, in any event, within one year after the Closing Date).

     1.10 Copies of all books and records maintained on behalf of Minnesota
Series in connection with its obligations under the Investment Company Act of
1940, as amended (the "1940 Act"), the Code, state blue sky laws or otherwise
in connection with this Agreement will promptly after the Closing be delivered
to officers of Tax-Exempt or their designee and Tax-Exempt or its designee
shall comply with applicable record retention requirements to which Minnesota
Series is subject under the 1940 Act.

2. VALUATION

     2.1 The value of the Minnesota Series Assets shall be the value of such
assets computed as of 4:00 p.m. on the New York Stock Exchange on the third
business day following the receipt of the requisite approval by shareholders of
Minnesota Series of this Agreement or at such time on such earlier or later
date after such approval as may be mutually agreed upon in writing (such time
and date being hereinafter called the "Valuation Date"), using the valuation
procedures set forth in Tax-Exempt's then current Prospectus and Statement of
Additional Information.

     2.2 The net asset value of a Tax-Exempt Share shall be the net asset value
per share computed on the Valuation Date, using the valuation procedures set
forth in Tax-Exempt's then current Prospectus and Statement of Additional
Information.

     2.3 The number of Tax-Exempt Shares (including fractional shares, if any)
to be issued hereunder shall be determined, with respect to each class, by
dividing the aggregate net asset value of each class of Minnesota Series shares
(determined in accordance with paragraph 2.1) by the net asset value per share
of Class D shares of Tax-Exempt (determined in accordance with paragraph 2.2).
For purposes of this paragraph, the aggregate net asset value of the shares of
Minnesota Series shall not include the amount of the Cash Reserve.

     2.4 All computations of value shall be made by Morgan Stanley Dean Witter
Services Company Inc. ("MSDW Services") in accordance with its regular practice
in pricing Tax-Exempt. Tax-Exempt shall cause MSDW Services to deliver a copy
of its valuation report at the Closing.

3. CLOSING AND CLOSING DATE

     3.1 The Closing shall take place on the next business day following the
Valuation Date (the "Closing Date"). The Closing shall be held as of 9:00 a.m.
Eastern time, or at such other time as the parties may agree. The Closing shall
be held in a location mutually agreeable to the parties hereto. All acts taking
place at the Closing shall be deemed to take place simultaneously as of 9:00
a.m. Eastern time on the Closing Date unless otherwise provided.

     3.2 Portfolio securities held by Minnesota Series and represented by a
certificate or other written instrument shall be presented by it or on its
behalf to The Bank of New York (the "Custodian"), as custodian for Tax-Exempt,
for examination no later than five business days preceding the Valuation Date.
Such portfolio

                                      A-3
<PAGE>

securities (together with any cash or other assets) shall be delivered by
Minnesota Series to the Custodian for the account of Tax-Exempt on or before
the Closing Date in conformity with applicable custody provisions under the
1940 Act and duly endorsed in proper form for transfer in such condition as to
constitute good delivery thereof in accordance with the custom of brokers. The
portfolio securities shall be accompanied by all necessary Federal and state
stock transfer stamps or a check for the appropriate purchase price of such
stamps. Portfolio securities and instruments deposited with a securities
depository (as defined in Rule 17f-4 under the 1940 Act) shall be delivered on
or before the Closing Date by book-entry in accordance with customary practices
of such depository and the Custodian. The cash delivered shall be in the form
of a Federal Funds wire, payable to the order of "The Bank of New York,
Custodian for Morgan Stanley Dean Witter Tax-Exempt Securities Trust."

     3.3 In the event that on the Valuation Date, (a) the New York Stock
Exchange shall be closed to trading or trading thereon shall be restricted or
(b) trading or the reporting of trading on such Exchange or elsewhere shall be
disrupted so that, in the judgment of both Tax-Exempt and Minnesota Series,
accurate appraisal of the value of the net assets of Tax-Exempt or the
Minnesota Series Assets is impracticable, the Valuation Date shall be postponed
until the first business day after the day when trading shall have been fully
resumed without restriction or disruption and reporting shall have been
restored.

     3.4 If requested, Multi-State shall deliver to Tax-Exempt or its designee
(a) at the Closing, a list, certified by its Secretary, of the names, addresses
and taxpayer identification numbers of the Minnesota Series Shareholders and
the number and percentage ownership of outstanding Minnesota Series shares
owned by each such Minnesota Series Shareholder, all as of the Valuation Date,
and (b) as soon as practicable after the Closing, all original documentation
(including Internal Revenue Service forms, certificates, certifications and
correspondence) relating to the Minnesota Series Shareholders' taxpayer
identification numbers and their liability for or exemption from back-up
withholding. Tax-Exempt shall issue and deliver to such Secretary a
confirmation evidencing delivery of Tax-Exempt Shares to be credited on the
Closing Date to Minnesota Series or provide evidence satisfactory to Minnesota
Series that such Tax-Exempt Shares have been credited to Minnesota Series'
account on the books of Tax-Exempt. At the Closing, each party shall deliver to
the other such bills of sale, checks, assignments, share certificates, if any,
receipts or other documents as such other party or its counsel may reasonably
request.

4. COVENANTS OF TAX-EXEMPT AND MINNESOTA SERIES

     4.1 Except as otherwise expressly provided herein with respect to
Minnesota Series, Tax-Exempt and Minnesota Series each will operate its
business in the ordinary course between the date hereof and the Closing Date,
it being understood that such ordinary course of business will include
customary dividends and other distributions.

     4.2 Tax-Exempt will prepare and file with the Securities and Exchange
Commission ("Commission") a registration statement on Form N-14 under the
Securities Act of 1933, as amended ("1933 Act"), relating to Tax-Exempt Shares
("Registration Statement"). Multi-State will provide Tax-Exempt with the Proxy
Materials as described in paragraph 4.3 below, for inclusion in the
Registration Statement. Multi-State will further provide Tax-Exempt with such
other information and documents relating to Minnesota Series as are reasonably
necessary for the preparation of the Registration Statement.

     4.3 Multi-State will call a meeting of the Minnesota Series shareholders
to consider and act upon this Agreement and to take all other action necessary
to obtain approval of the transactions contemplated herein. Multi-State will
prepare the notice of meeting, form of proxy and proxy statement (collectively,
"Proxy

                                      A-4
<PAGE>

Materials") to be used in connection with such meeting; provided that
Tax-Exempt will furnish Multi-State with its currently effective prospectus for
inclusion in the Proxy Materials and with such other information relating to
Tax-Exempt as is reasonably necessary for the preparation of the Proxy
Materials.

     4.4 Multi-State will assist Tax-Exempt in obtaining such information as
Tax-Exempt reasonably requests concerning the beneficial ownership of Minnesota
Series shares.

     4.5 Subject to the provisions of this Agreement, Tax-Exempt and
Multi-State will each take, or cause to be taken, all action, and do or cause
to be done, all things reasonably necessary, proper or advisable to consummate
and make effective the transactions contemplated by this Agreement.

     4.6 Multi-State shall furnish or cause to be furnished to Tax-Exempt
within 30 days after the Closing Date a statement of Minnesota Series' assets
and liabilities as of the Closing Date, which statement shall be certified by
Multi-State's Treasurer and shall be in accordance with generally accepted
accounting principles consistently applied. As promptly as practicable, but in
any case within 60 days after the Closing Date, Minnesota Series shall furnish
Tax-Exempt, in such form as is reasonably satisfactory to Tax-Exempt, a
statement certified by Multi-State's Treasurer of earnings and profits of
Minnesota Series for Federal income tax purposes that will be carried over to
Tax-Exempt pursuant to Section 381 of the Code.

     4.7 As soon after the Closing Date as is reasonably practicable,
Multi-State (a) shall prepare and file all Federal and other tax returns and
reports of Minnesota Series required by law to be filed with respect to all
periods ending on or before the Closing Date but not theretofore filed and (b)
shall pay all Federal and other taxes shown as due thereon and/or all Federal
and other taxes that were unpaid as of the Closing Date, including without
limitation, all taxes for which the provision for payment was made as of the
Closing Date (as represented in paragraph 5.2(k)).

     4.8 Tax-Exempt agrees to use all reasonable efforts to obtain the
approvals and authorizations required by the 1933 Act and the 1940 Act and to
make such filings required by the state Blue Sky and securities laws as it may
deem appropriate in order to continue its operations after the Closing Date.

5. REPRESENTATIONS AND WARRANTIES

     5.1 Tax-Exempt represents and warrants to Multi-State, on behalf of
Minnesota Series, as follows:

          (a) Tax-Exempt is a validly existing Massachusetts business trust with
     full power to carry on its business as presently conducted;

          (b) Tax-Exempt is a duly registered, open-end, management investment
     company, and its registration with the Commission as an investment company
     under the 1940 Act and the registration of its shares under the 1933 Act
     are in full force and effect;

          (c) All of the issued and outstanding shares of Tax-Exempt have been
     offered and sold in compliance in all material respects with applicable
     registration requirements of the 1933 Act and state securities laws. Shares
     of Tax-Exempt are registered in all jurisdictions in which they are
     required to be registered under state securities laws and other laws, and
     said registrations, including any periodic reports or supplemental filings,
     are complete and current, all fees required to be paid have been paid, and
     Tax-Exempt is not subject to any stop order and is fully qualified to sell
     its shares in each state in which its shares have been registered;

          (d) The current Prospectus and Statement of Additional Information of
     Tax-Exempt conform in all material respects to the applicable requirements
     of the 1933 Act and the 1940 Act and the regulations thereunder and do not
     include any untrue statement of a material fact or omit to state any
     material fact required to be stated therein or necessary to make the
     statements therein, in light of the circumstances under which they were
     made, not misleading;

                                      A-5
<PAGE>

          (e) Tax-Exempt is not in, and the execution, delivery and performance
     of this Agreement will not result in a, material violation of any provision
     of Tax-Exempt's Declaration of Trust or By-Laws or of any agreement,
     indenture, instrument, contract, lease or other undertaking to which
     Tax-Exempt is a party or by which it is bound;

          (f) No litigation or administrative proceeding or investigation of or
     before any court or governmental body is presently pending or, to its
     knowledge, threatened against Tax-Exempt or any of its properties or assets
     which, if adversely determined, would materially and adversely affect its
     financial condition or the conduct of its business; and Tax-Exempt knows of
     no facts that might form the basis for the institution of such proceedings
     and is not a party to or subject to the provisions of any order, decree or
     judgment of any court or governmental body which materially and adversely
     affects, or is reasonably likely to materially and adversely effect, its
     business or its ability to consummate the transactions herein contemplated;

          (g) The Statement of Assets and Liabilities, Statement of Operations,
     Statement of Changes in Net Assets and Financial Highlights for the year
     ended December 31, 1999, of Tax-Exempt audited by PricewaterhouseCoopers
     LLP (copies of which have been furnished to Minnesota Series), fairly
     present, in all material respects, Tax-Exempt's financial condition as of
     such date in accordance with generally accepted accounting principles, and
     its results of such operations, changes in its net assets and financial
     highlights for such period, and as of such date there were no known
     liabilities of Tax-Exempt (contingent or otherwise) not disclosed therein
     that would be required in accordance with generally accepted accounting
     principles to be disclosed therein;

          (h) All issued and outstanding Tax-Exempt Shares are, and at the
     Closing Date will be, duly and validly issued and outstanding, fully paid
     and nonassessable with no personal liability attaching to the ownership
     thereof, except as set forth under the caption "Additional Information" in
     Tax-Exempt's current Prospectus incorporated by reference in the
     Registration Statement. Tax-Exempt does not have outstanding any options,
     warrants or other rights to subscribe for or purchase any of its shares;

          (i) The execution, delivery and performance of this Agreement have
     been duly authorized by all necessary action on the part of Tax-Exempt, and
     this Agreement constitutes a valid and binding obligation of Tax-Exempt
     enforceable in accordance with its terms, subject as to enforcement, to
     bankruptcy, insolvency, reorganization, moratorium and other laws relating
     to or affecting creditors rights and to general equity principles. No other
     consents, authorizations or approvals are necessary in connection with
     Tax-Exempt's performance of this Agreement;

          (j) Tax-Exempt Shares to be issued and delivered to Minnesota Series,
     for the account of the Minnesota Series Shareholders, pursuant to the terms
     of this Agreement will at the Closing Date have been duly authorized and,
     when so issued and delivered, will be duly and validly issued Tax-Exempt
     Shares, and will be fully paid and non-assessable with no personal
     liability attaching to the ownership thereof, except as set forth under the
     caption "Capital Stock and Other Securities" in Tax-Exempt's current
     Statement of Additional Information incorporated by reference in the
     Statement of Additional Information to this Registration Statement;

          (k) All material Federal and other tax returns and reports of
     Tax-Exempt required by law to be filed on or before the Closing Date have
     been filed and are correct, and all Federal and other taxes shown as due or
     required to be shown as due on said returns and reports have been paid or
     provision has been made for the payment thereof, and to the best of
     Tax-Exempt's knowledge, no such return is currently under audit and no
     assessment has been asserted with respect to any such return;

          (l) For each taxable year since its inception, Tax-Exempt has met the
     requirements of Subchapter M of the Code for qualification and treatment as
     a "regulated investment company" and neither the

                                       A-6
<PAGE>

     execution or delivery of nor the performance of its obligations under
     this Agreement will adversely affect, and no other events are reasonably
     likely to occur which will adversely affect the ability of Tax-Exempt to
     continue to meet the requirements of Subchapter M of the Code;

          (m) Since December 31, 1999 there has been no change by Tax-Exempt in
     accounting methods, principles, or practices, including those required by
     generally accepted accounting principles;

          (n) The information furnished or to be furnished by Tax-Exempt for use
     in registration statements, proxy materials and other documents which may
     be necessary in connection with the transactions contemplated hereby shall
     be accurate and complete in all material respects and shall comply in all
     material respects with Federal securities and other laws and regulations
     applicable thereto; and

          (o) The Proxy Materials to be included in the Registration Statement
     (only insofar as they relate to Tax-Exempt) will, on the effective date of
     the Registration Statement and on the Closing Date, not contain any untrue
     statement of a material fact or omit to state a material fact required to
     be stated therein or necessary to make the statements therein, in light of
     the circumstances under which such statements were made, not materially
     misleading.

     5.2 Multi-State, on behalf of Minnesota Series, represents and warrants to
Tax-Exempt as follows:

          (a) Multi-State is a series of a validly existing Massachusetts
     business trust with full power to carry on its business as presently
     conducted;

          (b) Multi-State is a duly registered, open-end, management investment
     company, and its registration with the Commission as an investment company
     under the 1940 Act and the registration of its shares under the 1933 Act
     are in full force and effect;

          (c) All of the issued and outstanding shares of beneficial interest of
     Minnesota Series have been offered and sold in compliance in all material
     respects with applicable requirements of the 1933 Act and state securities
     laws. Shares of Minnesota Series are registered in all jurisdictions in
     which they are required to be registered and said registrations, including
     any periodic reports or supplemental filings, are complete and current, all
     fees required to be paid have been paid, and Multi-State is not subject to
     any stop order and is fully qualified to sell its shares in each state in
     which its shares have been registered;

          (d) The current Prospectus and Statement of Additional Information of
     Multi-State conform in all material respects to the applicable requirements
     of the 1933 Act and the 1940 Act and the regulations thereunder and do not
     include any untrue statement of a material fact or omit to state any
     material fact required to be stated therein or necessary to make the
     statements therein, in light of the circumstances under which they were
     made, not misleading;

          (e) Multi-State is not, and the execution, delivery and performance of
     this Agreement will not result, in a material violation of any provision of
     Multi-State's Declaration of Trust or By-Laws or of any agreement,
     indenture, instrument, contract, lease or other undertaking to which
     Multi-State is a party or by which it is bound;

          (f) No litigation or administrative proceeding or investigation of or
     before any court or governmental body is presently pending or, to its
     knowledge, threatened against Minnesota Series or any of its properties or
     assets which, if adversely determined, would materially and adversely
     affect its financial condition or the conduct of its business; and
     Multi-State knows of no facts that might form the basis for the institution
     of such proceedings and is not a party to or subject to the provisions of
     any order, decree or judgment of any court or governmental body which
     materially and adversely affects, or is reasonably likely to materially and
     adversely effect, its business or its ability to consummate the
     transactions herein contemplated;

                                      A-7
<PAGE>

          (g) The Statement of Assets and Liabilities, Statement of Operations,
     Statement of Changes in Net Assets and Financial Highlights of Multi-State
     for the year ended November 30, 1999, audited by PricewaterhouseCoopers LLP
     (copies of which have been or will be furnished to Tax-Exempt) fairly
     present, in all material respects, Minnesota Series' financial condition as
     of such date, and its results of operations, changes in its net assets and
     financial highlights for such period in accordance with generally accepted
     accounting principles, and as of such date there were no known liabilities
     of Minnesota Series (contingent or otherwise) not disclosed therein that
     would be required in accordance with generally accepted accounting
     principles to be disclosed therein;

          (h) Multi-State has no material contracts or other commitments (other
     than this Agreement) that will be terminated with liability to it prior to
     the Closing Date;

          (i) All issued and outstanding shares of Minnesota Series are, and at
     the Closing Date will be, duly and validly issued and outstanding, fully
     paid and nonassessable with no personal liability attaching to the
     ownership thereof, except as set forth under the caption "Capital Stock and
     Other Securities" in Multi-State's current Statement of Additional
     Information incorporated by reference in the Statement of Additional
     Information to this Registration Statement. Minnesota Series does not have
     outstanding any options, warrants or other rights to subscribe for or
     purchase any of its shares, nor is there outstanding any security
     convertible to any of its shares. All such shares will, at the time of
     Closing, be held by the persons and in the amounts set forth in the list of
     shareholders submitted to Tax-Exempt pursuant to paragraph 3.4;

          (j) The execution, delivery and performance of this Agreement will
     have been duly authorized prior to the Closing Date by all necessary action
     on the part of Multi-State, and subject to the approval of Minnesota
     Series' shareholders, this Agreement constitutes a valid and binding
     obligation of Multi-State, enforceable in accordance with its terms,
     subject as to enforcement to bankruptcy, insolvency, reorganization,
     moratorium and other laws relating to or affecting creditors rights and to
     general equity principles. No other consents, authorizations or approvals
     are necessary in connection with Multi-State's performance of this
     Agreement;

          (k) All material Federal and other tax returns and reports of
     Minnesota Series required by law to be filed on or before the Closing Date
     shall have been filed and are correct and all Federal and other taxes shown
     as due or required to be shown as due on said returns and reports have been
     paid or provision has been made for the payment thereof, and to the best of
     Minnesota Series' knowledge, no such return is currently under audit and no
     assessment has been asserted with respect to any such return;

          (l) For each taxable year since its inception, Minnesota Series, has
     met all the requirements of Subchapter M of the Code for qualification and
     treatment as a "regulated investment company" and neither the execution or
     delivery of nor the performance of its obligations under this Agreement
     will adversely affect, and no other events are reasonably likely to occur
     which will adversely affect the ability of Minnesota Series to continue to
     meet the requirements of Subchapter M of the Code;

          (m) At the Closing Date, Multi-State will have good and valid title to
     the Minnesota Series Assets, subject to no liens (other than the
     obligation, if any, to pay the purchase price of portfolio securities
     purchased by Minnesota Series which have not settled prior to the Closing
     Date), security interests or other encumbrances, and full right, power and
     authority to assign, deliver and otherwise transfer such assets hereunder,
     and upon delivery and payment for such assets, Tax-Exempt will acquire good
     and marketable title thereto, subject to no restrictions on the full
     transfer thereof, including any restrictions as might arise under the 1933
     Act;

          (n) On the effective date of the Registration Statement, at the time
     of the meeting of Minnesota Series' shareholders and on the Closing Date,
     the Proxy Materials (exclusive of the currently effective

                                      A-8
<PAGE>

     Tax-Exempt Prospectus contained therein) will (i) comply in all
     material respects with the provisions of the 1933 Act, the Securities
     Exchange Act of 1934, as amended ("1934 Act") and the 1940 Act and the
     regulations thereunder and (ii) not contain any untrue statement of a
     material fact or omit to state a material fact required to be stated
     therein or necessary to make the statements therein not misleading. Any
     other information furnished by Multi-State for use in the Registration
     Statement or in any other manner that may be necessary in connection with
     the transactions contemplated hereby shall be accurate and complete and
     shall comply in all material respects with applicable Federal securities
     and other laws and regulations thereunder;

          (o) Minnesota Series will, on or prior to the Valuation Date, declare
     one or more dividends or other distributions to shareholders that, together
     with all previous dividends and other distributions to shareholders, shall
     have the effect of distributing to the shareholders all of its investment
     company taxable income and net capital gain, if any, through the Valuation
     Date (computed without regard to any deduction for dividends paid);

          (p) Multi-State has maintained or has caused to be maintained on its
     behalf all books and accounts as required of a registered investment
     company in compliance with the requirements of Section 31 of the 1940 Act
     and the Rules thereunder; and

          (q) Minnesota Series is not acquiring Tax-Exempt Shares to be issued
     hereunder for the purpose of making any distribution thereof other than in
     accordance with the terms of this Agreement.

6. CONDITIONS PRECEDENT TO OBLIGATIONS OF MINNESOTA SERIES

     The obligations of Multi-State to consummate the transactions provided for
herein shall be subject, at its election, to the performance by Tax-Exempt of
all the obligations to be performed by it hereunder on or before the Closing
Date and, in addition thereto, the following conditions:

     6.1 All representations and warranties of Tax-Exempt contained in this
Agreement shall be true and correct in all material respects as of the date
hereof and, except as they may be affected by the transactions contemplated by
this Agreement, as of the Closing Date with the same force and effect as if
made on and as of the Closing Date;

     6.2 Tax-Exempt shall have delivered to Minnesota Series, a certificate of
its President and Treasurer, in a form reasonably satisfactory to Multi-State
and dated as of the Closing Date, to the effect that the representations and
warranties of Tax-Exempt made in this Agreement are true and correct at and as
of the Closing Date, except as they may be affected by the transactions
contemplated by this Agreement, and as to such other matters as Multi-State
shall reasonably request;

     6.3 Multi-State, on behalf of Minnesota Series, shall have received a
favorable opinion from Mayer, Brown & Platt, counsel to Tax-Exempt, dated as of
the Closing Date, to the effect that:

          (a) Tax-Exempt is a validly existing Massachusetts business trust, and
     has the power to own all of its properties and assets and to carry on its
     business as presently conducted (Massachusetts counsel may be relied upon
     in delivering such opinion); (b) Tax-Exempt is a duly registered, open-end,
     management investment company, and its registration with the Commission as
     an investment company under the 1940 Act is in full force and effect; (c)
     this Agreement has been duly authorized, executed and delivered by
     Tax-Exempt and, assuming that the Registration Statement complies with the
     1933 Act, the 1934 Act and the 1940 Act and regulations thereunder and
     assuming due authorization, execution and delivery of this Agreement by
     Minnesota Series, is a valid and binding obligation of Tax-Exempt
     enforceable against Tax-Exempt in accordance with its terms, subject as to
     enforcement, to bankruptcy, insolvency, reorgani-

                                      A-9
<PAGE>

     zation, moratorium and other laws relating to or affecting creditors
     rights and to general equity principles; (d) Tax-Exempt Shares to be issued
     to Minnesota Series Shareholders as provided by this Agreement are duly
     authorized and upon such delivery will be validly issued, fully paid and
     non-assessable (except as set forth under the caption "Capital Stock and
     Other Securities" in Tax-Exempt's Statement of Additional Information), and
     no shareholder of Tax-Exempt has any preemptive rights to subscription or
     purchase in respect thereof (Massachusetts counsel may be relied upon in
     delivering such opinion); (e) the execution and delivery of this Agreement
     did not, and the consummation of the transactions contemplated hereby will
     not, violate Tax-Exempt's Declaration of Trust or By-Laws (Massachusetts
     counsel may be relied upon in delivering such opinion); and (f) to the
     knowledge of such counsel, no consent, approval, authorization or order of
     any court or governmental authority of the United States or any state is
     required for the consummation by Tax-Exempt of the transactions
     contemplated herein, except such as have been obtained under the 1933 Act,
     the 1934 Act and the 1940 Act and such as may be required under state
     securities laws; and

     6.4 As of the Closing Date, there shall have been no material change in
the investment objective, policies and restrictions nor any increase in the
investment management fees from those described in Tax-Exempt's Prospectus
dated February 24, 2000 and Statement of Additional Information dated
February 24, 2000.

7. CONDITIONS PRECEDENT TO OBLIGATIONS OF TAX-EXEMPT

     The obligations of Tax-Exempt to complete the transactions provided for
herein shall be subject, at its election, to the performance by Multi-State, on
behalf of Minnesota Series, of all the obligations to be performed by it
hereunder on or before the Closing Date and, in addition thereto, the following
conditions:

     7.1 All representations and warranties of Multi-State contained in this
Agreement shall be true and correct in all material respects as of the date
hereof and, except as they may be affected by the transactions contemplated by
this Agreement, as of the Closing Date with the same force and effect as if
made on and as of the Closing Date;

     7.2 Multi-State shall have delivered to Tax-Exempt at the Closing a
certificate of its President and its Treasurer, in form and substance
satisfactory to Tax-Exempt and dated as of the Closing Date, to the effect that
the representations and warranties of Multi-State made in this Agreement are
true and correct at and as of the Closing Date, except as they may be affected
by the transactions contemplated by this Agreement, and as to such other
matters as Tax-Exempt shall reasonably request;

     7.3 Multi-State shall have delivered to Tax-Exempt a statement of the
Minnesota Series Assets and its liabilities, together with a list of Minnesota
Series' portfolio securities and other assets showing the respective adjusted
bases and holding periods thereof for income tax purposes, as of the Closing
Date, certified by the Treasurer of Multi-State;

     7.4 Multi-State shall have delivered to Tax-Exempt within three business
days after the Closing a letter from PricewaterhouseCoopers LLP dated as of the
Closing Date stating that (a) such firm has performed a limited review of the
Federal and state income tax returns of Multi-State for each of the last three
taxable years and, based on such limited review, nothing came to their
attention that caused them to believe that such returns did not properly
reflect, in all material respects, the Federal and state income tax liabilities
of Minnesota Series for the periods covered thereby, (b) for the period from
November 30, 1999 to and including the Closing Date, such firm has performed a
limited review (based on unaudited financial data) to ascertain the amount of
applicable Federal, state and local taxes and has determined that same either
have been paid or reserves have been established for payment of such taxes,
and, based on such limited review, nothing came to their attention that caused
them to believe that the taxes paid or reserves set aside for payment of such
taxes were not

                                      A-10
<PAGE>

adequate in all material respects for the satisfaction of all Federal, state
and local tax liabilities for the period from November 30, 1999 to and
including the Closing Date and (c) based on such limited reviews, nothing came
to their attention that caused them to believe that Minnesota Series would not
qualify as a regulated investment company for Federal income tax purposes for
any such year or period;

     7.5 Tax-Exempt shall have received at the Closing a favorable opinion from
Mayer, Brown & Platt, counsel to Multi-State, dated as of the Closing Date to
the effect that:

          (a) Multi-State is a validly existing Massachusetts business trust and
     has the power to own all of its properties and assets and to carry on its
     business as presently conducted (Massachusetts counsel may be relied upon
     in delivering such opinion); (b) Multi-State is a duly registered,
     open-end, management investment company under the 1940 Act, and its
     registration with the Commission as an investment company under the 1940
     Act is in full force and effect; (c) this Agreement has been duly
     authorized, executed and delivered by Multi-State and, assuming that the
     Registration Statement complies with the 1933 Act, the 1934 Act and the
     1940 Act and the regulations thereunder and assuming due authorization,
     execution and delivery of this Agreement by Tax-Exempt, is a valid and
     binding obligation of Multi-State enforceable against Multi-State in
     accordance with its terms, subject as to enforcement, to bankruptcy,
     insolvency, reorganization, moratorium and other laws relating to or
     affecting creditors rights and to general equity principles; (d) the
     execution and delivery of this Agreement did not, and the consummation of
     the transactions contemplated hereby will not, violate Multi-State's
     Declaration of Trust or By-Laws (Massachusetts counsel may be relied upon
     in delivering such opinion); and (e) to the knowledge of such counsel, no
     consent, approval, authorization or order of any court or governmental
     authority of the United States or any state is required for the
     consummation by Multi-State of the transactions contemplated herein, except
     such as have been obtained under the 1933 Act, the 1934 Act and the 1940
     Act and such as may be required under state securities laws; and

     7.6 On the Closing Date, the Minnesota Series Assets shall include no
assets that Tax-Exempt, by reason of limitations of the fund's Declaration of
Trust or otherwise, may not properly acquire.

8. FURTHER CONDITIONS PRECEDENT TO OBLIGATIONS OF TAX-EXEMPT
   AND MINNESOTA SERIES

     The obligations of Multi-State, on behalf of Minnesota Series, and
Tax-Exempt hereunder are each subject to the further conditions that on or
before the Closing Date:

     8.1 This Agreement and the transactions contemplated herein shall have
been approved by the requisite vote of the holders of the outstanding shares of
Minnesota Series in accordance with the provisions of Multi-State's Declaration
of Trust, and certified copies of the resolutions evidencing such approval
shall have been delivered to Tax-Exempt;

     8.2 On the Closing Date, no action, suit or other proceeding shall be
pending before any court or governmental agency in which it is sought to
restrain or prohibit, or obtain damages or other relief in connection with,
this Agreement or the transactions contemplated herein;

     8.3 All consents of other parties and all other consents, orders and
permits of Federal, state and local regulatory authorities (including those of
the Commission and of state Blue Sky and securities authorities, including
"no-action" positions of and exemptive orders from such Federal and state
authorities) deemed necessary by Tax-Exempt or Multi-State to permit
consummation, in all material respects, of the transactions contemplated herein
shall have been obtained, except where failure to obtain any such consent,
order or permit would not involve risk of a material adverse effect on the
assets or properties of Tax-Exempt or Minnesota Series;

                                      A-11
<PAGE>

     8.4 The Registration Statement shall have become effective under the 1933
Act, no stop orders suspending the effectiveness thereof shall have been issued
and, to the best knowledge of the parties hereto, no investigation or
proceeding for that purpose shall have been instituted or be pending,
threatened or contemplated under the 1933 Act;

     8.5 Minnesota Series shall have declared and paid a dividend or dividends
and/or other distribution or distributions that, together with all previous
such dividends or distributions, shall have the effect of distributing to the
Minnesota Series Shareholders all of Minnesota Series' investment company
taxable income (computed without regard to any deduction for dividends paid)
and all of its net capital gain (after reduction for any capital loss
carry-forward and computed without regard to any deduction for dividends paid)
for all taxable years ending on or before the Closing Date; and

     8.6 The parties shall have received the opinion of the law firm of Mayer,
Brown & Platt (based on such representations as such law firm shall reasonably
request), addressed to Tax-Exempt and Multi-State, on behalf of Minnesota
Series, which opinion may be relied upon by the shareholders of Minnesota
Series, substantially to the effect that, for Federal income tax purposes:

          (a) The transfer of Minnesota Series' assets in exchange for
     Tax-Exempt Shares and the assumption by Tax-Exempt of certain stated
     liabilities of Minnesota Series followed by the distribution by Minnesota
     Series of Tax-Exempt Shares to the Minnesota Series Shareholders in
     exchange for their Minnesota Series shares pursuant to and in accordance
     with the terms of the Reorganization Agreement will constitute a
     "reorganization" within the meaning of Section 368(a)(1)(C) of the Code,
     and Minnesota Series and Tax-Exempt will each be a "party to a
     reorganization" within the meaning of Section 368(b) of the Code;

          (b) No gain or loss will be recognized by Tax-Exempt upon the receipt
     of the assets of Minnesota Series solely in exchange for Tax-Exempt Shares
     and the assumption by Tax-Exempt of the stated liabilities of Minnesota
     Series;

          (c) No gain or loss will be recognized by Minnesota Series upon the
     transfer of the assets of Minnesota Series to Tax-Exempt in exchange for
     Tax-Exempt Shares and the assumption by Tax-Exempt of the stated
     liabilities or upon the distribution of Tax-Exempt Shares to the Minnesota
     Series Shareholders in exchange for their Minnesota Series shares;

          (d) No gain or loss will be recognized by the Minnesota Series
     Shareholders upon the exchange of the Minnesota Series shares for
     Tax-Exempt Shares;

          (e) The aggregate tax basis for Tax-Exempt Shares received by each
     Minnesota Series Shareholder pursuant to the reorganization will be the
     same as the aggregate tax basis of the Minnesota Series Shares held by each
     such Minnesota Series Shareholder immediately prior to the Reorganization;

          (f) The holding period of Tax-Exempt Shares to be received by each
     Minnesota Series Shareholder will include the period during which the
     Minnesota Series Shares surrendered in exchange therefor were held
     (provided such Minnesota Series Shares were held as capital assets on the
     date of the Reorganization);

          (g) The tax basis of the assets of Minnesota Series acquired by
     Tax-Exempt will be the same as the tax basis of such assets to Minnesota
     Series immediately prior to the Reorganization; and

          (h) The holding period of the assets of Minnesota Series in the hands
     of Tax-Exempt will include the period during which those assets were held
     by Minnesota Series.

     Notwithstanding anything herein to the contrary, neither Tax-Exempt nor
Minnesota Series may waive the conditions set forth in this paragraph 8.6.

                                      A-12
<PAGE>

9. FEES AND EXPENSES

     9.1 (a) Tax-Exempt shall bear its expenses incurred in connection with the
entering into, and carrying out of, the provisions of this Agreement, including
legal, accounting, Commission registration fees and Blue Sky expenses.
Minnesota Series and Morgan Stanley Dean Witter Advisors Inc. shall bear, as
set forth in the Proxy Statement and Prospectus contained in the Registration
Statement, certain expenses incurred in connection with the entering into and
carrying out of the provisions of this Agreement, including legal and
accounting fees, printing, filing and proxy solicitation expenses incurred in
connection with the consummation of the transactions contemplated herein.
Minnesota Series shall bear any other expenses in connection with the
provisions of this Agreement including certain other legal and accounting fees
and portfolio transfer taxes (if any) incurred in connection with the
consummation of the transactions contemplated herein.

     (b) In the event the transactions contemplated herein are not consummated
by reason of Minnesota Series being either unwilling or unable to go forward
(other than by reason of the nonfulfillment or failure of any condition to
Minnesota Series' obligations specified in this Agreement), Minnesota Series'
only obligation hereunder shall be to reimburse Tax-Exempt for all reasonable
out-of-pocket fees and expenses incurred by Tax-Exempt in connection with those
transactions.

     (c) In the event the transactions contemplated herein are not consummated
by reason of Tax-Exempt being either unwilling or unable to go forward (other
than by reason of the nonfulfillment or failure of any condition to
Tax-Exempt's obligations specified in this Agreement), Tax-Exempt's only
obligation hereunder shall be to reimburse Minnesota Series for all reasonable
out-of-pocket fees and expenses incurred by Minnesota Series in connection with
those transactions.

10. ENTIRE AGREEMENT; SURVIVAL OF WARRANTIES

     10.1 This Agreement constitutes the entire agreement between the parties.

     10.2 The representations, warranties and covenants contained in this
Agreement or in any document delivered pursuant hereto or in connection
herewith shall survive the consummation of the transactions contemplated
herein, except that the representations, warranties and covenants of
Multi-State hereunder shall not survive the dissolution and complete
liquidation of Minnesota Series in accordance with Section 1.9.

11. TERMINATION

     11.1 This Agreement may be terminated and the transactions contemplated
hereby may be abandoned at any time prior to the Closing:

          (a) by the mutual written consent of Multi-State, on behalf of
     Minnesota Series, and Tax-Exempt;

          (b) by either Tax-Exempt or Multi-State, on behalf of Minnesota
     Series, by notice to the other, without liability to the terminating party
     on account of such termination (providing the terminating party is not
     otherwise in material default or breach of this Agreement) if the Closing
     shall not have occurred on or before September 30, 2000; or

          (c) by either Tax-Exempt or Multi-State, on behalf of Minnesota
     Series, in writing without liability to the terminating party on account of
     such termination (provided the terminating party is not otherwise in
     material default or breach of this Agreement), if (i) the other party shall
     fail to perform in any material respect its agreements contained herein
     required to be performed on or prior to the Closing Date, (ii) the other
     party materially breaches any of its representations, warranties or
     covenants contained herein, (iii) the Minnesota Series shareholders fail to
     approve this Agreement at any meeting called for such

                                      A-13
<PAGE>

     purpose at which a quorum was present or (iv) any other condition
     herein expressed to be precedent to the obligations of the terminating
     party has not been met and it reasonably appears that it will not or cannot
     be met.

     11.2 (a) Termination of this Agreement pursuant to paragraphs 11.1 (a) or
(b) shall terminate all obligations of the parties hereunder and there shall be
no liability for damages on the part of Tax-Exempt or Multi-State, or the
trustees or officers of Tax-Exempt or Multi-State, to any other party or its
trustees or officers.

          (b) Termination of this Agreement pursuant to paragraph 11.1 (c) shall
     terminate all obligations of the parties hereunder and there shall be no
     liability for damages on the part of Tax-Exempt or Multi-State, or the
     trustees or officers of Tax-Exempt or Multi-State, except that any party in
     breach of this Agreement shall, upon demand, reimburse the non-breaching
     party for all reasonable out-of-pocket fees and expenses incurred in
     connection with the transactions contemplated by this Agreement, including
     legal, accounting and filing fees.

12. AMENDMENTS

     This Agreement may be amended, modified or supplemented in such manner as
may be mutually agreed upon in writing by the parties.

13. MISCELLANEOUS

     13.1 The article and paragraph headings contained in this Agreement are
for reference purposes only and shall not affect in any way the meaning or
interpretation of this Agreement.

     13.2 This Agreement may be executed in any number of counterparts, each of
which shall be deemed an original.

     13.3 This Agreement shall be governed by and construed in accordance with
the laws of the Commonwealth of Massachusetts.

     13.4 This Agreement shall bind and inure to the benefit of the parties
hereto and their respective successors and assigns, but no assignment or
transfer hereof or of any rights or obligations hereunder shall be made by any
party without the written consent of the other party. Nothing herein expressed
or implied is intended or shall be construed to confer upon or give any person,
firm or corporation, other than the parties hereto and their respective
successors and assigns, any rights or remedies under or by reason of this
Agreement.

     13.5 The obligations and liabilities of Tax-Exempt hereunder are solely
those of Tax-Exempt. It is expressly agreed that no shareholder, nominee,
trustee, officer, agent, or employee of Tax-Exempt shall be personally liable
hereunder. The execution and delivery of this Agreement have been authorized by
the trustees of Tax-Exempt and signed by authorized officers of Tax-Exempt
acting as such, and neither such authorization by such trustees nor such
execution and delivery by such officers shall be deemed to have been made by
any of them individually or to impose any liability on any of them personally.

     13.6 The obligations and liabilities of Multi-State hereunder are solely
those of Multi-State. It is expressly agreed that no shareholder, nominee,
trustee, officer, agent, or employee of Minnesota Series shall be personally
liable hereunder. The execution and delivery of this Agreement have been
authorized by the trustees of Multi-State and signed by authorized officers of
Multi-State acting as such, and neither such authorization by such trustees nor
such execution and delivery by such officers shall be deemed to have been made
by any of them individually or to impose any liability on any of them
personally.

                                      A-14
<PAGE>

     IN WITNESS WHEREOF, each of the parties hereto has caused this Agreement
to be executed by a duly authorized officer.

          MORGAN STANLEY DEAN WITTER MULTI-STATE MUNICIPAL SERIES TRUST
                          ON BEHALF OF MINNESOTA SERIES

                              By: /s/ CHARLES A. FIUMEFREDDO
                                 ----------------------------------------------
                                 Name:  Charles A. Fiumefreddo
                                 Title: Chairman

             MORGAN STANLEY DEAN WITTER TAX-EXEMPT SECURITIES TRUST

                              By: /s/ BARRY FINK
                                 ----------------------------------------------
                                 Name:  Barry Fink
                                 Title: Vice President

                                      A-15
<PAGE>

                                                 PROSPECTUS - FEBRUARY 24, 2000

                                                                      Exhibit B

MORGAN STANLEY DEAN WITTER
- --------------------------------------------------------------------------------
                                                    TAX-EXEMPT SECURITIES TRUST


[GRAPHIC OMITTED]


A MUTUAL FUND THAT SEEKS TO PROVIDE A HIGH LEVEL OF CURRENT INCOME EXEMPT FROM
FEDERAL INCOME TAX, CONSISTENT WITH THE PRESERVATION OF CAPITAL


  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.


<PAGE>



CONTENTS

The Fund                    Investment Objective ..........................    1
                            Principal Investment Strategies ...............    1
                            Principal Risks ...............................    2
                            Past Performance ..............................    4
                            Fees and Expenses .............................    6
                            Additional Investment Strategy Information ....    7
                            Additional Risk Information ...................    8
                            Fund Management ...............................    9

Shareholder Information     Pricing Fund Shares ...........................   10
                            How to Buy Shares .............................   10
                            How to Exchange Shares ........................   12
                            How to Sell Shares ............................   14
                            Distributions .................................   16
                            Tax Consequences ..............................   16
                            Share Class Arrangements ......................   18

Financial Highlights        ...............................................   25

Our Family of Funds         .................................. Inside Back Cover


         This Prospectus contains important information about the Fund.
           Please read it carefully and keep it for future reference.



<PAGE>


THE FUND


[GRAPHIC OMITTED]


INVESTMENT OBJECTIVE
- --------------------

Morgan Stanley Dean Witter Tax-Exempt Securities Trust (the "Fund") seeks to
provide a high level of current income exempt from federal income tax,
consistent with the preservation of capital.


[GRAPHIC OMITTED]

PRINCIPAL INVESTMENT STRATEGIES
- -------------------------------

(sidebar)
INCOME
An investment objective having the goal of selecting securities to pay out
income rather than rise in price.
(end sidebar)

The Fund will normally invest at least 80% of its total assets in securities
that pay interest exempt from federal income taxes. The Fund's "Investment
Manager," Morgan Stanley Dean Witter Advisors Inc., generally invests the Fund's
assets in municipal obligations. Municipal obligations are bonds, notes or
short-term commercial paper issued by state governments, local governments, and
their respective agencies. At least 75% of these municipal obligations will have
the following ratings at the time of purchase:


o  municipal bonds --                 within the three highest grades by
                                      Moody's Investors Service Inc.
                                      ("Moody's"), Standard & Poor's
                                      Corporation ("S&P"), or Fitch IBCA,
                                      Inc. ("Fitch");

o  municipal notes --                 within the two highest grades or, if
                                      not rated, have outstanding bonds
                                      within the three highest grades by
                                      Moody's, S&P or Fitch; and

o  municipal commercial paper --      within the highest grade by
                                      Moody's, S&P or Fitch.


The Fund may invest up to 25% of its assets in municipal obligations that are
rated below the limits stated above or are not rated by those rating agencies.
However, the Fund may only invest up to 5% of its assets in municipal
obligations rated below investment grade or, if unrated, of comparable quality
as determined by the Investment Manager (commonly known as "junk bonds").


The Fund may invest up to 10% of its assets in inverse floating rate municipal
obligations. The interest rates on these obligations generally move in the
reverse direction of market interest rates. If market interest rates fall, the
interest rate on the obligations will increase and if market interest rates
increase, the interest rate on the obligations will fall.


The Fund may invest up to 20% of its assets in taxable money market instruments
or securities that pay interest income subject to the "alternative minimum tax,"
and some


                                                                              1

<PAGE>


taxpayers may have to pay tax on a Fund distribution of this income. The Fund
therefore may not be a suitable investment for these investors. See the "Tax
Consequences" section for more details.


Municipal bonds, notes and commercial paper are commonly classified as either
"general obligation" or "revenue." General obligation bonds, notes, and
commercial paper are secured by the issuer's faith and credit including its
taxing power, for payment of principal and interest. Revenue bonds, notes and
commercial paper, however, are generally payable from a specific source of
income. They are issued to fund a wide variety of public and private projects in
sectors such as transportation, education and industrial development. Included
within the revenue category are participations in lease obligations. The Fund's
municipal obligation investments may include zero coupon securities, which are
purchased at a discount and accrue interest, but make no interest payments until
maturity.


In pursuing the Fund's investment objective, the Investment Manager has
considerable leeway in deciding which investments it buys, holds or sells on a
day-to-day basis -- and which investment strategies it uses. For example, the
Investment Manager in its discretion may determine to use some permitted
investment strategies while not using others.


[GRAPHIC OMITTED]

PRINCIPAL RISKS
- ---------------

There is no assurance that the Fund will achieve its investment objective. The
Fund's share price and yield will fluctuate with changes in the market value of
the Fund's portfolio securities. When you sell Fund shares, they may be worth
less than what you paid for them and, accordingly, you can lose money investing
in this Fund.

Credit and Interest Rate Risks. Municipal obligations, like other debt
securities, are subject to two types of risks: credit risk and interest rate
risk.

Credit risk refers to the possibility that the issuer of a security will be
unable to make interest payments and/or repay the principal on its debt. In the
case of revenue bonds, notes or commercial paper, for example, the credit risk
is the possibility that the user fees from a project or other specified revenue
sources are insufficient to meet interest and/or principal payment obligations.
The issuers of private activity bonds, used to finance projects in sectors such
as industrial development and pollution control, also may be negatively impacted
by the general credit of the user of the project.

Interest rate risk refers to fluctuations in the value of a fixed-income
security resulting from changes in the general level of interest rates. When the
general level of interest rates goes up, the prices of most fixed-income
securities go down. When the general level of interest rates goes down, the
prices of most fixed-income securities go up. Zero coupon securities are
typically subject to greater price fluctuations than comparable


2

<PAGE>


securities that pay current interest. As a general illustration of the
relationship between fixed-income securities and interest rates, the following
table shows how interest rates affect bond prices.


                      HOW INTEREST RATES AFFECT BOND PRICES

                                        PRICE PER $1,000 OF A MUNICIPAL BOND
                                                 IF INTEREST RATES:
                                           INCREASE*          DECREASE**
YEARS TO
MATURITY   BOND MATURITY    COUPON            1%      2%         1%        2%
  1             2000         3.95%           $990    $981      $1,010    $1,020
  5             2004         4.70%           $957    $916      $1,045    $1,093
  10            2009         5.05%           $926    $858      $1,082    $1,171
  20            2019         5.80%           $892    $799      $1,128    $1,278
  30            2029         5.95%           $875    $773      $1,155    $1,350

Source: Municipal Market Data (a division of Thomson Financial Municipal Group);
"Aaa" yield curve as of 12/31/99. The table is not representative of price
changes for inverse floating rate municipal obligations which typically respond
to changes in interest rates to a greater extent than comparable obligations. In
addition, the table is an illustration and does not represent expected yields or
share price changes of any Morgan Stanley Dean Witter mutual fund.

* Assumes no effect from market discount calculation.

**Assumes bonds are non-callable.

The Fund is not limited as to the maturities of the municipal obligations in
which it may invest. Thus, a rise in the general level of interest rates may
cause the price of the Fund's portfolio securities to fall substantially.


Inverse Floating Rate Municipal Obligations. The inverse floating rate municipal
obligations in which the Fund may invest are typically created through a
division of a fixed rate municipal obligation into two separate instruments, a
short-term obligation and a long-term obligation. The interest rate on the
short-term obligation is set at periodic auctions. The interest rate on the
long-term obligation is the rate the issuer would have paid on the fixed income
obligation: (i) plus the difference between such fixed rate and the rate on the
short-term obligation, if the short-term rate is lower than the fixed rate; or
(ii) minus such difference if the interest rate on the short-term obligation is
higher than the fixed rate. Inverse floating rate municipal obligations offer
the potential for higher income than is available from fixed rate obligations of
comparable maturity and credit rating. They also carry greater risks. In
particular, the prices of inverse floating rate municipal obligations are more
volatile, i.e., they increase and decrease in response to changes in interest
rates to a greater extent than comparable fixed rate obligations.


                                                                               3

<PAGE>


Other Risks. The performance of the Fund also will depend on whether the
Investment Manager is successful in pursuing the Fund's investment strategy. The
Fund is also subject to other risks from its permissible investments including
the risks associated with its lease obligations investments. For more
information about these risks, see the "Additional Risk Information" section.


Shares of the Fund are not bank deposits and are not guaranteed or insured by
the FDIC or any other government agency.

4

<PAGE>


[GRAPHIC OMITTED]

PAST PERFORMANCE
- ----------------

The bar chart and table below provide some indication of the risks of investing
in the Fund. The Fund's past performance does not indicate how the Fund will
perform in the future.

(sidebar)
ANNUAL TOTAL RETURNS
This chart shows how the performance of the Fund's Class D shares has varied
from year to year over the past 10 calendar years.
(end sidebar)

[GRAPHIC OMITTED]

                      ANNUAL TOTAL RETURNS--CALENDAR YEARS

                           YEAR           PERCENTAGE
                           1990              5.86%
                           1991             12.71%
                           1992              9.09%
                           1993             11.23%
                           1994             -5.55%
                           1995             17.37%
                           1996              3.61%
                           1997              8.73%
                           1998              6.11%
                           1999             -2.71%

The bar chart reflects the performance of Class D shares. All shares held prior
to the Fund adopting its Multi-Class Structure on July 28, 1997 were designated
Class D Shares. Prior to that date, shares were subject to a front-end sales
charge, which is not reflected in the bar chart. The performance of the other
Classes will differ because the Classes have different ongoing fees.


(sidebar)
AVERAGE ANNUAL TOTAL RETURNS
This table compares the Fund's average annual returns with those of a broad
measure of market performance over time. The Fund's returns include the maximum
applicable sales charge for each Class and assume you sold your shares at the
end of each period.
(end sidebar)


During the periods shown in the bar chart, the highest return for a calendar
quarter was 6.89% (quarter ended March 31, 1995) and the lowest return for a
calendar quarter was -5.50% (quarter ended March 31, 1994).

AVERAGE ANNUAL TOTAL RETURNS (AS OF DECEMBER 31, 1999)
                                      PAST 1 YEAR   PAST 5 YEARS   PAST 10 YEARS
Class A(1)                                 -6.95%        5.27%          5.73%
Class B(2)                                 -7.86%         --             --
Class C(2)                                 -4.29%         --             --
Class D(3)                                 -2.71%        6.42%          6.44%
Lehman Brothers Municipal Bond Index(4)    -2.06%        6.91%          6.89%

1   Prior to July 28, 1997 the Fund offered only one class of shares. Because
    the distribution arrangement for Class A most closely resembled the
    distribution arrangement applicable prior to the implementation of multiple
    classes (i.e., Class A is sold with a front-end sales charge), historical
    performance information has been restated to reflect the actual maximum
    sales charge applicable to Class A (i.e., 4.25%) as compared to the 4.00%
    sales charge in effect prior to July 28, 1997. In addition, Class A shares
    are now subject to an ongoing 12b-1 fee which is reflected in the restated
    performance for that class.
2   Classes B and C commenced operations on July 28, 1997.
3   Because all shares of the Fund held prior to July 28, 1997 were designated
    Class D shares, the Fund's historical performance has been restated to
    reflect the absence of any sales charge.
4   The Lehman Brothers Municipal Bond Index tracks the performance of Municipal
    bonds with maturities of 2 years or more and a minimum credit rating of Baa
    or BBB, as measured by Moody's Investor Service, Inc. or Standard & Poor's
    Corp. The Index does not include any expenses, fees, or changes. The Index
    is unmanaged and should not be considered an investment.


                                                                               5

<PAGE>


[GRAPHIC OMITTED]


FEES AND EXPENSES
- -----------------

The table below briefly describes the fees and expenses that you may pay if you
buy and hold shares of the Fund. The Fund offers four Classes of shares: Classes
A, B, C and D. Each Class has a different combination of fees, expenses and
other features. The Fund does not charge account or exchange fees. See the
"Share Class Arrangements" section for further fee and expense information.

(sidebar)
SHAREHOLDER FEES
These fees are paid directly from your investment.
(end sidebar)

<TABLE>
<CAPTION>
                                                    CLASS A     CLASS B     CLASS C     CLASS D
  SHAREHOLDER FEES
<S>                                                <C>         <C>         <C>         <C>
Maximum sales charge (load) imposed on
purchases (as a percentage of offering price)        4.25%1      None        None        None
Maximum deferred sales charge (load) (as a
percentage based on the lesser of the offering
price or net asset value at redemption)              None2       5.00%3      1.00%4      None

(sidebar)
ANNUAL FUND OPERATING EXPENSES
These expenses are deducted from the Fund's assets and are based on expenses
paid for the fiscal year ended December 31, 1999.
(end sidebar)

ANNUAL FUND OPERATING EXPENSES
Management fee                                       0.44%       0.44%       0.44%       0.44%
Distribution and service (12b-1) fees                0.13%       0.60%       0.70%       None
Other expenses                                       0.07%       0.07%       0.07%       0.07%
Total annual Fund operating expenses                 0.64%       1.11%       1.21%       0.51%
</TABLE>

1  Reduced for purchases of $25,000 and over.
2  Investments that are not subject to any sales charge at the time of purchase
   are subject to a contingent deferred sales charge ("CDSC") of 1.00% that
   will be imposed if you sell your shares within one year after purchase,
   except for certain specific circumstances.
3  The CDSC is scaled down to 1.00% during the sixth year, reaching zero
   thereafter. See "Share Class Arrangements" for a complete discussion of
   the CDSC.
4  Only applicable if you sell your shares within one year after purchase.









6

<PAGE>


EXAMPLE

This example is intended to help you compare the cost of investing in the Fund
with the cost of investing in other mutual funds.


The example assumes that you invest $10,000 in the Fund, your investment has a
5% return each year, and the Fund's operating expenses remain the same. Although
your actual costs may be higher or lower, the tables below show your costs at
the end of each period based on these assumptions depending upon whether or not
you sell (redeem) your shares at the end of each period.

<TABLE>
<CAPTION>
                   IF YOU SOLD YOUR SHARES:                IF YOU HELD YOUR SHARES:
<S>         <C>      <C>       <C>       <C>        <C>       <C>       <C>       <C>
            1 YEAR   3 YEARS   5 YEARS   10 YEARS    1 YEAR   3 YEARS   5 YEARS   10 YEARS
  CLASS A    $488      $621      $767     $1,189      $488     $621      $767      $1,189
  CLASS B    $613      $653      $812     $1,352      $113     $353      $612      $1,352
  CLASS C    $223      $384      $665     $1,466      $123     $384      $665      $1,466
  CLASS D    $52       $164      $285     $640        $52      $164      $285      $640
</TABLE>

Long-term shareholders of Class B and Class C may pay more in sales charges,
including distribution fees, than the economic equivalent of the maximum
front-end sales charges permitted by the NASD.




[GRAPHIC OMITTED]


ADDITIONAL INVESTMENT STRATEGY INFORMATION
- ------------------------------------------

This section provides additional information relating to the Fund's principal
strategies.

Lease Obligations. Included within the revenue bonds category are participations
in lease obligations or installment purchase contracts of municipalities.
Generally, state and local agencies or authorities issue lease obligations to
acquire equipment and facilities for public and private purposes.


Defensive Investing. The Fund may take temporary "defensive" positions in
attempting to respond to adverse market conditions. The Fund may invest any
amount of its assets in taxable securities, or in tax-exempt securities subject
to the federal alternative minimum tax for individual shareholders when the
Investment Manager believes it is advisable to do so. Although taking a
defensive posture is designed to protect the Fund from an anticipated market
downturn, it could have the effect of reducing the Fund's ability to provide
tax-exempt income. When the Fund takes a defensive position, it may not achieve
its investment objective.


The percentage limitations relating to the composition of the Fund's portfolio
apply at the time the Fund acquires an investment and refer to the Fund's net
assets, unless otherwise noted. Subsequent percentage changes that result from
market fluctuations


                                                                               7

<PAGE>


will not require the Fund to sell any portfolio security. The Fund may change
its principal investment strategies without shareholder approval; however, you
would be notified of any changes.




[GRAPHIC OMITTED]


ADDITIONAL RISK INFORMATION
- ---------------------------

This section provides additional information relating to the principal risks of
investing in the Fund.


Bond Insurance Risk. Many of the municipal obligations the Fund invests in will
be covered by insurance at the time of issuance or at a later date. Such
insurance covers the remaining term of the security. Insured municipal
obligations would generally be assigned a lower rating if the rating were based
primarily on the credit quality of the issuer without regard to the insurance
feature. If the claims-paying ability of the insurer were downgraded, the
ratings on the municipal obligations it insures may also be downgraded.


Lease Obligations. Lease obligations may have risks not normally associated with
general obligation or other revenue bonds. Leases and installment purchase or
conditional sale contracts (which may provide for title to the leased asset to
pass eventually to the issuer) have developed, in part, as a means for
governmental issuers to acquire property and equipment without the necessity of
complying with the constitutional and statutory requirements generally
applicable for the issuance of debt. Certain lease obligations contain
"non-appropriation" clauses that provide that the governmental issuer has no
obligation to make future payments under the lease or contract unless money is
appropriated for that purpose by the appropriate legislative body on an annual
or other periodic basis. Consequently, continued lease payments on those lease
obligations containing "non-appropriation" clauses are dependent on future
legislative actions. If these legislative actions do not occur, the holders of
the lease obligation may experience difficulty in exercising their rights,
including disposition of the property.


8

<PAGE>



[GRAPHIC OMITTED]


FUND MANAGEMENT
- ----------------

(sidebar)
MORGAN STANLEY DEAN WITTER ADVISORS INC.
The Investment Manager is widely recognized as a leader in the mutual fund
industry and together with Morgan Stanley Dean Witter Services Company Inc.,
its wholly-owned subsidiary, had approximately $145 billion in assets under
management as of January 31, 2000.
(end sidebar)

The Fund has retained the Investment Manager -- Morgan Stanley Dean Witter
Advisors Inc. -- to provide administrative services, manage its business affairs
and invest its assets, including the placing of orders for the purchase and sale
of portfolio securities. The Investment Manager is a wholly-owned subsidiary of
Morgan Stanley Dean Witter & Co., a preeminent global financial services firm
that maintains leading market positions in each of its three primary businesses:
securities, asset management and credit services. Its main business office is
located at Two World Trade Center, New York, NY 10048.


The Fund's portfolio is managed within the Investment Manager's Tax-Exempt
Group. James F. Willison, Senior Vice President and Director of the Tax-Exempt
Fixed-Income Group of the Investment Manager has been a primary portfolio
manager of the Fund since its inception. Joseph R. Arcieri, Senior Vice
President of the Investment Manager, has been a primary portfolio manager of the
Fund since February 1997. Mr. Willison and Mr. Arcieri have been portfolio
managers with the Investment Manager for over five years.


The Fund pays the Investment Manager a monthly management fee as full
compensation for the services and facilities furnished to the Fund, and for Fund
expenses assumed by the Investment Manager. The fee is based on the Fund's
average daily net assets. For the fiscal year ended December 31, 1999, the Fund
accrued total compensation to the Investment Manager amounting to 0.44% of the
Fund's average daily net assets.


                                                                               9

<PAGE>


SHAREHOLDER INFORMATION

[GRAPHIC OMITTED]

PRICING FUND SHARES
- -------------------

The price of Fund shares (excluding sales charges), called "net asset value," is
based on the value of the Fund's portfolio securities. While the assets of each
Class are invested in a single portfolio of securities, the net asset value of
each Class will differ because the Classes have different ongoing distribution
fees.

The net asset value per share of the Fund is determined once daily at 4:00 p.m.
Eastern time on each day that the New York Stock Exchange is open (or, on days
when the New York Stock Exchange closes prior to 4:00 p.m., at such earlier
time). Shares will not be priced on days that the New York Stock Exchange is
closed.

The Fund's portfolio securities (except for short-term taxable debt securities
and certain other investments) are valued by an outside independent pricing
service. The service uses a computerized grid matrix of tax-exempt securities
and its evaluations in determining what it believes is the fair value of the
portfolio securities. The Fund's Board of Trustees believes that timely and
reliable market quotations are generally not readily available to the Fund to
value tax-exempt securities and the valuations that the pricing service supplies
are more likely to approximate the fair value of the securities.

An exception to the Fund's general pricing policy concerns its short-term debt
securities. Debt securities with remaining maturities of sixty days or less at
the time of purchase are valued at amortized cost. However, if the cost does not
reflect the securities' market value, these securities will be valued at their
fair value.


[GRAPHIC OMITTED]

HOW TO BUY SHARES
- -----------------

(sidebar)
CONTACTING A FINANCIAL ADVISOR
If you are new to the Morgan Stanley Dean Witter Family of Funds and would like
to contact a Financial Advisor, call (877) 937-MSDW (toll-free) for the
telephone number of the Morgan Stanley Dean Witter office nearest you. You may
also access our office locator on our Internet site at:
www.msdw.com/individual/funds
(end sidebar)

You may open a new account to buy Fund shares or buy additional Fund shares for
an existing account by contacting your Morgan Stanley Dean Witter Financial
Advisor. Your Financial Advisor or other authorized financial representative
will assist you, step-by-step, with the procedures to invest in the Fund. You
may also purchase shares directly by calling the Fund's transfer agent and
requesting an application.

Because every investor has different immediate financial needs and long-term
investment goals, the Fund offers investors four Classes of shares: Classes A,
B, C and D. Class D shares are only offered to a limited group of investors.
Each Class of shares offers a distinct structure of sales charges, distribution
and service fees, and other features that are designed to address a variety of
needs. Your Financial Advisor or other authorized financial representative can
help you decide which Class may be most appropriate for you. When purchasing
Fund shares, you must specify which Class of shares you wish to purchase.


10

<PAGE>

When you buy Fund shares, the shares are purchased at the next share price
calculated (less any applicable front-end sales charge for Class A shares) after
we receive your purchase order. Your payment is due on the third business day
after you place your purchase order. We reserve the right to reject any order
for the purchase of Fund shares.

(sidebar)
EASYINVEST(SM)
A purchase plan that allows you to transfer money automatically from your
checking or savings account or from a Money Market Fund on a semi-monthly,
monthly or quarterly basis. Contact your Morgan Stanley Dean Witter Financial
Advisor for further information about this service.
(end sidebar)

MINIMUM INVESTMENT AMOUNTS
                                        MINIMUM INVESTMENT
INVESTMENT OPTIONS                   INITIAL      ADDITIONAL
Regular Accounts                     $1,000         $100
EasyInvest(SM)
(Automatically from your
checking or savings account
or Money Market Fund)                $100*          $100*

*  Provided your schedule of investments totals $1,000 in twelve months.

There is no minimum investment amount if you purchase Fund shares through: (1)
the Investment Manager's mutual fund asset allocation plan, (2) a program,
approved by the Fund's distributor, in which you pay an asset-based fee for
advisory, administrative and/or brokerage services, or (3) employer-sponsored
employee benefit plan accounts.


Investment Options for Certain Institutional and Other Investors/Class D Shares.
To be eligible to purchase Class D shares, you must qualify under one of the
investor categories specified in the "Share Class Arrangements" section of this
Prospectus.


Subsequent Investments Sent Directly to the Fund. In addition to buying
additional Fund shares for an existing account by contacting your Morgan Stanley
Dean Witter Financial Advisor, you may send a check directly to the Fund. To buy
additional shares in this manner:

o Write a "letter of instruction" to the Fund specifying the name(s) on the
  account, the account number, the social security or tax identification number,
  the Class of shares you wish to purchase and the investment amount (which
  would include any applicable front-end sales charge). The letter must be
  signed by the account owner(s).

o Make out a check for the total amount payable to: Morgan Stanley Dean Witter
  Tax-Exempt Securities Trust.

o Mail the letter and check to Morgan Stanley Dean Witter Trust FSB at P.O. Box
  1040, Jersey City, NJ 07303.

                                                                              11

<PAGE>


[GRAPHIC OMITTED]

HOW TO EXCHANGE SHARES
- ----------------------

Permissible Fund Exchanges. You may exchange shares of any Class of the Fund for
the same Class of any other continuously offered Multi-Class Fund, or for shares
of a No-Load Fund, a Money Market Fund, North American Government Income Trust
or Short-Term U.S. Treasury Trust, without the imposition of an exchange fee.
See the inside back cover of this prospectus for each Morgan Stanley Dean Witter
Fund's designation as a Multi-Class Fund, No-Load Fund or Money Market Fund. If
a Morgan Stanley Dean Witter Fund is not listed, consult the inside back cover
of that Fund's prospectus for its designation. For purposes of exchanges, shares
of FSC Funds (subject to a front-end sales charge) are treated as Class A shares
of a Multi-Class Fund.


Exchanges may be made after shares of the Fund acquired by purchase have been
held for thirty days. There is no waiting period for exchanges of shares
acquired by exchange or dividend reinvestment. The current prospectus for each
fund describes its investment objective(s), policies and investment minimums,
and should be read before investment. Since exchanges are available only into
continuously offered Morgan Stanley Dean Witter Funds, exchanges are not
available into any new Morgan Stanley Dean Witter Fund during its initial
offering period, or when shares of a particular Morgan Stanley Dean Witter Fund
are not being offered for purchase.


Exchange Procedures. You can process an exchange by contacting your Morgan
Stanley Dean Witter Financial Advisor or other authorized financial
representative. Otherwise, you must forward an exchange privilege authorization
form to the Fund's transfer agent -- Morgan Stanley Dean Witter Trust FSB -- and
then write the transfer agent or call (800) 869-NEWS to place an exchange order.
You can obtain an exchange privilege authorization form by contacting your
Financial Advisor or other authorized financial representative, or by calling
(800) 869-NEWS. If you hold share certificates, no exchanges may be processed
until we have received all applicable share certificates.


An exchange to any Morgan Stanley Dean Witter Fund (except a Money Market Fund)
is made on the basis of the next calculated net asset values of the Funds
involved after the exchange instructions are accepted. When exchanging into a
Money Market Fund, the Fund's shares are sold at their next calculated net asset
value and the Money Market Fund's shares are purchased at their net asset value
on the following business day.


The Fund may terminate or revise the exchange privilege upon required notice.
The check writing privilege is not available for Money Market Fund shares you
acquire in an exchange.


Telephone Exchanges. For your protection when calling Morgan Stanley Dean Witter
Trust FSB, we will employ reasonable procedures to confirm that exchange
instructions communicated over the telephone are genuine. These procedures may
include


12

<PAGE>


requiring various forms of personal identification such as name, mailing
address, social security or other tax identification number. Telephone
instructions also may be recorded.


Telephone instructions will be accepted if received by the Fund's transfer agent
between 9:00 a.m. and 4:00 p.m. Eastern time on any day the New York Stock
Exchange is open for business. During periods of drastic economic or market
changes, it is possible that the telephone exchange procedures may be difficult
to implement, although this has not been the case with the Fund in the past.


Margin Accounts. If you have pledged your Fund shares in a margin account,
contact your Morgan Stanley Dean Witter Financial Advisor or other authorized
financial representative regarding restrictions on the exchange of such shares.


Tax Considerations of Exchanges. If you exchange shares of the Fund for shares
of another Morgan Stanley Dean Witter Fund there are important tax
considerations. For tax purposes, the exchange out of the Fund is considered a
sale of Fund shares -- and the exchange into the other Fund is considered a
purchase. As a result, you may realize a capital gain or loss.


You should review the "Tax Consequences" section and consult your own tax
professional about the tax consequences of an exchange.


Limitations on Exchanges. Certain patterns of exchanges may result in the Fund
limiting or prohibiting, at its discretion, additional purchases and/or
exchanges. Determinations in this regard may be made based on the frequency or
dollar amount of previous exchanges. The Fund will notify you in advance of
limiting your exchange privileges.



CDSC Calculations on Exchanges. See the "Share Class Arrangements" section of
this Prospectus for a further discussion of how applicable contingent deferred
sales charges (CDSCs) are calculated for shares of one Morgan Stanley Dean
Witter Fund that are exchanged for shares of another.


For further information regarding exchange privileges, you should contact your
Morgan Stanley Dean Witter Financial Advisor or call (800) 869-NEWS.


                                                                              13

<PAGE>


[GRAPHIC OMITTED]

HOW TO SELL SHARES
- ------------------

You can sell some or all of your Fund shares at any time. If you sell Class A,
Class B or Class C shares, your net sale proceeds are reduced by the amount of
any applicable CDSC. Your shares will be sold at the next price calculated after
we receive your order to sell as described below.

OPTIONS                PROCEDURES
Contact Your           To sell your shares, simply call your Morgan Stanley
Financial Advisor      Dean Witter Financial Advisor or other authorized
                       financial representative.

[GRAPHIC OMITTED]      Payment will be sent to the address to which the account
                       is registered or deposited in your brokerage account.

By Letter              You can also sell your shares by writing a
                       "letter of instruction" that includes:
                       o your account number;
                       o the dollar amount or the number
                         of shares you wish to sell;
                       o the Class of shares you wish to sell; and
[GRAPHIC OMITTED]      o the signature of each owner as it appears on the
                         account.

                       If you are requesting payment to anyone other than the
                       registered owner(s) or that payment be sent to any
                       address other than the address of the registered
                       owner(s) or pre-designated bank account, you will need a
                       signature guarantee. You can obtain a signature
                       guarantee from an eligible guarantor acceptable to
                       Morgan Stanley Dean Witter Trust FSB. (You should
                       contact Morgan Stanley Dean Witter Trust FSB at (800)
                       869-NEWS for a determination as to whether a particular
                       institution is an eligible guarantor.) A notary public
                       cannot provide a signature guarantee. Additional
                       documentation may be required for shares held by a
                       corporation, partnership, trustee or executor.

                       Mail the letter to Morgan Stanley Dean Witter Trust FSB
                       at P.O. Box 983, Jersey City, NJ 07303. If you hold
                       share certificates, you must return the certificates,
                       along with the letter and any required additional
                       documentation.

                       A check will be mailed to the name(s) and address in
                       which the account is registered, or otherwise according
                       to your instructions.

Systematic             If your investment in all of the Morgan Stanley Dean
Withdrawal Plan        Witter Family of Funds has a total Withdrawal Plan
[GRAPHIC OMITTED]      market value of at least $10,000, you may elect to
                       withdraw amounts of $25 or more, or in any whole
                       percentage of a Fund's balance (provided the amount is
                       at least $25), on a monthly, quarterly, semi-annual or
                       annual basis, from any Fund with a balance of at least
                       $1,000. Each time you add a Fund to the plan, you must
                       meet the plan requirements.

                       Amounts withdrawn are subject to any applicable CDSC. A
                       CDSC may be waived under certain circumstances. See the
                       Class B waiver categories listed in the "Share Class
                       Arrangements" section of this Prospectus.

                       To sign up for the Systematic Withdrawal Plan, contact
                       your Morgan Stanley Dean Witter Financial Advisor or
                       call (800) 869-NEWS. You may terminate or suspend your
                       plan at any time. Please remember that withdrawals from
                       the plan are sales of shares, not Fund "distributions,"
                       and ultimately may exhaust your account balance. The
                       Fund may terminate or revise the plan at any time.
                       --------------------------------------------------------

14

<PAGE>


Payment for Sold Shares. After we receive your complete instructions to sell as
described above, a check will be mailed to you within seven days, although we
will attempt to make payment within one business day. Payment may also be sent
to your brokerage account.


Payment may be postponed or the right to sell your shares suspended, under
unusual circumstances. If you request to sell shares that were recently
purchased by check, your sale will not be effected until it has been verified
that the check has been honored.


Reinstatement Privilege. If you sell Fund shares and have not previously
exercised the reinstatement privilege, you may, within 35 days after the date of
sale, invest any portion of the proceeds in the same Class of Fund shares at
their net asset value and receive a pro rata credit for any CDSC paid in
connection with the sale.


Involuntary Sales. The Fund reserves the right, on sixty days' notice, to sell
the shares of any shareholder (other than shares held in an IRA or 403(b)
Custodial Account) whose shares, due to sales by the shareholder, have a value
below $100, or in the case of an account opened through EasyInvest(SM), if after
12 months the shareholder has invested less than $1,000 in the account.


However, before the Fund sells your shares in this manner, we will notify you
and allow you sixty days to make an additional investment in an amount that will
increase the value of your account to at least the required amount before the
sale is processed. No CDSC will be imposed on any involuntary sale.


Margin Accounts. If you have pledged your Fund shares in a margin account,
contact your Morgan Stanley Dean Witter Financial Advisor or other authorized
financial representative regarding restrictions on the sale of such shares.


                                                                              15

<PAGE>


[GRAPHIC OMITTED]

DISTRIBUTIONS
- -------------

(sidebar)
TARGETED DIVIDENDS(SM)
You may select to have your Fund distributions automatically invested in other
Classes of Fund shares or Classes of another Morgan Stanley Dean Witter Fund
that you own. Contact your Morgan Stanley Dean Witter Financial Advisor for
further information about this service.
(end sidebar)

The Fund passes substantially all of its earnings from income and capital gains
along to its investors as "distributions." The Fund earns interest from
fixed-income investments. These amounts are passed along to Fund shareholders as
"income dividend distributions." The Fund realizes capital gains whenever it
sells securities for a higher price than it paid for them. These amounts may be
passed along as "capital gain distributions."


The Fund declares income dividends separately for each Class. Distributions paid
on Class A and Class D shares usually will be higher than for Class B and Class
C because distribution fees that Class B and Class C pay are higher. Normally,
income dividends are declared on each day the New York Stock Exchange is open
for business, and are distributed to shareholders monthly. Capital gains, if
any, are usually distributed in June and December. The Fund, however, may retain
and reinvest any long-term capital gains. The Fund may at times make payments
from sources other than income or capital gains that represent a return of a
portion of your investment.


Distributions are reinvested automatically in additional shares of the same
Class and automatically credited to your account, unless you request in writing
that all distributions be paid in cash. If you elect the cash option, processing
of your dividend checks begins immediately following the monthly payment date,
and the Fund will mail a monthly dividend check to you normally during the first
seven days of the following month. No interest will accrue on uncashed checks.
If you wish to change how your distributions are paid, your request should be
received by the Fund's transfer agent, Morgan Stanley Dean Witter Trust FSB, at
least five business days prior to the record date of the distributions.


[GRAPHIC OMITTED]

TAX CONSEQUENCES
- ----------------

As with any investment, you should consider how your Fund investment will be
taxed. The tax information in this Prospectus is provided as general
information. You should consult your own tax professional about the tax
consequences of an investment in the Fund.


You need to be aware of the possible tax consequences when:

o The Fund makes distributions; and

o You sell Fund shares, including an exchange to another Morgan Stanley Dean
  Witter Fund.


16

<PAGE>


Taxes on Distributions. Your income dividend distributions are normally exempt
from federal income taxes -- to the extent they are derived from municipal
obligations. Income derived from other portfolio securities may be subject to
federal, state and/or local income taxes.


Income derived from some municipal securities is subject to the federal
"alternative minimum tax." Certain tax-exempt securities whose proceeds are used
to finance private, for-profit organizations are subject to this special tax
system that ensures that individuals pay at least some federal taxes. Although
interest on these securities is generally exempt from federal income tax, some
taxpayers who have many tax deductions or exemptions nevertheless may have to
pay tax on the income.


If you borrow money to purchase shares of the Fund, the interest on the borrowed
money is generally not deductible for personal income tax purposes.


If the Fund makes any capital gain distributions, those distributions will
normally be subject to federal income tax when they are paid, whether you take
them in cash or reinvest them in the Fund shares. Any long-term capital gain
distributions are taxable to you as long-term capital gains, no matter how long
you have owned shares in the Fund.


The Fund may derive gains in part from municipal obligations the Fund purchased
below their principal or face values. All, or a portion, of these gains may be
taxable to you as ordinary income rather than capital gains.


Taxes on Sales. Your sale of Fund shares normally is subject to federal and
state income tax and may result in a taxable gain or loss to you. A sale also
may be subject to local income tax. Your exchange of Fund shares for shares of
another Morgan Stanley Dean Witter Fund is treated for tax purposes like a sale
of your original shares and a purchase of your new shares. Thus, the exchange
may, like a sale, result in a taxable gain or loss to you and will give you a
new tax basis for your new shares.


When you open your Fund account, you should provide your social security or tax
identification number on your investment application. By providing this
information, you will avoid being subject to a federal backup withholding tax of
31% on taxable distributions and redemption proceeds. Any withheld amount would
be sent to the IRS as an advance tax payment.


                                                                              17

<PAGE>


[GRAPHIC OMITTED]

SHARE CLASS ARRANGEMENTS
- ------------------------

The Fund offers several Classes of shares having different distribution
arrangements designed to provide you with different purchase options according
to your investment needs. Your Morgan Stanley Dean Witter Financial Advisor or
other authorized financial representative can help you decide which Class may be
appropriate for you.


The general public is offered three Classes: Class A shares, Class B shares and
Class C shares, which differ principally in terms of sales charges and ongoing
expenses. A fourth Class, Class D shares, is offered only to a limited category
of investors. Shares that you acquire through reinvested distributions will not
be subject to any front-end sales charge or CDSC -- contingent deferred sales
charge. Sales personnel may receive different compensation for selling each
Class of shares. The sales charges applicable to each Class provide for the
distribution financing of shares of that Class.


The chart below compares the sales charge and maximum annual 12b-1 fee
applicable to each Class:

                                                                   MAXIMUM
CLASS     SALES CHARGE                                         ANNUAL 12B-1 FEE
  A       Maximum 4.25% initial sales charge reduced for
          purchases of $25,000 or more; shares sold
          without an initial sales charge are generally
          subject to a 1.0% CDSC during the first year               0.25%
  B       Maximum 5.0% CDSC during the first year
          decreasing to 0% after six years                           0.60%
  C       1.0% CDSC during the first year                            0.70%
  D       None                                                       None


CLASS A SHARES Class A shares are sold at net asset value plus an initial sales
charge of up to 4.25%. The initial sales charge is reduced for purchases of
$25,000 or more according to the schedule below. Investments of $1 million or
more are not subject to an initial sales charge, but are generally subject to a
contingent deferred sales charge, or CDSC, of 1.0% on sales made within one year
after the last day of the month of purchase. The CDSC will be assessed in the
same manner and with the same CDSC waivers as with Class B shares. Class A
shares are also subject to a distribution (12b-1) fee of up to 0.25% of the
average daily net assets of the Class.


18

<PAGE>


The offering price of Class A shares includes a sales charge (expressed as a
percentage of the offering price) on a single transaction as shown in the
following table:


(sidebar)
FRONT-END SALES CHARGE OR FSC
An initial sales charge you pay when purchasing Class A shares that is based on
a percentage of the offering price. The percentage declines based upon the
dollar value of Class A shares you purchase. We offer three ways to reduce your
Class A sales charges -- the Combined Purchase Privilege, Right of Accumulation
and Letter of Intent.
(end sidebar)

<TABLE>
<CAPTION>
                                                   FRONT-END SALES CHARGE
AMOUNT OF                                 PERCENTAGE OF       APPROXIMATE PERCENTAGE
SINGLE TRANSACTION                      PUBLIC OFFERING PRICE   OF NET AMOUNT INVESTED
<S>                                           <C>                     <C>
  Less than $25,000                            4.25%                   4.44%
  $25,000 but less than $50,000                4.00%                   4.17%
  $50,000 but less than $100,000               3.50%                   3.63%
  $100,000 but less than $250,000              2.75%                   2.83%
  $250,000 but less than $1 million            1.75%                   1.78%
  $1 million and over                            0                       0
</TABLE>

The reduced sales charge schedule is applicable to purchases of Class A shares
in a single transaction by:

o A single account (including an individual, trust or fiduciary account).

o Family member accounts (limited to husband, wife and children under the age of
  21).

o Pension, profit sharing or other employee benefit plans of companies and their
  affiliates.

o Tax-exempt organizations.

o Groups organized for a purpose other than to buy mutual fund shares.


Combined Purchase Privilege. You also will have the benefit of reduced sales
charges by combining purchases of Class A shares of the Fund in a single
transaction with purchases of Class A shares of other Multi-Class Funds and
shares of FSC Funds.


Right of Accumulation. You also may benefit from a reduction of sales charges if
the cumulative net asset value of Class A shares of the Fund purchased in a
single transaction, together with shares of other Funds you currently own which
were previously purchased at a price including a front-end sales charge
(including shares acquired through reinvestment of distributions), amounts to
$25,000 or more. Also, if you have a cumulative net asset value of all your
Class A and Class D shares equal to at least $5 million (or $25 million for
certain employee benefit plans), you are eligible to purchase Class D shares of
any Fund subject to the Fund's minimum initial investment requirement.


                                                                              19

<PAGE>


You must notify your Morgan Stanley Dean Witter Financial Advisor or other
authorized financial representative (or Morgan Stanley Dean Witter Trust FSB if
you purchase directly through the Fund), at the time a purchase order is placed,
that the purchase qualifies for the reduced charge under the Right of
Accumulation. Similar notification must be made in writing when an order is
placed by mail. The reduced sales charge will not be granted if: (i)
notification is not furnished at the time of the order; or (ii) a review of the
records of Dean Witter Reynolds or other authorized dealer of Fund shares or the
Fund's transfer agent does not confirm your represented holdings.



Letter of Intent. The schedule of reduced sales charges for larger purchases
also will be available to you if you enter into a written "letter of intent." A
letter of intent provides for the purchase of Class A shares of the Fund or
other Multi-Class Funds or shares of FSC Funds within a thirteen-month period.
The initial purchase under a letter of intent must be at least 5% of the stated
investment goal. To determine the applicable sales charge reduction, you may
also include: (1) the cost of shares of other Morgan Stanley Dean Witter Funds
which were previously purchased at a price including a front-end sales charge
during the 90-day period prior to the distributor receiving the letter of
intent, and (2) the cost of shares of other Funds you currently own acquired in
exchange for shares of Funds purchased during that period at a price including a
front-end sales charge. You can obtain a letter of intent by contacting your
Morgan Stanley Dean Witter Financial Advisor or other authorized financial
representative, or by calling (800) 869-NEWS. If you do not achieve the stated
investment goal within the thirteen-month period, you are required to pay the
difference between the sales charges otherwise applicable and sales charges
actually paid, which may be deducted from your investment.


Other Sales Charge Waivers. In addition to investments of $1 million or more,
your purchase of Class A shares is not subject to a front-end sales charge (or a
CDSC upon sale) if your account qualifies under one of the following categories:


o A trust for which Morgan Stanley Dean Witter Trust FSB provides discretionary
  trustee services.

o Persons participating in a fee-based investment program (subject to all of its
  terms and conditions, including termination fees, mandatory sale or transfer
  restrictions on termination) approved by the Fund's distributor pursuant to
  which they pay an asset-based fee for investment advisory, administrative and/
  or brokerage services.

o A client of a Morgan Stanley Dean Witter Financial Advisor who joined us from
  another investment firm within six months prior to the date of purchase of
  Fund shares, and you used the proceeds from the sale of shares of a
  proprietary mutual fund of that Financial Advisor's previous firm that imposed
  either a front-end or deferred sales charge to purchase Class A shares,
  provided that: (1) you sold the shares not more than 60 days prior to the
  purchase of fund shares, and (2) the sale proceeds were maintained in the
  interim in cash or a money market fund.


20

<PAGE>


o Current or retired Directors/Trustees of the Morgan Stanley Dean Witter Funds,
  such persons' spouses and children under the age of 21, and trust accounts for
  which any of such persons is a beneficiary.

o Current or retired directors, officers and employees of Morgan Stanley Dean
  Witter & Co. and any of its subsidiaries, such persons' spouses and children
  under the age of 21, and trust accounts for which any of such persons is a
  beneficiary.

CLASS B SHARES Class B shares are offered at net asset value with no initial
sales charge but are subject to a contingent deferred sales charge, or CDSC, as
set forth in the table below. For the purpose of calculating the CDSC, shares
are deemed to have been purchased on the last day of the month during which they
were purchased.


(sidebar)
CONTINGENT DEFERRED SALES CHARGE OR CDSC
A fee you pay when you sell shares of certain Morgan Stanley Dean Witter Funds
purchased without an initial sales charge. This fee declines the longer you hold
your shares as set forth in the table.
(end sidebar)

                                             CDSC AS A PERCENTAGE OF
YEAR SINCE PURCHASE PAYMENT MADE                AMOUNT REDEEMED
First                                                5.0%
Second                                               4.0%
Third                                                3.0%
Fourth                                               2.0%
Fifth                                                2.0%
Sixth                                                1.0%
Seventh and thereafter                               None

Each time you place an order to sell or exchange shares, shares with no CDSC
will be sold or exchanged first, then shares with the lowest CDSC will be sold
or exchanged next. For any shares subject to a CDSC, the CDSC will be assessed
on an amount equal to the lesser of the current market value or the cost of the
shares being sold. A lower CDSC schedule applies in most cases to shares of the
Fund acquired in connection with the reorganization of Dean Witter National
Municipal Trust and the Fund on November 7, 1997.


CDSC Waivers. A CDSC, if otherwise applicable, will be waived in the case of:

o Sales of shares held at the time you die or become disabled (within the
  definition in Section 72(m)(7) of the Internal Revenue Code which relates to
  the ability to engage in gainful employment), if the shares are:
  (i) registered either in your name (not a trust) or in the names of you and
  your spouse as joint tenants with right of survivorship; or (ii) held in a
  qualified corporate or self-employed retirement plan, IRA or 403(b) Custodial
  Account, provided in either case that the sale is requested within one year of
  your death or initial determination of disability.

o Sales in connection with the following retirement plan "distributions:" (i)
  lump-sum or other distributions from a qualified corporate or self-employed
  retirement plan following retirement (or, in the case of a "key employee" of a
  "top


                                                                              21

<PAGE>


heavy" plan, following attainment of age 59 1/2); (ii) distributions from an
IRA or 403(b) Custodial Account following attainment of age 59 1/2; or (iii) a
tax-free return of an excess IRA contribution (a "distribution" does not include
a direct transfer of IRA, 403(b) Custodial Account or retirement plan assets to
a successor custodian or trustee).

o  Sales of shares in connection with the Systematic Withdrawal Plan of up
   to 12% annually of the value of each Fund from which plan sales are
   made. The percentage is determined on the date you establish the
   Systematic Withdrawal Plan and based on the next calculated share price.
   You may have this CDSC waiver applied in amounts up to 1% per month, 3%
   per quarter, 6% semi-annually or 12% annually. Shares with no CDSC will
   be sold first, followed by those with the lowest CDSC. As such, the
   waiver benefit will be reduced by the amount of your shares that are not
   subject to a CDSC. If you suspend your participation in the plan, you
   may later resume plan payments without requiring a new determination of
   the account value for the 12% CDSC waiver.

o  Sales of shares if you simultaneously invest the proceeds in the
   Investment Manager's mutual fund asset allocation program, pursuant
   to which investors pay an asset-based fee. Any shares you acquire
   in connection with the Investment Manager's mutual fund asset
   allocation program are subject to all of the terms and conditions
   of that program, including termination fees, mandatory sale or
   transfer restrictions on termination.


All waivers will be granted only following the Fund's distributor receiving
confirmation of your entitlement. If you believe you are eligible for a CDSC
waiver, please contact your Financial Advisor or call (800) 869-NEWS.


Distribution Fee. Class B shares are also subject to an annual 12b-1 fee of
0.60% of the average daily net assets of Class B.


Conversion Feature. After ten (10) years, Class B shares will convert
automatically to Class A shares of the Fund with no initial sales charge. The
ten year period runs from the last day of the month in which the shares were
purchased, or in the case of Class B shares acquired through an exchange, from
the last day of the month in which the original Class B shares were purchased;
the shares will convert to Class A shares based on their relative net asset
values in the month following the ten year period. At the same time, an equal
proportion of Class B shares acquired through automatically reinvested
distributions will convert to Class A shares on the same basis. (Class B shares
held before May 1, 1997, however, will convert to Class A shares in May 2007.)


Currently, the Class B share conversion is not a taxable event; the conversion
feature may be cancelled if it is deemed a taxable event in the future by the
Internal Revenue Service.


22

<PAGE>


If you exchange your Class B shares for shares of a Money Market Fund, a No-Load
Fund, North American Government Income Trust or Short-Term U.S. Treasury Trust,
the holding period for conversion is frozen as of the last day of the month of
the exchange and resumes on the last day of the month you exchange back into
Class B shares.


Exchanging Shares Subject to a CDSC. There are special considerations when you
exchange Fund shares that are subject to a CDSC. When determining the length of
time you held the shares and the corresponding CDSC rate, any period (starting
at the end of the month) during which you held shares of a fund that does not
charge a CDSC will not be counted. Thus, in effect the "holding period" for
purposes of calculating the CDSC is frozen upon exchanging into a fund that does
not charge a CDSC.


For example, if you held Class B shares of the Fund for one year, exchanged to
Class B of another Morgan Stanley Dean Witter Multi-Class Fund for another year,
then sold your shares, a CDSC rate of 4% would be imposed on the shares based on
a two year holding period -- one year for each Fund. However, if you had
exchanged the shares of the Fund for a Money Market Fund (which does not charge
a CDSC) instead of the Multi-Class Fund, then sold your shares, a CDSC rate of
5% would be imposed on the shares based on a one year holding period. The one
year in the Money Market Fund would not be counted. Nevertheless, if shares
subject to a CDSC are exchanged for a Fund that does not charge a CDSC, you will
receive a credit when you sell the shares equal to the distribution (12b-1)
fees, if any, you paid on those shares while in that Fund up to the amount of
any applicable CDSC.


In addition, shares that are exchanged into or from a Morgan Stanley Dean Witter
Fund subject to a higher CDSC rate will be subject to the higher rate, even if
the shares are re-exchanged into a Fund with a lower CDSC rate.

CLASS C SHARES Class C shares are sold at net asset value with no initial sales
charge but are subject to a CDSC of 1.0% on sales made within one year after the
last day of the month of purchase. The CDSC will be assessed in the same manner
and with the same CDSC waivers as with Class B shares.

Distribution Fee. Class C shares are subject to an annual distribution (12b-1)
fee of up to 0.70% of the average daily net assets of that Class. The Class C
shares' distribution fee may cause that Class to have higher expenses and pay
lower dividends than Class A or Class D shares. Unlike Class B shares, Class C
shares have no conversion feature and, accordingly, an investor that purchases
Class C shares may be subject to distribution (12b-1) fees applicable to Class C
shares for an indefinite period.


                                                                              23

<PAGE>


CLASS D SHARES Class D shares are offered without any sales charge on purchases
or sales and without any distribution (12b-1) fee. Class D shares are offered
only to investors meeting an initial investment minimum of $5 million and the
following investor categories:

o Investors participating in the Investment Manager's mutual fund asset
  allocation program (subject to all of its terms and conditions, including
  termination fees, mandatory sale or transfer restrictions on termination)
  pursuant to which they pay an asset-based fee.

o Persons participating in a fee-based investment program (subject to all of its
  terms and conditions, including termination fees, mandatory sale or transfer
  restrictions on termination) approved by the Fund's distributor pursuant to
  which they pay an asset-based fee for investment advisory, administrative and/
  or brokerage services.

o Certain unit investment trusts sponsored by Dean Witter Reynolds.


o Certain other open-end investment companies whose shares are distributed by
  the Fund's distributor.

o Investors who were shareholders of the Dean Witter Retirement Series on
  September 11, 1998 for additional purchases for their former Dean Witter
  Retirement Series accounts.


Meeting Class D Eligibility Minimums. To meet the $5 million initial investment
to qualify to purchase Class D shares you may combine: (1) purchases in a single
transaction of Class D shares of the Fund and other Morgan Stanley Dean Witter
Multi-Class Funds and/or (2) previous purchases of Class A and Class D shares of
Multi-Class Funds and shares of FSC Funds you currently own, along with shares
of Morgan Stanley Dean Witter Funds you currently own that you acquired in
exchange for those shares.

NO SALES CHARGES FOR REINVESTED CASH DISTRIBUTIONS If you receive a cash payment
representing an income dividend or capital gain and you reinvest that amount in
the applicable Class of shares by returning the check within 30 days of the
payment date, the purchased shares would not be subject to an initial sales
charge or CDSC.

PLAN OF DISTRIBUTION (RULE 12B-1 FEES) The Fund has adopted a Plan of
Distribution in accordance with Rule 12b-1 under the Investment Company Act of
1940 with respect to the distribution of Class A, Class B and Class C shares.
The Plan allows the Fund to pay distribution fees for the sale and distribution
of these shares. It also allows the Fund to pay for services to shareholders of
Class A, Class B and Class C shares. Because these fees are paid out of the
Fund's assets on an ongoing basis, over time these fees will increase the cost
of your investment in these Classes and may cost you more than paying other
types of sales charges.


24

<PAGE>


FINANCIAL HIGHLIGHTS

The financial highlights table is intended to help you understand the Fund's
financial performance for the past 5 fiscal years of the Fund. Certain
information reflects financial results for a single Fund share. The total
returns in the table represent the rate an investor would have earned or lost
on an investment in the Fund (assuming reinvestment of all dividends and
distributions).


This information has been audited by PricewaterhouseCoopers LLP, independent
accountants, whose report, along with the Fund's financial statements, is
included in the annual report, which is available upon request.

<TABLE>
<CAPTION>
                                                                                                    FOR THE PERIOD
                                                          FOR THE                FOR THE            JULY 28, 1997*
                                                        YEAR ENDED             YEAR ENDED               THROUGH
                                                     DECEMBER 31, 1999      DECEMBER 31, 1998      DECEMBER 31, 1997
<S>                                               <C>                    <C>                    <C>
 CLASS A
 SELECTED PER-SHARE DATA:
 Net asset value, beginning of period                    $12.02                 $12.09                  $12.00
 Income (loss) from investment operations:
  Net investment income                                    0.58                   0.59                    0.25
  Net realized and unrealized gain (loss)                 (0.91)                  0.10                    0.14
                                                        --------               --------                 -----
 Total income (loss) from investment operations           (0.33)                  0.69                    0.39

 Less dividends and distributions from:
  Net investment income                                   (0.58)                 (0.59)                  (0.25)
  Net realized gain                                       (0.03)                 (0.17)                  (0.05)
                                                        --------               --------                 ------
 Total dividends and distributions                        (0.61)                 (0.76)                  (0.30)
 Net asset value, end of period                          $11.08                 $12.02                  $12.09
 TOTAL RETURN+                                            (2.82)%                 5.86%                   3.31%(1)

 RATIOS TO AVERAGE NET ASSETS:

 Expenses                                                  0.64%(4)(5)            0.74%(4)(5)             0.76%(2)(3)
 Net investment income                                     4.98%(5)               4.88%(5)                4.96%(2)

 SUPPLEMENTAL DATA:
 Net assets, end of period, in thousands                $17,198                $15,041                  $3,857
 Portfolio turnover rate                                     13%                    15%                     16%
</TABLE>


*     The date shares were first issued.
+     Does not reflect the deduction of sales charge. Calculated based on the
      net asset value as of the last business day of the period.
(1)   Not annualized.
(2)   Annualized.
(3)   Does not reflect the effect of expense offset of 0.02%.
(4)   Does not reflect the effect of expense offset of 0.01%.
(5)   Reflects overall Fund ratios for investment income and non-class specific
      expenses.


                                                                              25

<PAGE>


<TABLE>
<CAPTION>
                                                                                                    FOR THE PERIOD
                                                          FOR THE                FOR THE            JULY 28, 1997*
                                                        YEAR ENDED             YEAR ENDED               THROUGH
                                                     DECEMBER 31, 1999      DECEMBER 31, 1998      DECEMBER 31, 1997
<S>                                               <C>                    <C>                    <C>
 CLASS B
 SELECTED PER-SHARE DATA:
 Net asset value, beginning of period                      $12.07                $12.14                  $12.00
                                                          --------               --------               --------
 Income (loss) from investment operations:
  Net investment income                                      0.53                  0.55                    0.23
  Net realized and unrealized gain (loss)                   (0.91)                 0.10                    0.19
                                                          --------               --------               --------
 Total income (loss) from investment operations             (0.38)                 0.65                    0.42
                                                          --------               --------               --------
 Less dividends and distributions from:
  Net investment income                                     (0.53)                (0.55)                  (0.23)
  Net realized gain                                         (0.03)                (0.17)                  (0.05)
                                                          --------               --------               --------
 Total dividends and distributions                          (0.56)                (0.72)                  (0.28)
                                                          --------               --------               --------
 Net asset value, end of period                            $11.13                $12.07                  $12.14

 TOTAL RETURN+                                              (3.25)%                5.47%                   3.57%(1)

 RATIOS TO AVERAGE NET ASSETS:
 Expenses                                                    1.11%(4)(5)           1.10%(4)(5)             1.14%(2)(3)
 Net investment income                                       4.51%(5)              4.52%(5)                4.87%(2)

SUPPLEMENTAL DATA:
 Net assets, end of period, in thousands                  $139,786              $132,303                 $95,573
 Portfolio turnover rate                                       13%                   15%                     16%
</TABLE>


*     The date shares were first issued.
+     Does not reflect the deduction of sales charge. Calculated based on the
      net asset value as of the last business day of the period.
(1)   Not annualized.
(2)   Annualized.
(3)   Does not reflect the effect of expense offset of 0.02%.
(4)   Does not reflect the effect of expense offset of 0.01%.
(5)   Reflects overall Fund ratios for investment income and non-class specific
      expenses.

26


<PAGE>




<TABLE>
<CAPTION>
                                                                                               FOR THE PERIOD
                                                     FOR THE                FOR THE            JULY 28, 1997*
                                                   YEAR ENDED             YEAR ENDED               THROUGH
                                                DECEMBER 31, 1999      DECEMBER 31, 1998      DECEMBER 31, 1997
<S>                                          <C>                    <C>                    <C>
 CLASS C
 SELECTED PER-SHARE DATA:
 Net asset value, beginning of period                $12.04                $12.11                 $12.00
 Income (loss) from investment operations:
  Net investment income                                0.51                  0.53                   0.23
  Net realized and unrealized gain (loss)             (0.91)                 0.10                   0.16
                                                   --------              ---------              ---------
 Total income (loss) from investment
 operations                                           (0.40)                 0.63                   0.39
 Less dividends and distributions from:
  Net investment income                               (0.51)                (0.53)                 (0.23)
  Net realized gain                                   (0.03)                (0.17)                 (0.05)
                                                   --------              ---------              ---------
 Total dividends and distributions                    (0.54)                (0.70)                 (0.28)
 Net asset value, end of period                      $11.10                $12.04                 $12.11
 TOTAL RETURN+                                        (3.37)%                5.36%                  3.28%(1)
 RATIOS TO AVERAGE NET ASSETS:
 Expenses                                              1.21%(4)(5)           1.20%(4)(5)            1.20%(2)(3)
 Net investment income                                 4.41%(5)              4.34%(5)               4.41%(2)
 SUPPLEMENTAL DATA:
 Net assets, end of period, in thousands            $10,025                $7,599                 $2,953
 Portfolio turnover rate                                 13%                   15%                    16%
</TABLE>

*     The date shares were first issued.
+     Does not reflect the deduction of sales charge. Calculated based on the
      net asset value as of the last business day of the period.
(1)   Not annualized.
(2)   Annualized.
(3)   Does not reflect the effect of expense offset of 0.02%.
(4)   Does not reflect the effect of expense offset of 0.01%.
(5)   Reflects overall Fund ratios for investment income and non-class specific
      expenses.


                                                                              27

<PAGE>

<TABLE>
<CAPTION>

YEARS ENDED DECEMBER 31                                   1999
<S>                                                      <C>
CLASS D
SELECTED PER-SHARE DATA:
Net asset value, beginning of period                     $12.01
Income (loss) from investment operations:
  Net investment income                                    0.59
  Net realized and unrealized gain (loss)                 (0.91)
                                                         ------
Total income (loss) from investment operations            (0.32)
Less dividends and distributions from:
  Net investment income                                   (0.59)
  Net realized gain                                       (0.03)
                                                         ------
Total dividends and distributions                         (0.62)
Net asset value, end of period                           $11.07
TOTAL RETURN+                                             (2.71)%
RATIOS TO AVERAGE NET ASSETS:
Expenses                                                   0.51%(1)(2)
Net investment income                                      5.11%(2)
SUPPLEMENTAL DATA:
Net assets, end of period, in thousands                $853,216
Portfolio turnover rate                                      13%

<CAPTION>

YEARS ENDED DECEMBER 31                                    1998*                 1997*          1996           1995
<S>                                               <C>                       <C>            <C>            <C>
 CLASS D
 SELECTED PER-SHARE DATA:
 Net asset value, beginning of period                    $12.08                $11.77         $12.09         $11.01
 Income (loss) from investment operations:
  Net investment income                                    0.62                  0.63           0.65           0.67
  Net realized and unrealized gain (loss)                  0.10                  0.36          (0.24)          1.19
                                                        --------           ----------     ----------     ----------
 Total income (loss) from investment operations            0.72                  0.99           0.41           1.86
 Less dividends and distributions from:
  Net investment income                                   (0.62)                (0.63)         (0.65)         (0.67)
  Net realized gain                                       (0.17)                (0.05)         (0.08)         (0.11)
                                                       -----------           ----------     ----------     ----------
 Total dividends and distributions                        (0.79)                (0.68)         (0.73)         (0.78)
 Net asset value, end of period                          $12.01                $12.08         $11.77      $   12.09
 TOTAL RETURN+                                             6.11%                 8.73%          3.61%         17.37%
 RATIOS TO AVERAGE NET ASSETS:
 Expenses                                                  0.50%(1)(2)           0.49%          0.48%          0.48%
 Net investment income                                     5.12%(2)              5.34%          5.52%          5.76%
 SUPPLEMENTAL DATA:
 Net assets, end of period, in thousands             $1,023,246            $1,096,998     $1,190,034     $1,325,308
 Portfolio turnover rate                                     15%                   16%            18%            21%
</TABLE>


*     Prior to July 28, 1997, the Fund issued one class of shares. All shares
      of the Fund held prior to that date have been designated Class D shares.
+     Calculated based on the net asset value as of the last business day of
      the period.
(1)   Does not reflect the effect of expense offset of 0.01%.
(2)   Reflects overall Fund ratios for investment income and non-class specific
      expenses.

28

<PAGE>


MORGAN STANLEY DEAN WITTER
FAMILY OF FUNDS

The Morgan Stanley Dean Witter Family of Funds offers investors a wide range of
investment choices. Come on in and meet the family!
- --------------------------------------------------------------------------------

 GROWTH FUNDS


GROWTH FUNDS
Aggressive Equity Fund
American Opportunities Fund
Capital Growth Securities
Developing Growth Securities
Growth Fund
Market Leader Trust
Mid-Cap Equity Trust
Next Generation Trust
Small Cap Growth Fund
Special Value Fund
21st Century Trend Fund

THEME FUNDS
Financial Services Trust
Health Sciences Trust
Information Fund
Natural Resource Development Securities


GLOBAL/INTERNATIONAL FUNDS
Competitive Edge Fund -- "Best Ideas" Portfolio
European Growth Fund
Fund of Funds -- International Portfolio
International Fund
International SmallCap Fund
Japan Fund
Latin American Growth Fund
Pacific Growth Fund

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

 GROWTH & INCOME FUNDS


Balanced Growth Fund
Balanced Income Fund
Convertible Securities Trust
Dividend Growth Securities
Equity Fund
Fund of Funds -- Domestic Portfolio
Income Builder Fund
Mid-Cap Dividend Growth Securities
S&P 500 Index Fund
S&P 500 Select Fund
Strategist Fund

Total Market Index Fund
Total Return Trust
Value Fund
Value-Added Market Series/Equity Portfolio

THEME FUNDS
Real Estate Fund
Utilities Fund

GLOBAL FUNDS
Global Dividend Growth Securities
Global Utilities Fund

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

 INCOME FUNDS


GOVERNMENT INCOME FUNDS
Federal Securities Trust
Short-Term U.S. Treasury Trust
U.S. Government Securities Trust

DIVERSIFIED INCOME FUNDS
Diversified Income Trust

CORPORATE INCOME FUNDS
High Yield Securities
Intermediate Income Securities
Short-Term Bond Fund(NL)

GLOBAL INCOME FUNDS
North American Government Income Trust
World Wide Income Trust

TAX-FREE INCOME FUNDS
California Tax-Free Income Fund
Hawaii Municipal Trust(FSC)
Limited Term Municipal Trust(NL)
Multi-State Municipal Series Trust(FSC)
New York Tax-Free Income Fund
Tax-Exempt Securities Trust

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

 MONEY MARKET FUNDS


TAXABLE MONEY MARKET FUNDS
Liquid Asset Fund(MM)
U.S. Government Money Market Trust(MM)

TAX-FREE MONEY MARKET FUNDS
California Tax-Free Daily Income Trust(MM)
New York Municipal Money Market Trust(MM)
Tax-Free Daily Income Trust(MM)

There may be funds created after this Prospectus was published. Please consult
the inside back cover of a new Fund's Prospectus for its designation, e.g.,
Multi-Class Fund or Money Market Fund.

Unless otherwise noted, each listed Morgan Stanley Dean Witter Fund, except for
North American Government Income Trust and Short-Term U.S. Treasury Trust, is a
Multi-Class Fund. A Multi-Class Fund is a mutual fund offering multiple Classes
of shares. The other types of Funds are: NL -- No-Load (Mutual) Fund; MM --
Money Market Fund; FSC -- A mutual fund sold with a front-end sales charge and
a distribution (12b-1) fee.


<PAGE>


                                           PROSPECTUS - FEBRUARY 24, 2000

Additional information about the Fund's investments is available in the Fund's
Annual and Semi-Annual Reports to Shareholders. In the Fund's Annual Report, you
will find a discussion of the market conditions and investment strategies that
significantly affected the Fund's performance during its last fiscal year. The
Fund's Statement of Additional Information also provides additional information
about the Fund. The Statement of Additional Information is incorporated herein
by reference (legally is part of this Prospectus). For a free copy of any of
these documents, to request other information about the Fund, or to make
shareholder inquiries, please call:

                                 (800) 869-NEWS

You also may obtain information about the Fund by calling your Morgan Stanley
Dean Witter Financial Advisor or by visiting our Internet site at:

                          WWW.MSDW.COM/INDIVIDUAL/FUNDS

Information about the Fund (including the Statement of Additional Information)
can be viewed and copied at the Securities and Exchange Commission's Public
Reference Room in Washington, DC. Information about the Reference Room's
operations may be obtained by calling the SEC at (202) 942-8090. Reports and
other information about the Fund are available on the EDGAR Database on the
SEC's Internet site (www.sec.gov), and copies of this information may be
obtained, after paying a duplicating fee, by electronic request at the
following e-mail address: [email protected], or by writing the Public
Reference Section of the SEC, Washington, DC 20549-0102.


TICKER SYMBOLS:

  Class A:          TAXAX           Class C:          TAXCX
  Class B:          TAXBX           Class D:          TAXDX

(THE FUND'S INVESTMENT COMPANY ACT FILE NO. IS 811-2979)

Morgan Stanley Dean Witter


TAX-EXEMPT SECURITIES TRUST





[GRAPHIC OMITTED]




A MUTUAL FUND THAT SEEKS TO
PROVIDE A HIGH LEVEL OF CURRENT
INCOME EXEMPT FROM FEDERAL
INCOME TAX, CONSISTENT WITH
THE PRESERVATION OF CAPITAL


<PAGE>

         MORGAN STANLEY DEAN WITTER MULTI-STATE MUNICIPAL SERIES TRUST
                                MICHIGAN SERIES

                   PROXY FOR SPECIAL MEETING OF SHAREHOLDERS

                            TO BE HELD JUNE 22, 2000

     The undersigned shareholder of Michigan Series ("Michigan Series"), a
portfolio of Morgan Stanley Dean Witter Multi-State Municipal Series Trust,
does hereby appoint Barry Fink, Ronald E. Robison and Joseph J. McAlinden and
each of them, as attorneys-in-fact and proxies of the undersigned, each with
the full power of substitution, to attend the Special Meeting of Shareholders
of Michigan Series to be held on June 22, 2000, in Conference Room A,
Forty-Fourth Floor, Two World Trade Center, New York, New York at 10:00 A.M.,
New York time, and at all adjournments thereof and to vote the shares held in
the name of the undersigned on the record date for said meeting for the
Proposal specified on the reverse side hereof. Said attorneys-in-fact shall
vote in accordance with their best judgment as to any other matter.





                          (Continued on reverse side)

THIS PROXY IS SOLICITED ON BEHALF OF THE BOARD OF TRUSTEES. THIS PROXY WHEN
PROPERLY EXECUTED WILL BE VOTED IN THE MANNER DIRECTED HEREIN BY THE
UNDERSIGNED SHAREHOLDER. IF NO DIRECTION IS MADE, THIS PROXY WILL BE VOTED
"FOR" THE PROPOSAL SET FORTH ON THE REVERSE HEREOF AND AS RECOMMENDED BY THE
BOARD OF TRUSTEES.

      IMPORTANT--THIS PROXY MUST BE SIGNED AND DATED ON THE REVERSE SIDE.
<PAGE>

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


                                                            PLEASE MARK VOTES
AS TO VOTE BY MAIL, PLEASE COMPLETE AND RETURN THIS CARD
YOU ALSO MAY VOTE A PROXY BY TOUCH-TONE PHONE OR BY INTERNET IN THE EXAMPLE
USING
                                                                          X
(SEE ENCLOSED VOTING INFORMATION CARD FOR FURTHER INSTRUCTIONS) BLACK OR BLUE
                                                                 INK

TO VOTE A PROXY BY PHONE, call Toll-Free: 1-800-690-6903

TO VOTE A PROXY BY INTERNET, visit our Website(s): WWW/MSDWT.COM or
WWW.PROXYVOTE.COM

 FOR  AGAINST                                                         ABSTAIN




The Proposal:

Approval of the Agreement and Plan of
Reorganization, dated as of January 26, 2000, pursuant to which substantially
all of the assets of Michigan Series would be combined with those of Morgan
Stanley Dean Witter Tax-Exempt Securities Trust and shareholders of Michigan
Series would become shareholders of Morgan Stanley Dean Witter Tax-Exempt
Securities Trust receiving Class D shares in Morgan Stanley Dean Witter
Tax-Exempt Securities Trust with a value equal to the value of their holdings
in Michigan Series.


Please sign personally. If the shares are registered in more than one name,
each joint owner or each fiduciary should sign personally. Only authorized
officers should sign for corporations.

     Please make sure to sign and date this Proxy using black or blue ink.


               Date-----------------------------------------


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

               ---------------------------------------------
                       Shareholder sign in the box above

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

               ---------------------------------------------
                    Co-Owner (if any) sign in the box above

   -   -    PLEASE FOLD AND DETACH AT PERFORATION ALONG DOTTED LINES    -   --


         MORGAN STANLEY DEAN WITTER MULTI-STATE MUNICIPAL SERIES TRUST
                                MICHIGAN SERIES

                                   IMPORTANT

               USE ONE OF THE THREE EASY WAYS TO VOTE YOUR PROXY

 1. BY MAIL. PLEASE DATE, SIGN AND RETURN THE ABOVE PROXY CARD IN THE ENCLOSED
    POSTAGE PAID ENVELOPE.

 2. BY INTERNET. HAVE YOUR PROXY CARD AT HAND. GO TO THE "VOTE YOUR PROXY HERE"
    LINK ON THE WEBSITE WWW.MSDWT.COM OR WWW.PROXYVOTE.COM. ENTER YOUR 12
    DIGIT CONTROL NUMBER LOCATED ON THE PROXY CARD AND FOLLOW THE SIMPLE
    INSTRUCTIONS.

 3. BY TELEPHONE. HAVE YOUR PROXY CARD AT HAND. CALL 1-800-690-6903 ON A
    TOUCH-TONE PHONE. ENTER YOUR 12-DIGIT CONTROL NUMBER LOCATED ON THE PROXY
    CARD AND FOLLOW THE SIMPLE RECORDED INSTRUCTIONS.


00024

<PAGE>

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

MORGAN STANLEY DEAN WITTER FUNDS
- -------------------------------------------------------------------------------

     OFFERS TWO NEW WAYS TO VOTE YOUR PROXY
     24 HOURS A DAY, 7 DAYS A WEEK

     You can now vote your proxy in a matter of minutes with the ease and
     convenience of the Internet or the telephone. You may still vote by mail.
     But remember, if you are voting by Internet or telephone, do not mail the
     proxy.

     TO VOTE BY INTERNET:

     1. Read the enclosed Proxy Statement and have your Proxy Card available.
     2. Go to the "Proxy Voting" link on www.msdwt.com or to website
        www.proxyvote.com.
     3. Enter the 12-digit Control Number found on your Proxy Card.
     4. Follow the simple instructions.

     TO VOTE BY TELEPHONE:

     1. Read the enclosed Proxy Statement and have your Proxy Card available.
     2. Call toll-free 1-800-690-6903.
     3. Enter the 12-digit Control Number found on your Proxy Card.
     4. Follow the simple recorded instructions.

                                                  Your Proxy Vote is Important!
                                           Thank You for Submitting Your Proxy.

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




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