VAN KAMPEN AMERICAN CAPITAL U S GOVERNMENT TRUST FOR INCOME
497, 1998-09-29
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<PAGE>   1
 
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                  VAN KAMPEN U.S. GOVERNMENT TRUST FOR INCOME
- --------------------------------------------------------------------------------
 
    Van Kampen U.S. Government Trust for Income (the "Fund") is a diversified,
open-end management investment company, commonly known as a mutual fund. The
Fund's investment objective is to provide investors with a high level of current
income. The Fund seeks to achieve its investment objective by investing
primarily in debt securities issued or guaranteed by the U.S. Government, its
agencies or instrumentalities, including mortgage-related securities issued by
instrumentalities of the U.S. Government. In order to hedge against changes in
interest rates, the Fund may also purchase or sell options and engage in
transactions involving futures contracts and options on such contracts. The Fund
does not engage in an option writing program for the purpose of enhancing or
supporting its monthly distribution. See "Investment Practices" for more
information. There is no assurance that the Fund will achieve its investment
objective.
 
    The Fund's investment adviser is Van Kampen Asset Management Inc. (the
"Adviser"). This Prospectus sets forth certain information that a prospective
investor should know before investing in the Fund. Please read it carefully and
retain it for future reference. The address of the Fund is One Parkview Plaza,
Oakbrook Terrace, Illinois 60181, and its telephone number is (800) 421-5666.
 
                               ------------------
 
THESE SECURITIES HAVE NOT BEEN APPROVED OR DISAPPROVED BY THE SECURITIES AND
EXCHANGE COMMISSION OR ANY STATE REGULATORS NOR HAS THE COMMISSION OR ANY STATE
REGULATORS PASSED UPON THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY
REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
                               ------------------
 
    SHARES OF THE FUND ARE NOT DEPOSITS OR OBLIGATIONS OF, OR GUARANTEED OR
ENDORSED BY, ANY BANK OR DEPOSITORY INSTITUTION; FURTHER, SUCH SHARES ARE NOT
FEDERALLY INSURED BY THE FEDERAL DEPOSIT INSURANCE CORPORATION, THE FEDERAL
RESERVE BOARD OR ANY OTHER GOVERNMENT AGENCY. SHARES OF THE FUND INVOLVE
INVESTMENT RISKS, INCLUDING POSSIBLE LOSS OF PRINCIPAL.
 
    A Statement of Additional Information, dated January 28, 1998, containing
additional information about the Fund is hereby incorporated by reference in its
entirety into this Prospectus. A copy of the Statement of Additional Information
may be obtained without charge by calling (800) 421-5666 or for
Telecommunications Device for the Deaf at (800) 421-2833. The Statement of
Additional Information has been filed with the Securities and Exchange
Commission ("SEC") and is available along with other related materials at the
SEC's internet web site (http://www.sec.gov).
 
                           [VAN KAMPEN FUNDS LOGO]
 
         THIS PROSPECTUS IS DATED JANUARY 28, 1998, AS SUPPLEMENTED ON
               MARCH 9, 1998, JULY 14, 1998 AND OCTOBER 1, 1998.
<PAGE>   2
 
- --------------------------------------------------------------------------------
                               TABLE OF CONTENTS
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                                                              PAGE
                                                              ----
<S>                                                           <C>
Prospectus Summary..........................................    3
Shareholder Transaction Expenses............................    5
Annual Fund Operating Expenses and Example..................    6
Financial Highlights........................................    7
The Fund....................................................    9
Investment Objective and Policies...........................    9
Investment Practices........................................   13
Investment Advisory Services................................   16
Alternative Sales Arrangements..............................   17
Purchase of Shares..........................................   19
Shareholder Services........................................   25
Redemption of Shares........................................   28
Distribution and Service Plans..............................   29
Distributions from the Fund.................................   31
Tax Status..................................................   31
Fund Performance............................................   33
Description of Shares of the Fund...........................   35
Additional Information......................................   35
</TABLE>
 
  NO DEALER, SALESPERSON OR ANY OTHER PERSON HAS BEEN AUTHORIZED TO GIVE ANY
INFORMATION OR TO MAKE ANY REPRESENTATIONS, OTHER THAN THOSE CONTAINED IN THIS
PROSPECTUS, IN CONNECTION WITH THE OFFER CONTAINED IN THIS PROSPECTUS AND, IF
GIVEN OR MADE, SUCH OTHER INFORMATION OR REPRESENTATIONS MUST NOT BE RELIED UPON
AS HAVING BEEN AUTHORIZED BY THE FUND, THE ADVISER OR THE DISTRIBUTOR. THIS
PROSPECTUS DOES NOT CONSTITUTE AN OFFER BY THE FUND OR BY THE DISTRIBUTOR TO
SELL OR A SOLICITATION OF AN OFFER TO BUY ANY OF THE SECURITIES OFFERED HEREBY
IN ANY JURISDICTION TO ANY PERSON TO WHOM IT IS UNLAWFUL FOR THE FUND TO MAKE
SUCH AN OFFER IN SUCH JURISDICTION.
 
                                        2
<PAGE>   3
 
- --------------------------------------------------------------------------------
                               PROSPECTUS SUMMARY
- --------------------------------------------------------------------------------
 
THE FUND.  Van Kampen U.S. Government Trust for Income (the "Fund") is a
diversified, open-end management investment company organized as a Delaware
business trust.
 
MINIMUM PURCHASE.  $500 minimum initial investment for each class of shares and
$25 minimum for each subsequent investment for each class of shares (or less as
described under "Purchase of Shares").
 
INVESTMENT OBJECTIVE.  The investment objective of the Fund is to provide a high
level of current income. There is no assurance that the Fund will achieve its
investment objective. See "Investment Objective and Policies."
 
INVESTMENT POLICY.  The Fund seeks to achieve its investment objective by
investing primarily in debt securities issued or guaranteed by the U.S.
Government, its agencies or instrumentalities, including mortgage-related
securities issued by instrumentalities of the U.S. Government. Under normal
circumstances, at least 65% of the total assets of the Fund are invested in such
securities and in repurchase agreements fully collateralized by U.S. Government
securities. The Fund may invest up to 35% of its total assets in high quality
debt securities issued by foreign governments and their political subdivisions,
agencies and instrumentalities and certain debt securities which are not U.S.
Government securities. The Fund may lend portfolio securities. The Fund may sell
(write) and purchase call and put options, and may purchase and sell interest
rate futures contracts and options on such contracts so long as such
transactions are entered into for bona fide hedging purposes. The Fund may
purchase or sell debt securities on a forward commitment basis and enter into
interest rate swaps and may purchase or sell interest rate caps, floors and
collars.
 
INVESTMENT RESULTS.  The investment results of the Fund are shown in the table
of "Financial Highlights."
 
ALTERNATIVE SALES ARRANGEMENTS.  The Fund offers three classes of shares to the
public, each with its own sales charge structure: Class A shares, Class B shares
and Class C shares. Each class has distinct advantages and disadvantages for
different investors, and investors may choose the class of shares that best
suits their circumstances and objectives. Each class of shares represents an
interest in the same portfolio of investments of the Fund. See "Alternative
Sales Arrangements." For information on redeeming shares see "Redemption of
Shares."
 
  Class A Shares.  Class A shares are offered at net asset value per share plus
a maximum initial sales charge of 4.75% of the offering price (4.99% of the net
amount invested), reduced on investments of $100,000 or more. Investments of $1
million or more are not subject to any sales charge at the time of purchase, but
a contingent deferred sales charge ("CDSC") of 1.00% may be imposed on
redemptions made within one year of the purchase. Class A shares are subject to
an annual service fee of up to 0.25% of its average daily net assets
attributable to such class of shares. See "Purchase of Shares -- Class A Shares"
and "Distribution and Service Plans."
 
  Class B Shares.  Class B shares are offered at net asset value per share and
are subject to a maximum CDSC of 4.00% on redemptions made within the first or
second year after purchase and declining thereafter to 0.00% after the fifth
year. See "Redemption of Shares." Class B shares are subject to a combined
annual distribution fee and service fee of up to 1.00% of the Fund's average
daily net assets attributable to such class of shares. See "Purchase of
Shares -- Class B Shares" and "Distribution and Service Plans." Class B shares
convert automatically to Class A shares eight years after the end of the
calendar month in which the shareholder's order to purchase was accepted. See
"Alternative Sales Arrangements -- Conversion Feature."
 
  Class C Shares.  Class C shares are offered at net asset value per share and
are subject to a CDSC of 1.00% on redemptions made within one year of purchase.
See "Redemption of Shares." Class C shares are subject to a combined annual
distribution fee and service fee of up to 1.00% of the Fund's average daily net
assets attributable to such class of shares. See "Purchase of Shares -- Class C
Shares" and "Distribution and Service Plans."
 
INVESTMENT ADVISER.  Van Kampen Asset Management Inc. (the "Adviser") is the
Fund's investment adviser.
 
DISTRIBUTOR.  Van Kampen Funds Inc. (the "Distributor") distributes the Fund's
shares.
 
RISK FACTORS.  The market prices of debt securities, including U.S. Government
securities, generally fluctuate with changes in interest rates so that the
Fund's net asset value can be expected to decrease as interest rates rise. As
interest rates fall, increases in the Fund's net asset value may be limited by
investments in mortgage related securities and by the
 
                                        3
<PAGE>   4
 
sale of options. No assurance can be given as to the actual maturity of a
mortgage-related security because the mortgage loans underlying the security may
be prepaid by the obligor. Depending on market conditions, the Fund may be able
to reinvest pre-payments passed through to it only at a lower yielding
investment rate. Varying economic and market conditions may affect the value of,
and yields on, debt securities owned by the Fund. The Fund may also purchase or
sell debt securities on a forward commitment basis, purchase or sell options and
engage in transactions involving interest rate futures contracts and options on
such contracts, and may lend its portfolio securities. The Fund may enter into
interest rate swaps and may purchase or sell interest rate caps, floors and
collars. Each of such activities may subject the Fund to additional risks.
Shares of the Fund are not insured or guaranteed by the U.S. Government, its
agencies or instrumentalities or by any other person or entity. See "Investment
Objective and Policies" and "Investment Practices".
 
DISTRIBUTIONS FROM THE FUND.  Dividends from net investment income are declared
daily and distributed monthly. Any short-term or long-term capital gains are
distributed at least annually. The Fund does not engage in an option writing
program for the purpose of enhancing or supporting its monthly distribution. All
dividends and distributions are automatically reinvested in shares of the Fund
at net asset value per share (without sales charge) unless payment in cash is
requested. A portion of the dividends and distributions paid may constitute a
return of capital for federal income tax purposes. See "Distributions from the
Fund."
 
  The foregoing is qualified in its entirety by reference to the more detailed
              information appearing elsewhere in this Prospectus.
 
                                        4
<PAGE>   5
 
- --------------------------------------------------------------------------------
SHAREHOLDER TRANSACTION EXPENSES
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                                                              CLASS A      CLASS B        CLASS C
                                                              SHARES        SHARES         SHARES
                                                              -------      -------        -------
<S>                                                           <C>        <C>            <C>
Maximum sales charge imposed on purchases (as a percentage
  of offering price)........................................   4.75%(1)      None           None
Maximum sales charge imposed on reinvested dividends (as a
  percentage of offering price).............................    None         None           None
Deferred sales charge (as a percentage of the lesser of                      Year           Year
  original purchase price or redemption proceeds)...........    None(2)    1--4.00%       1--1.00%
                                                                             Year
                                                                           2--4.00%     After--None
                                                                             Year
                                                                           3--3.00%
                                                                             Year
                                                                           4--2.50%
                                                                             Year
                                                                           5--1.50%
                                                                         After--None
Redemption fees (as a percentage of amount redeemed)........    None         None           None
Exchange fee................................................    None         None           None
</TABLE>
 
- --------------------------------------------------------------------------------
(1) Reduced for purchases of $100,000 and over. See "Purchase of Shares -- Class
    A Shares."
 
(2) Investments of $1 million or more are not subject to any sales charge at the
    time of purchase, but a CDSC of 1.00% may be imposed on redemptions made
    within one year of the purchase. See "Purchase of Shares -- Class A Shares."
 
                                        5
<PAGE>   6
 
- --------------------------------------------------------------------------------
ANNUAL FUND OPERATING EXPENSES AND EXAMPLE
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                                                              CLASS A   CLASS B   CLASS C
                                                              SHARES    SHARES    SHARES
                                                              -------   -------   -------
<S>                                                           <C>       <C>       <C>
Management Fees (as a percentage of average daily net
  assets)...................................................   0.60%     0.60%     0.60%
12b-1 Fees (as a percentage of average daily net
  assets)(1)................................................   0.25%     1.00%(2)  1.00%(2)
Other Expenses (as a percentage of average daily net
  assets)...................................................   0.33%     0.34%     0.34%
Total Expenses (as a percentage of average daily net
  assets)...................................................   1.18%     1.94%     1.94%
</TABLE>
 
- --------------------------------------------------------------------------------
(1) Class A shares are subject to an annual service fee of up to 0.25% of the
    average daily net assets attributable to such class of shares. Class B
    shares and Class C shares are each subject to a combined annual distribution
    and service fee of up to 1.00% of the average daily net assets attributable
    to such class of shares. See "Distribution and Service Plans."
 
(2) Long-term shareholders may pay more than the economic equivalent of the
    maximum front-end sales charges permitted by the rules of the National
    Association of Securities Dealers, Inc.
 
<TABLE>
<CAPTION>
                                                                ONE      THREE     FIVE       TEN
                                                               YEAR      YEARS     YEARS     YEARS
                          EXAMPLE:                             ----      -----     -----     -----
<S>                                                           <C>       <C>       <C>       <C>
You would pay the following expenses on a $1,000 investment,
  assuming (i) an operating expense ratio of 1.18% for Class
  A shares, 1.94% for Class B shares and 1.94% for Class C
  shares, (ii) a 5.00% annual return and (iii) redemption at
  the end of each time period:
    Class A shares..........................................    $59       $83      $109      $184
    Class B shares..........................................    $60       $91      $120      $207*
    Class C shares..........................................    $30       $61      $105      $226
An investor would pay the following expenses on the same
  $1,000 investment assuming no redemption at the end of
  each time period:
    Class A shares..........................................    $59       $83      $109      $184
    Class B shares..........................................    $20       $61      $105      $207*
    Class C shares..........................................    $20       $61      $105      $226
</TABLE>
 
- --------------------------------------------------------------------------------
* Based on conversion to Class A shares after eight years.
 
  The purpose of the foregoing table is to assist an investor in understanding
the various costs and expenses that an investor in the Fund will bear directly
or indirectly. The "Example" reflects expenses based on the "Annual Fund
Operating Expenses" table as shown above carried out to future years and is
included to provide a means for the investor to compare expense levels of funds
with different fee structures over varying investment periods. To facilitate
such comparison, all funds are required by the SEC to utilize a 5.00% annual
return assumption. The ten year amount with respect to Class B shares of the
Fund reflects the lower aggregate 12b-1 and service fees applicable to such
shares after conversion to Class A shares. Class B shares acquired through the
exchange privilege are subject to the CDSC schedule relating to the Class B
shares of the fund from which the purchase of Class B shares was originally
made. Accordingly, future expenses as projected could be higher than those
determined in the above table if the investor's Class B shares were exchanged
from a fund with a higher CDSC. THE INFORMATION CONTAINED IN THE ABOVE TABLE
SHOULD NOT BE CONSIDERED A REPRESENTATION OF PAST OR FUTURE EXPENSES AND ACTUAL
EXPENSES MAY BE GREATER OR LESS THAN THOSE SHOWN. For a more complete
description of such costs and expenses, see "Purchase of Shares," "Investment
Advisory Services," "Redemption of Shares" and "Distribution and Service Plans."
 
                                        6
<PAGE>   7
- --------------------------------------------------------------------------------
FINANCIAL HIGHLIGHTS (Selected data for a share of beneficial interest
                     outstanding throughout each of the periods indicated)
- --------------------------------------------------------------------------------
 
  The following financial highlights have been audited by PricewaterhouseCoopers
LLP, independent accountants, whose report thereon was unqualified. The most
recent annual report (which contains the financial highlights for the last five
fiscal periods) is included in the Statement of Additional Information and may
be obtained by shareholders without charge by calling the telephone number on
the cover of this Prospectus. This information should be read in conjunction
with the financial statements and notes thereto included in the Statement of
Additional Information.
 
<TABLE>
<CAPTION>
                                                                                       CLASS A SHARES
                                                                ------------------------------------------------------------
                                                                                                             OCTOBER 6, 1992
                                                                                                              (COMMENCEMENT
                                                                                                              OF INVESTMENT
                                                                         YEAR ENDED SEPTEMBER 30             OPERATIONS) TO
                                                                -----------------------------------------     SEPTEMBER 30,
                                                                 1997       1996       1995        1994          1993(a)
                                                                -------    -------    -------    --------    ---------------
<S>                                                             <C>        <C>        <C>        <C>         <C>
Net Asset Value, Beginning of the Period....................     $8.108      $8.38      $8.17       $9.26          $9.43
                                                                -------    -------    -------    --------       --------
 Net Investment Income......................................       .567       .565        .63         .67            .81
 Net Realized and Unrealized Gain/Loss......................       .073      (.274)       .23     (1.0085)        (.1795)
                                                                -------    -------    -------    --------       --------
Total from Investment Operations............................       .640       .291        .86      (.3385)         .6305
                                                                -------    -------    -------    --------       --------
Less Distributions from:
 Net Investment Income......................................      (.555)     (.563)     (.645)      (.674)        (.8005)
 Net Realized Gain..........................................         --         --      (.005)     (.0775)            --
                                                                -------    -------    -------    --------       --------
Total Distributions.........................................      (.555)     (.563)      (.65)     (.7515)        (.8005)
                                                                -------    -------    -------    --------       --------
Net Asset Value, End of the Period..........................     $8.193     $8.108      $8.38       $8.17          $9.26
                                                                =======    =======    =======    ========       ========
Total Return(b).............................................      8.09%      3.57%     10.97%      (3.82%)       8.07%(c)
Net Assets at End of the Period (In millions)...............      $38.3      $45.2      $70.2       $75.3          $92.4
Ratio of Expenses to Average Net Assets(d)..................      1.18%      1.13%      1.09%       1.07%          1.07%
Ratio of Net Investment Income to Average Net Assets(d).....      6.95%      6.83%      7.67%       7.89%          8.71%
Portfolio Turnover Rate.....................................        82%       282%       262%        122%          281%*
</TABLE>
 
                               (Table and footnotes continued on following page)
 
                                        7
<PAGE>   8
- --------------------------------------------------------------------------------
FINANCIAL HIGHLIGHTS -- (CONTINUED)
- --------------------------------------------------------------------------------
<TABLE>
<CAPTION>
                                                         CLASS B SHARES                                 CLASS C SHARES
                                     ------------------------------------------------------   -----------------------------------
                                                                           OCTOBER 6, 1992
                                                                           COMMENCEMENT OF
                                                                              INVESTMENT
                                           YEAR ENDED SEPTEMBER 30          OPERATIONS) TO          YEAR ENDED SEPTEMBER 30
                                     -----------------------------------    SEPTEMBER 30,     -----------------------------------
                                      1997     1996     1995      1994         1993(a)         1997     1996     1995      1994
                                     ------   ------   -------   -------   ----------------   ------   ------   -------   -------
<S>                                  <C>      <C>      <C>       <C>       <C>                <C>      <C>      <C>       <C>
Net Asset Value, Beginning of the
 Period............................  $8.104    $8.38     $8.17     $9.26         $9.43        $8.104    $8.38     $8.17     $9.25
                                     ------   ------   -------   -------       -------        ------   ------   -------   -------
 Net Investment Income.............    .505     .504       .57       .61           .70          .503     .502       .57       .63
 Net Realized and Unrealized
   Gain/Loss.......................    .073    (.277)     .228   (1.0205)       (.1475)         .074    (.275)     .228   (1.0305)
                                     ------   ------   -------   -------       -------        ------   ------   -------   -------
Total from Investment Operations...    .578     .277      .798    (.4105)        .5525          .577     .227      .798    (.4005)
                                     ------   ------   -------   -------       -------        ------   ------   -------   -------
Less Distributions from:
 Net Investment Income.............   (.495)   (.503)    (.583)    (.602)       (.7225)        (.495)   (.503)    (.583)    (.602)
 Net Realized Gain.................      --       --     (.005)   (.0775)           --            --     --       (.005)   (.0775)
                                     ------   ------   -------   -------       -------        ------   ------   -------   -------
Total Distributions................   (.495)   (.503)    (.588)   (.6795)       (.7225)        (.495)   (.503)    (.588)   (.6795)
                                     ------   ------   -------   -------       -------        ------   ------   -------   -------
Net Asset Value, End of the
 Period............................  $8.187   $8.104     $8.38     $8.17         $9.26        $8.186   $8.104     $8.38     $8.17
                                     ======   ======   =======   =======       =======        ======   ======   =======   =======
Total Return(b)....................   7.43%    2.70%    10.14%    (4.61%)      7.24%(c)        7.43%    2.70%    10.14%    (4.51%)
Net Assets at End of the Period (In
 millions).........................  121.7%   $150.8    $200.2    $226.7        $242.8         $13.7    $18.6     $28.1     $37.5
Ratio of Expenses to Average Net
 Assets(d).........................   1.94%    1.89%     1.85%     1.82%         1.81%         1.94%    1.89%     1.85%     1.82%
Ratio of Net Investment Income to
 Average Net Assets(d).............   6.20%    6.08%     6.92%     7.11%         7.70%         6.20%    6.08%     6.94%     7.08%
Portfolio Turnover Rate............     82%     282%      262%      122%          281%*          82%     282%      262%      122%
 
<CAPTION>
                                      CLASS C SHARES
                                     ----------------
                                      APRIL 12, 1993
                                     (COMMENCEMENT OF
                                     DISTRIBUTION) TO
                                      SEPTEMBER 30,
                                         1993(a)
                                     ----------------
<S>                                  <C>
Net Asset Value, Beginning of the
 Period............................        $9.41
                                         -------
 Net Investment Income.............          .33
 Net Realized and Unrealized
   Gain/Loss.......................       (.1561)
                                         -------
Total from Investment Operations...        .1739
                                         -------
Less Distributions from:
 Net Investment Income.............       (.3339)
 Net Realized Gain.................           --
                                         -------
Total Distributions................       (.3339)
                                         -------
Net Asset Value, End of the
 Period............................        $9.25
                                         =======
Total Return(b)....................        2.10%*
Net Assets at End of the Period (In
 millions).........................        $37.8
Ratio of Expenses to Average Net
 Assets(d).........................        1.76%
Ratio of Net Investment Income to
 Average Net Assets(d).............        7.26%
Portfolio Turnover Rate............         281%*
</TABLE>
 
- ------------
 
*Non-Annualized
(a) Based on average month-end shares outstanding.
(b) Total return is based upon net asset value which does not include payment of
    the maximum sales charge or contingent deferred sales charge.
(c) Total return from November 2, 1992 (date the Fund's investment strategy was
    implemented) through September 30, 1993 without annualization.
(d) For the year ended September 30, 1997, the impact of expenses reimbursed by
    the Adviser was less than 0.01% of average net assets. For the period ended
    September 30, 1993, the ratios of expenses and net investment income to
    average net assets for Class A shares would have been 1.15% and 8.64%,
    respectively, had the Adviser not reimbursed certain expenses of the Fund.
    For the period ended September 30, 1993, the ratios of expenses and net
    investment income to average net assets for Class B shares would have been
    1.89% and 7.62%, respectively, had the Adviser not reimbursed certain
    expenses of the Fund. For the period ended September 30, 1993, the ratios of
    expenses and net investment income to average net assets for Class C shares
    would have been 1.83% and 7.18%, respectively, had the Adviser not
    reimbursed certain expenses of the Fund.
 
                                        8
<PAGE>   9
 
- --------------------------------------------------------------------------------
THE FUND
- --------------------------------------------------------------------------------
 
  The Fund is a diversified, open-end management investment company, commonly
known as a mutual fund. A mutual fund provides, for those who have similar
investment goals, a practical and convenient way to invest in a diversified
portfolio of securities by combining their resources in an effort to achieve
such goals.
 
  Van Kampen Asset Management Inc. (the "Adviser") provides investment advisory
and administrative services to the Fund. The Adviser and its affiliates also act
as investment adviser to other mutual funds distributed by Van Kampen Funds Inc.
(the "Distributor"). To obtain prospectuses and other information on any of
these other funds, please call the telephone number on the cover page of the
Prospectus.
 
- --------------------------------------------------------------------------------
INVESTMENT OBJECTIVE AND POLICIES
- --------------------------------------------------------------------------------
 
  GENERAL. The investment objective of the Fund is to seek to provide investors
with a high level of current income. The Fund seeks to achieve its objective by
investing primarily in debt securities issued or guaranteed by the U.S.
Government, its agencies or instrumentalities, including mortgage-related
securities issued or guaranteed by instrumentalities of the U.S. Government.
Under normal circumstances, at least 65% of the total assets of the Fund are
invested in such securities and in repurchase agreements fully collateralized by
U.S. Government securities. The Fund may invest up to 35% of its total assets in
high quality debt securities issued by foreign governments and their political
subdivisions, agencies and instrumentalities, certain debt securities which are
not U.S. Government securities but which are rated at the time of purchase
within the two highest grades assigned by Moody's Investors Service, Inc. or
Standard and Poor's Ratings Group or in any non-rated debt security considered
by the Adviser to be of comparable quality, and supranational issues. The Fund
may lend portfolio securities on a fully collateralized basis. See "Investment
Practices -- Lending of Securities" herein. In order to hedge against changes in
interest rates, the Fund may purchase or sell options and engage in transactions
involving futures contracts and options on such contracts and Eurodollar
instruments. See "Investment Practices -- Using Options, Futures Contracts and
Related Options and Eurodollar Instruments" herein, and the Statement of
Additional Information for discussion of options, futures contracts and related
options. The Fund may also purchase or sell debt securities on a forward
commitment basis and enter into interest rate swaps and may purchase or sell
interest rate caps, floors and collars. See "Investment Practices -- Forward
Commitments and Interest Rate Transactions" herein. Shares of the Fund are not
insured or guaranteed by the U.S. Government, its agencies or instrumentalities
or by any other person or entity. There is no assurance that the Fund will
achieve its investment objective.
 
  The prices of debt securities generally vary inversely with interest rates. If
interest rates rise, debt security prices generally fall; if interest rates
fall, debt security prices generally rise. Debt securities with longer
maturities generally offer higher yields than debt securities with shorter
maturities assuming all other factors, including credit quality, being equal.
For a given change in interest rates, the market price of longer-maturity debt
securities generally fluctuate more than the market price of shorter-maturity
debt securities. This potential for a decline in prices of debt securities due
to rising interest rates is referred to herein as "market risk."
 
  While the Fund has no policy limiting the maturities of the debt securities in
which it may invest, the Adviser seeks to moderate market risk by generally
maintaining a portfolio duration within a range of two to six years. Duration is
a measure of the expected life of a debt security that was developed as an
alternative to the concept of "term to maturity." Duration incorporates a debt
security's yield, coupon interest payments, final maturity and call features
into one measure. Traditionally a debt security's "term to maturity" has been
used as a proxy for the sensitivity of the security's price to changes in
interest rates (which is the "interest rate risk" or "price volatility" of the
security). However, "term to maturity" measures only the time until a debt
security provides its final payment taking no account of the pattern of the
security's payments of interest or principal prior to maturity. Duration is a
measure of the expected life of a debt security on a present value basis
expressed in years. It measures the length of the time interval between the
present and the time when the interest and principal payments are scheduled (or
in the case of a callable bond, expected to be received), weighing them by the
present value of the cash to be received at each future point in time. For any
debt security with interest payments occurring prior to the payment of
principal, duration is always less than maturity, and for zero coupon issues,
duration and term to maturity are equal. In general, the lower the coupon rate
of interest or the longer the maturity,
 
                                        9
<PAGE>   10
 
or the lower the yield-to-maturity of a debt security, the longer its duration;
conversely, the higher the coupon rate of interest, the shorter the maturity or
the higher the yield-to-maturity of a debt security, the shorter its duration.
 
  There are some situations where even the standard duration calculation does
not properly reflect the interest rate exposure of a security. For example,
floating and variable rate securities often have final maturities of ten or more
years; however, their interest rate exposure corresponds to the frequency of the
coupon reset. Another example where the interest rate exposure is not properly
captured by duration is the case of mortgage pass-through securities. The stated
final maturity of such securities is generally 30 years, but current prepayment
rates are more critical in determining the securities' interest rate exposure.
In these and other similar situations, the Adviser will use more sophisticated
analytical techniques that incorporate the economic life of a security into the
determination of its interest rate exposure.
 
  The Fund may purchase debt securities at a premium over the principal or face
value in order to obtain higher current income. The amount of any premium
declines during the term of the security to zero at maturity. Such decline
generally is reflected in the market price of the security and thus in the
Fund's net asset value. Any such decline is realized for accounting purposes as
a capital loss at maturity or upon resale. Prior to maturity or resale, such
decline in value could be offset, in whole or part, or increased by changes in
the value of the security due to changes in interest rate levels.
 
  The Fund may purchase or sell options and engage in transactions involving
interest rate futures contracts and options on such contracts but only for bona
fide hedging purposes. By using such securities, the Fund seeks to limit its
exposure to adverse interest rate changes, but the Fund also reduces its
potential for capital appreciation if interest rates decline. The purchase and
sale of such securities may result in a higher portfolio turnover rate than if
the Fund had not purchased or sold such securities. See "Investment
Practices -- Using Options, Futures Contracts and Related Options" and the
Statement of Additional Information for discussion of options, futures contracts
and related options.
 
  The investment objective of the Fund cannot be changed without shareholder
approval; however, the investment policies set forth in this section of the
Prospectus may be changed by the Trustees of the Fund without shareholder
approval.
 
  An investment in the Fund may not be appropriate for all investors. The Fund
is not intended to be a complete investment program, and investors should
consider their long-term investment goals and financial needs when making an
investment decision with respect to the Fund. An investment in the Fund is
intended to be a long-term investment, and should not be used as a trading
vehicle.
 
  U.S. GOVERNMENT SECURITIES. Securities issued or guaranteed by the U.S.
Government, its agencies or instrumentalities include: (1) U.S. Treasury
obligations, which differ in their interest rates, maturities and times of
issuance: U.S. Treasury bills (maturity of one year or less), U.S. Treasury
notes (maturity of one to ten years), and U.S. Treasury bonds (generally
maturities of greater than ten years), including the principal components or the
interest components issued by the U.S. Government under the Separate Trading of
Registered Interest and Principal of Securities program (i.e., "STRIPS"), all of
which are backed by the full faith and credit of the United States; and (2)
obligations issued or guaranteed by U.S. Government agencies or
instrumentalities, including government guaranteed mortgage-related securities,
some of which are backed by the full faith and credit of the U.S. Treasury, some
of which are supported by the right of the issuer to borrow from the U.S.
Government and some of which are backed only by the credit of the issuer itself
(as described below).
 
  U.S. Government securities include obligations issued or guaranteed by the
Government National Mortgage Association ("GNMA"), the Federal National Mortgage
Association ("FNMA") and the Federal Home Loan Mortgage Corporation ("FHLMC").
GNMA is a wholly-owned corporate instrumentality of the United States whose
securities and guarantees are backed by the full faith and credit of the United
States. FNMA, a federally chartered and privately-owned corporation, and FHLMC,
a federal corporation, are instrumentalities of the United States. The
securities and guarantees of FNMA and FHLMC are not backed, directly or
indirectly, by the full faith and credit of the United States. Although the
Secretary of the Treasury of the United States has discretionary authority to
lend amounts to FNMA up to certain specified limits, neither the United States
nor any agency thereof is obligated to finance FNMA's or FHLMC's operations or
to assist FNMA or FHLMC in any other manner. Securities of GNMA, FNMA and FHLMC
may include, but are not limited to, collateralized mortgage obligations
("CMOs") and real estate mortgage investment conduits ("REMICs") which are
described below under "Mortgage-Related Securities."
 
  MORTGAGE-RELATED SECURITIES. Mortgage loans made by banks, savings and loan
institutions, and other lenders are often assembled into pools. Interests in
such pools may then be issued by private entities or also may be issued or
guaranteed by
                                       10
<PAGE>   11
 
an agency or instrumentality of the U.S. Government. Interests in such pools are
what this Prospectus calls "Mortgage-Related Securities."
 
  Mortgage-Related Securities are characterized by monthly payments to the
holder, reflecting the underlying monthly payments made by the borrowers who
received the mortgage loans less fees paid to the guarantor and the servicer of
such mortgage loans. The payments to the holders of Mortgage-Related Securities
(such as the Fund), like the payments on the underlying mortgage loans,
represent both principal and interest. Although the underlying mortgage loans
are for specified periods of time, such as 20 or 30 years, the borrowers can,
and typically do, pay them off sooner. Thus, the holders of Mortgage-Related
Securities frequently receive prepayments of principal, in addition to the
principal which is part of the regular monthly payment. A borrower is more
likely to prepay a mortgage which bears a relatively high rate of interest. This
means that in times of declining interest rates, some of the Fund's higher
yielding securities might be converted to cash, and the Fund will be forced to
accept lower interest rates when that cash is used to purchase additional
securities. The increased likelihood of prepayment when interest rates decline
also limits market price appreciation of mortgage-related securities. If the
Fund buys mortgage-related securities at a premium, mortgage foreclosures or
mortgage prepayments may result in a loss to the Fund of up to the amount of the
premium paid since only timely payment of principal and interest is guaranteed.
 
  The Fund may invest in private Mortgage-Related Securities ("Private
Pass-Throughs") as opposed to Mortgage-Related Securities issued or guaranteed
by GNMA, FNMA, and FHLMC only if such Private Pass-Throughs are rated at the
time of purchase in the two highest grades by a nationally-recognized rating
agency or in any non-rated debt security considered by the Adviser to be of
comparable quality.
 
  CMOs are debt obligations collateralized by mortgage loans or Mortgage-Related
Securities. CMOs may be issued by agencies or instrumentalities of the U.S.
Government, or by private originators of, or investors in, mortgage loans,
including savings and loan associations, mortgage bankers, commercial banks,
investment banks and special purpose subsidiaries of the foregoing. An issuer of
CMOs may elect to be treated, for federal income tax purposes, as a REMIC. An
issuer of CMOs issued after 1991 must elect to be treated as a REMIC or it will
be taxable as a corporation under rules regarding taxable mortgage pools. CMOs
are issued in a number of classes or series with different maturities. The
classes or series are retired in sequence as the underlying mortgages are
repaid. Prepayment may shorten the stated maturity of the obligation and can
result in a loss of premium, if any has been paid. Certain of these securities
may have variable or floating interest rates and others may be stripped
(securities which provide only the principal or interest feature of the
underlying security).
 
  CMOs and REMICs issued by private entities are not government securities and
are not directly guaranteed by any government agency. They are secured by the
underlying collateral of the private issuer. The Fund will treat such privately
issued securities as U.S. Government securities only if they are 100%
collateralized at the time of issuance by securities issued or guaranteed by the
U.S. Government, its agencies or instrumentalities. The Fund intends to invest
in privately issued CMOs and REMICs only if they are rated at the time of
purchase in the two highest grades by a nationally-recognized rating agency.
 
  Additional information regarding Mortgage-Related Securities, CMOs and REMICs
is contained in the Fund's Statement of Additional Information.
 
  ZERO COUPON AND OTHER STRIPPED SECURITIES. The Fund may also invest in the
interest only or principal only components of debt securities described above.
This includes "zero coupon" Treasury securities and stripped securities.
 
  The Fund may invest in "zero coupon" Treasury securities which are U.S.
Treasury bills, notes and bonds which have been stripped of their unmatured
interest coupons and receipts or certificates representing interest on such
stripped debt obligations and coupons. A "zero coupon" security pays no interest
in cash to its holder during its life although interest is accrued during that
period. Its value to an investor consists of the difference between its face
value at the time of maturity and the price for which it was acquired, which is
generally an amount significantly less than its face value (sometimes referred
to as a "deep discount" price).
 
  Currently the principal U.S. Treasury security issued without coupons is the
Treasury bill. The Treasury also has wire transferable "zero coupon" Treasury
securities available. In the last few years a number of banks and brokerage
firms have separated ("stripped") the principal portions from the coupon
portions of the U.S. Treasury bonds and notes and sold them separately in the
form of receipts or certificates representing undivided interests in these
instruments (which
                                       11
<PAGE>   12
 
instruments are generally held by a bank in a custodial or trust account). Such
custodial receipts or certificates are not considered by the Fund to be U.S.
Government securities.
 
  "Zero coupon" Treasury securities do not entitle the holder to any periodic
payments of interest prior to maturity. Accordingly, such securities usually
trade at a deep discount from their face or par value and will be subject to
greater fluctuations of market value in response to changing interest rates than
debt obligations of comparable maturities which make periodic distributions of
interest. On the other hand, because there are no periodic interest payments to
be reinvested prior to maturity, "zero coupon" securities eliminate the
reinvestment risk and lock in a rate of return to maturity. Current federal tax
law requires that a holder (such as the Fund) of a "zero coupon" security accrue
a portion of the discount at which the security was purchased as income each
year even though the Fund received no interest payment in cash on the security
during the year. In order to generate sufficient cash to make distributions of
such income, the Fund may have to dispose of securities that it would otherwise
continue to hold, which, in some cases may be disadvantageous to the Fund. For
additional discussion of the tax treatment of "zero coupon" Treasury securities,
see "Distributions from the Fund" and "Tax Status."
 
  Stripped mortgage-related securities (hereinafter referred to as "Stripped
Mortgage Securities") are derivative multiclass mortgage securities. Stripped
Mortgage Securities are usually structured with two classes that receive
different proportions of the interest and principal distributions on a pool of
mortgage assets. Stripped Mortgage Securities may be issued by agencies or
instrumentalities of the U.S. Government, or by private originators of, or
investors in, mortgage loans, including savings and loan associations, mortgage
banks, commercial banks, investment banks and special purpose subsidiaries of
the foregoing. A common type of Stripped Mortgage Securities will have one class
receiving some of the interest and most of the principal from the mortgage
assets, while the other class will receive most of the interest and the
remainder of the principal. In the most extreme case, one class will receive all
of the interest (the interest-only or "IO" class), while the other class will
receive all of the principal (the principal-only or "PO" class). The yield to
maturity on an IO class is extremely sensitive to the rate of principal payments
(including prepayments) on the related underlying mortgage assets, and a rapid
rate of principal payments may have a material adverse effect on the securities'
yield to maturity. If the underlying mortgage assets experience greater than
anticipated prepayments of principal, the Fund may fail to fully recoup its
initial investment in these securities even if the security is rated AAA or Aaa.
Holders of PO securities are not entitled to any periodic payments of interest
prior to maturity. Accordingly, such securities usually trade at a deep discount
from their face or par value and are subject to greater fluctuations of market
value in response to changing interest rates than debt obligations of comparable
maturities which make current distributions of interest. Current federal tax law
requires that a holder (such as the Fund) of such securities accrue a portion of
the discount at which the security was purchased as income each year even though
the holder receives no interest payment in cash on the certificate during the
year. Such securities may involve greater risk than securities issued directly
by the U.S. Government, its agencies or instrumentalities.
 
  Although the market for government-issued IO and PO securities backed by
fixed-rate mortgages is increasingly liquid, certain of such securities may not
be readily marketable and will be considered illiquid for purposes of the Fund's
limitation on investments in illiquid securities. The Trustees of the Fund will
establish guidelines and standards for determining whether a particular
government-issued IO or PO backed by fixed-rate mortgages is liquid. Generally,
such a security may be deemed liquid if it can be disposed of promptly in the
ordinary course of business at a value reasonably close to that used in the
calculation of the net asset value per share. Stripped Mortgage Securities,
other than government-issued IO and PO securities backed by fixed-rate
mortgages, are presently considered by the staff of the SEC to be illiquid
securities and thus subject to the Fund's limitation on investment in illiquid
securities.
 
  OTHER SECURITIES. The Fund may invest in high quality debt obligations of
supranational lending entities organized or supported by several national
governments. Such supranational entities in which the Fund may invest include
the following: International Bank for Reconstruction and Development (World
Bank), established to promote reconstruction and economic development in its
member nations; European Coal and Steel Community, a partnership of certain
European countries created to establish a common market for coal and steel and
to further the economic development of its member countries; European Investment
Bank, established to finance investment projects that contribute to the balanced
development of the European Economic Community; European Bank for Reconstruction
& Development, whose objectives are to foster the transition toward open market
economies and to promote private and entrepreneurial initiative in countries of
central and eastern Europe; Inter-American Development Bank, established to
further the development of its Latin American member countries; African
Development Bank, established to contribute to the economic development
                                       12
<PAGE>   13
 
and social progress of its African member countries; Asian Development Bank,
established to promote economic growth and cooperation in Asia and the Far East.
 
  The Fund may also invest in U.S. dollar denominated debt issues of foreign
governments, their agencies and instrumentalities, and other foreign issuers.
 
  The Adviser believes that in many instances such foreign debt securities may
provide higher yields than securities of domestic issuers which have similar
maturities. Such securities may be subject to foreign government taxes which
would reduce the effective yield. Such securities may be less liquid than the
securities of U.S. corporations, and are certainly less liquid than securities
issued by the U.S. Government or its agencies.
 
  The above-described foreign investments involve certain risks, which should be
considered carefully by an investor in the Fund. These risks include political
or economic instability of the issuer or the country of issue, the difficulty of
predicting international trade patterns and the possibility of imposition of
exchange controls. Such securities may also be subject to greater fluctuations
in price than securities of U.S. corporations or of the U.S. Government. In
addition, there may be less publicly available information about a foreign
company than about a domestic company. Foreign companies generally are not
subject to uniform accounting, auditing and financial reporting standards
comparable to those applicable to domestic companies. There is generally less
government regulation of stock exchanges, brokers and listed companies abroad
than in the United States, and, with respect to certain foreign countries, there
is a possibility of expropriation or confiscatory taxation, or diplomatic
developments which could affect investment in those countries. Finally, in the
event of a default on any such foreign debt obligations, it may be more
difficult for the Fund to obtain or to enforce a judgment against the issuers of
such securities. Such investments will be made only when the Adviser believes
that higher yields justify the attendant risks.
- --------------------------------------------------------------------------------
INVESTMENT PRACTICES
- --------------------------------------------------------------------------------
 
  REPURCHASE AGREEMENTS. The Fund may enter into repurchase agreements with
banks or broker-dealers in order to earn a return on temporarily available cash.
A repurchase agreement is a short-term investment in which the purchaser (i.e.,
the Fund) acquires ownership of a debt security and the seller agrees to
repurchase the obligation at a future time and set price, thereby determining
the yield during the holding period. Repurchase agreements involve certain risks
in the event of a default by the other party. The Fund will not invest in
repurchase agreements maturing in more than seven days if any such investment,
together with any other illiquid securities held by the Fund, exceeds 15% of the
value of its net assets. In the event of the bankruptcy or other default of a
seller of a repurchase agreement, the Fund could experience delays in
liquidating the underlying securities, and the Fund could incur losses
including: (a) possible decline in the value of the underlying security during
the period while the Fund seeks to enforce its rights thereto; (b) possible lack
of access to income on the underlying security during this period; and (c)
expenses of enforcing its rights.
 
  For the purpose of investing in repurchase agreements, the Adviser may
aggregate the cash that certain funds advised or subadvised by the Adviser or
certain of its affiliates would otherwise invest separately into a joint
account. The cash in the joint account is then invested in repurchase agreements
and the funds that contributed to the joint account share pro rata in the net
revenue generated. The Adviser believes that the joint account produces
efficiencies and economies of scale that may contribute to reduced transaction
costs, higher returns, higher quality investments and greater diversity of
investments for the Fund than would be available to the Fund investing
separately. The manner in which the joint account is managed is subject to
conditions set forth in an SEC exemptive order authorizing this practice, which
conditions are designed to ensure the fair administration of the joint account
and to protect the amounts in that account.
 
  FORWARD COMMITMENTS. The Fund may purchase or sell debt securities on a
"when-issued" or "delayed delivery" basis ("Forward Commitments"). These
transactions occur when securities are purchased or sold by the Fund with
payment and delivery taking place in the future, frequently a month or more
after such transaction. The price is fixed on the date of the commitment, and
the seller continues to accrue interest on the securities covered by the Forward
Commitment until delivery and payment take place. At the time of settlement, the
market value of the securities may be more or less than the purchase or sale
price. The Fund may either settle a Forward Commitment by taking delivery of the
securities or may either resell or repurchase a Forward Commitment on or before
the settlement date in which event the Fund may reinvest the proceeds in another
Forward Commitment. When engaging in Forward Commitments, the Fund relies on the
other party to complete the transaction, should the other party fail to do so,
the Fund might lose a purchase or sale opportunity
 
                                       13
<PAGE>   14
 
that could be more advantageous than alternative opportunities at the time of
the failure. The Fund maintains a segregated account (which is marked to market
daily) of cash or liquid portfolio securities with the Fund's custodian in an
aggregate amount equal to the amount of its commitment as long as the obligation
to purchase or sell continues.
 
  LENDING OF SECURITIES. In order to generate additional income, the Fund may
lend its portfolio securities in an amount up to 33 1/3% of total assets to
broker-dealers, major banks or other recognized domestic institutional borrowers
of securities not affiliated with the Adviser. The borrower at all times during
the loan must maintain cash, cash equivalent or high-grade liquid debt
securities as collateral or provide to the Fund an irrevocable letter of credit
equal in value to at least 100% of the value of the securities loaned. During
the time portfolio securities are on loan, the Fund receives any dividends or
interest paid on such securities and may invest the collateral itself or receive
an agreed-upon amount of interest income from the borrower who has delivered the
collateral or a letter of credit. There are risks of delay in recovery and in
some cases even loss of rights in the collateral should the borrower of the
securities fail financially.
 
  INTEREST RATE TRANSACTIONS. The Fund may enter into interest rate swaps and
may purchase or sell interest rate caps, floors and collars. The Fund expects to
enter into these transactions primarily to preserve a return or spread on a
particular investment or portion of its portfolio. The Fund may also enter into
these transactions to protect against any increase in the price of securities
the Fund anticipates purchasing at a later date. The Fund does not intend to use
these transactions as speculative investments and will not enter into interest
rate swaps or sell interest rate caps or floors where it does not own or have
the right to acquire the underlying securities or other instruments providing
the income stream the Fund may be obligated to pay. Interest rate swaps involve
the exchange by the Fund with another party of their respective commitments to
pay or receive interest, e.g., an exchange of floating rate payments for
fixed-rate payments. The purchase of an interest rate cap entitles the
purchaser, to the extent that a specified index exceeds a predetermined interest
rate, to receive payments of interest on a contractually-based principal amount
from the party selling the interest rate cap. The purchase of an interest rate
floor entitles the purchaser, to the extent that a specified index falls below a
predetermined interest rate, to receive payments of interest on a
contractually-based principal amount from the party selling the interest rate
floor. An interest rate collar combines the elements of purchasing a cap and
selling a floor. The collar protects against an interest rate rise above the
maximum amount but foregoes the benefit of an interest rate decline below the
minimum amount. Interest rate swaps, caps, floors and collars will be treated as
illiquid securities and will, therefore, be subject to the Fund's investment
restriction limiting investment in illiquid securities. See the Statement of
Additional Information for further discussion on such interest rate
transactions.
 
  The net amount of the excess, if any, of the Fund's obligations over its
entitlements with respect to each interest rate swap will be accrued on a daily
basis and an amount of cash or liquid securities having an aggregate net asset
value at least equal to the accrued excess will be maintained in a segregated
account by the Fund's custodian. If the Fund enters into an interest rate swap
on other than a net basis, the Fund would maintain a segregated account in the
full amount accrued on a daily basis of the Fund's obligations with respect to
the swap.
 
  PORTFOLIO TURNOVER. The Fund may experience a high rate of portfolio turnover,
which may vary from year to year. The rate of portfolio turnover is not a
limiting factor when the Adviser deems it desirable to purchase or sell
securities or to engage in transactions in options, futures contracts and
related options. A 100% turnover rate would occur, for example, if all the
securities held by the Fund were replaced in a period of one year. Higher
portfolio turnover involves correspondingly greater brokerage commissions and
other transaction costs, which are borne directly by the Fund, and may result in
realization of short-term capital gains if securities are held for one year or
less which may be subject to applicable income taxes. See "Distributions from
the Fund." Although no assurance can be given with respect to future portfolio
turnover rates, it is anticipated that the Fund's rate of portfolio turnover
will not generally exceed 300%.
 
  USING OPTIONS, FUTURES CONTRACTS AND RELATED OPTIONS. The investment policies
of the Fund permit the Fund to engage in options, futures contracts and related
options.
 
  The Fund is authorized to purchase and sell over-the-counter options ("OTC
Options"). OTC Options are purchased from or sold to securities dealers,
financial institutions of other parties ("Counterparties") through direct
bilateral agreement with the Counterparty. The Fund will sell only OTC Options
(other than OTC currency options) that are subject to a buy-back provision
permitting the Fund to require to the Counterparty to sell the option back to
the Fund at a formula price within seven days. The staff of the SEC currently
takes the position that, in general, OTC Options on securities other than U.S.
Government securities purchased by the Fund, and portfolio securities covering
OTC Options sold by the Fund, are illiquid securities subject to the Fund's
limitation on illiquid securities.
 
                                       14
<PAGE>   15
 
  The Fund presently expects to utilize options, futures contracts and options
thereon in several different ways, depending upon the status of a Fund's
portfolio and the Adviser's expectations concerning the securities markets. See
the Statement of Additional Information for discussion of options, futures
contracts and related options.
 
  Potential Risks of Options, Futures Contracts and Related Options. In certain
cases, the options and futures markets provide investment or risk management
opportunities that are not available from direct investments in securities. In
addition, some strategies can be performed with greater ease and at lower cost
by utilizing the options and futures markets rather than purchasing or selling
portfolio securities. However, the purchase and sale of options, futures
contracts and related options involve risks different from those involved with
direct investments in underlying securities. While utilization of options,
futures contracts and related options may be advantageous to the Fund, if the
Adviser is not successful in employing such instruments in managing the Fund's
investments, the Fund's performance will be worse than if the Fund did not make
such investments. In addition, the Fund would pay commissions and other costs in
connection with such investments, which may increase the Fund's expenses and
reduce its return.
 
  In order to prevent leverage in connection with the purchase of futures
contracts or call options thereon by the Fund, an amount of cash or liquid
securities equal to the market value of the obligation under the futures
contracts or options (less any related margin deposits) will be maintained in a
segregated account with the Custodian. The Fund may not invest more than 15% of
its net assets in illiquid securities, including certain OTC Options deemed
illiquid and repurchase agreements which have a maturity of longer than seven
days. A more complete discussion of the potential risks involved in transactions
in options, futures contracts and related options, is contained in the Statement
of Additional Information.
 
  EURODOLLAR INSTRUMENTS. The Fund may invest in Eurodollar instruments for
hedging purposes. Eurodollar instruments are essentially U.S. dollar-denominated
futures contracts or options thereon that are linked to the London Interbank
Offered Rate ("LIBOR"). Eurodollar futures contracts enable purchasers to obtain
a fixed-rate for the lending of funds and sellers to obtain a fixed-rate for
borrowings. The Fund intends to use Eurodollar futures contracts and options
thereon to hedge against changes in LIBOR to which many short-term borrowings
and floating rate securities are linked. Eurodollar instruments are subject to
the same limitations and risks as other futures contracts and options thereon as
described above and in the Statement of Additional Information.
 
  PORTFOLIO TRANSACTIONS AND BROKERAGE PRACTICES. The Adviser is responsible for
the placement of orders for the purchase and sale of portfolio securities for
the Fund. The debt securities in which the Fund invests are generally traded in
the over-the-counter market. Such securities are generally traded on a net basis
with dealers acting as principal for their own accounts without a stated
commission, although the prices of the securities usually include a profit to
the dealers. It is the policy of the Fund to seek to obtain the best net results
taking into account such factors as price (including the applicable dealer
spread), the size, type and difficulty of the transaction involved, the firm's
general execution and operational facilities, the firm's risk in positioning the
securities involved, and the provision of supplemental investment research by
the firm. While the Fund seeks reasonably competitive dealer spreads, the Fund
will not necessarily be paying the lowest spread available. Brokerage
commissions are paid on transactions in listed options, futures contracts and
options thereon. The Adviser is authorized to place portfolio transactions with
broker-dealers participating in the distribution of shares of the Fund and other
funds distributed by the Distributor if it reasonably believes that the quality
of the execution and any commissions are comparable to that available from other
qualified firms. The Adviser is authorized to pay higher commissions to
brokerage firms that provide it with investment and research information than to
firms which do not provide such service if the Adviser determines that such
commissions are reasonable in relation to the overall services provided. The
information received may be used by the Adviser in managing the assets of other
advisory accounts as well as in the management of the assets of the Fund.
 
  INVESTMENT RESTRICTIONS. The Fund has adopted certain fundamental investment
restrictions which, like the investment objective, may not be changed without
approval by a vote of a majority of the outstanding voting shares of the Fund
(as defined in the Investment Company Act of 1940, as amended (the "1940 Act")).
These restrictions provide, among other things, that the Fund may not:
 
  1. Invest more than 5% of its assets in the securities of any one issuer
     (except the U.S. Government, its agencies and instrumentalities) or
     purchase more than 10% of the outstanding voting securities of any one
     issuer, except that the Fund may purchase securities of other investment
     companies to the extent permitted by (i) the 1940 Act, as amended from time
     to time, (ii) the rules and regulations promulgated by the SEC under the
     1940 Act, as amended from time to time, or (iii) an exemption or other
     relief from the provisions of the 1940 Act.
 
                                       15
<PAGE>   16
 
  2. Purchase or sell commodities or commodity contracts except that the Fund
     may enter into transactions in options, futures contracts or related
     options including forward commitments.
 
  3. Issue senior securities, as defined in the 1940 Act, except that this
     restriction shall not be deemed to prohibit the Fund from (i) making and
     collateralizing any permitted borrowings, (ii) making any permitted loans
     of its portfolio securities, or (iii) entering into repurchase agreements,
     utilizing options, futures contracts, options on futures contracts, forward
     commitments and other investment strategies and instruments that would be
     considered "senior securities" but for the maintenance by the Fund of a
     segregated account with its custodian or some other form of "cover."
 
  4. Borrow in excess of 5% of the market or other fair value of its total
     assets; or pledge its assets to an extent greater than 5% of the market or
     other fair value of its total assets. Any such borrowings shall be from
     banks and shall be undertaken only as a temporary measure for extraordinary
     or emergency purposes. Margin deposits or payments in connection with the
     writing of options, or in connection with the purchase or sale of futures
     contracts and related options, are not deemed to be a pledge or other
     encumbrance.
 
  5. Make any investment which would cause more than 25% of the market or other
     fair value of its total assets to be invested in the securities of issuers,
     all of which conduct their principal business activities in the same
     industry. This restriction does not apply to obligations issued or
     guaranteed by the U.S. Government, its agencies or instrumentalities.
 
  6. Write, purchase or sell puts, calls or combinations thereof, except that
     the Fund may (i) write covered or fully collateralized call options, write
     secured put options, and enter into closing or offsetting purchase
     transactions with respect to such options, (ii) purchase and sell options
     to the extent that the premiums paid for all such options owned at any time
     do not exceed 10% of its total assets and (iii) engage in transactions in
     interest rate futures contracts and related options provided that such
     transactions are entered into for bona fide hedging purposes (or that the
     underlying commodity value of the Fund's long positions do not exceed the
     sum of certain identified liquid investments as specified in Commodity
     Futures Trading Commission ("CFTC") regulations), provided further that the
     aggregate initial margin and premiums do not exceed 5% of the fair market
     value of the Fund's total assets, and provided further that the Fund may
     not purchase futures contracts or related options if more than 30% of the
     Fund's total assets would be so invested.
 
  Additional investment restrictions are set forth in the Statement of
Additional Information.
- --------------------------------------------------------------------------------
INVESTMENT ADVISORY SERVICES
- --------------------------------------------------------------------------------
 
  THE ADVISER. The Adviser is a wholly-owned subsidiary of Van Kampen
Investments Inc. ("Van Kampen"). Van Kampen is a diversified asset management
company with more than two million retail investor accounts, extensive
capabilities for managing institutional portfolios, and more than $65 billion
under management or supervision. Van Kampen's more than 50 open-end and 39
closed-end funds and more than 2,500 unit investment trusts are professionally
distributed by leading financial advisers nationwide. Van Kampen Funds Inc., the
Distributor of the Fund and the sponsor of the funds mentioned above, is also a
wholly-owned subsidiary of Van Kampen. Van Kampen is an indirect wholly-owned
subsidiary of Morgan Stanley Dean Witter & Co. The Adviser's principal office is
located at One Parkview Plaza, Oakbrook Terrace, Illinois 60181.
 
  Morgan Stanley Dean Witter & Co. and various of its directly or indirectly
owned subsidiaries, including Morgan Stanley Asset Management, Inc., an
investment adviser, Morgan Stanley & Co. Incorporated, a registered
broker-dealer and investment adviser, and Morgan Stanley International, are
engaged in a wide range of financial services. Their principal businesses
include securities underwriting, distribution and trading; merger, acquisition,
restructuring and other corporate finance advisory activities; merchant banking;
stock brokerage and research services; credit services; asset management;
trading of futures, options, foreign exchange, commodities and swaps (involving
foreign exchange, commodities, indices and interest rates); real estate advice,
financing and investing; and securities lending.
 
                                       16
<PAGE>   17
 
  ADVISORY AGREEMENTS. The Fund retains the Adviser to manage the investment of
its assets and to place orders for the purchase and sale of its portfolio
securities. Under an investment advisory agreement between the Adviser and the
Fund (the "Advisory Agreement"), the Fund pays the Adviser a monthly fee
computed on average daily net assets of the Fund at the annual rate of 0.60% of
the Fund's average daily net assets.
 
  Under the Advisory Agreement, the Fund also reimburses the Adviser for the
costs of the Fund's accounting services, which include maintaining its financial
books and records and calculating its daily net asset value. Operating expenses
paid by the Fund include service fees, distribution fees, custodian fees, legal
and accounting fees, the costs of reports and proxies to shareholders, trustees'
fees (other than those who are affiliated persons as defined in the 1940 Act of
the Adviser, Distributor or Van Kampen), and all other business expenses not
specifically assumed by the Adviser. Advisory (management) fee and total
operating expense ratios are shown under the caption "Annual Fund Operating
Expenses and Example" herein.
 
  From time to time the Adviser or the Distributor may voluntarily undertake to
reduce the Fund's expenses by reducing the fees payable to them to the extent
of, or bearing expenses in excess of, such limitations as they may establish.
 
  The Adviser may utilize, at its own expense, credit analysis, research and
trading support services provided by its affiliate, Van Kampen Investment
Advisory Corp. ("Advisory Corp.").
 
  PERSONAL INVESTMENT POLICIES. The Fund and the Adviser have adopted Codes of
Ethics designed to recognize the fiduciary relationship between the Fund and the
Adviser and its employees. The Codes permit directors, trustees, officers and
employees to buy and sell securities for their personal accounts subject to
certain restrictions. Persons with access to certain sensitive information are
subject to pre-clearance and other procedures designed to prevent conflicts of
interest.
 
  PORTFOLIO MANAGEMENT. Ted Mundy has been primarily responsible for the
day-to-day management of the Fund's investment portfolio since June 30, 1994.
Mr. Mundy is Vice President of the Adviser. Since June 1995, Mr. Mundy has been
a Vice President of Advisory Corp. From September 1990 to June 1994, Mr. Mundy
was a portfolio manager with AMR Investment Services, Inc.
 
- --------------------------------------------------------------------------------
ALTERNATIVE SALES ARRANGEMENTS
- --------------------------------------------------------------------------------
 
  The Alternative Sales Arrangements permits an investor to choose the method of
purchasing shares of the Fund that is most beneficial given the amount of the
purchase and the length of time the investor expects to hold the shares.
 
  CLASS A SHARES. Class A shares are sold at net asset value plus an initial
maximum sales charge of up to 4.75% at the time of purchase (4.99% of the net
amount invested), reduced on investments of $100,000 or more. Investments of $1
million or more are not subject to any sales charge at the time of purchase, but
a CDSC of 1.00% may be imposed on certain redemptions made within one year of
the purchase. Class A shares are subject to an ongoing service fee at an annual
rate of up to 0.25% of the Fund's aggregate average daily net assets
attributable to the Class A shares. Certain purchases of Class A shares qualify
for reduced initial sales charges. See "Purchase of Shares -- Class A Shares."
 
  CLASS B SHARES. Class B shares are sold at net asset value and are subject to
a deferred sales charge if redeemed within five years of purchase. Class B
shares are subject to an ongoing service fee at an annual rate of up to 0.25% of
the Fund's aggregate average daily net assets attributable to the Class B shares
and an ongoing distribution fee at an annual rate of up to 0.75% of the Fund's
aggregate average daily net assets attributable to the Class B shares. Class B
shares enjoy the benefit of permitting all of the investor's dollars to work
from the time the investment is made. The ongoing distribution fee paid by Class
B shares will cause such shares to have a higher expense ratio and to pay lower
dividends than those related to Class A shares. Class B shares convert
automatically to Class A shares eight years after the end of the calendar month
in which the shareholder's order to purchase was accepted. See "Purchase of
Shares -- Class B Shares."
 
  CLASS C SHARES. Class C shares are sold at net asset value and are subject to
a deferred sales charge if redeemed within one year of purchase. Class C shares
are subject to an ongoing service fee at an annual rate of up to 0.25% of the
Fund's aggregate average daily net assets attributable to the Class C shares and
an ongoing distribution fee at an annual rate of up to 0.75% of the Fund's
aggregate average daily net assets attributable to the Class C shares. Class C
shares enjoy the benefit of permitting all of the investor's dollars to work
from the time the investment is made. The ongoing distribution
 
                                       17
<PAGE>   18
 
fee paid by Class C shares will cause such shares to have a higher expense ratio
and to pay lower dividends than those related to Class A shares. See "Purchase
of Shares -- Class C Shares."
 
  CONVERSION FEATURE. Class B shares purchased on or after June 1, 1996 and any
dividend reinvestment plan shares received thereon, automatically convert to
Class A shares eight years after the end of the calendar month in which the
shares were purchased. Class B shares purchased before June 1, 1996, and any
dividend reinvestment plan shares received thereon, automatically convert to
Class A shares six years after the end of the calendar month in which the shares
were purchased. Class C shares purchased before January 1, 1997, and any
dividend reinvestment plan shares received thereon, automatically convert to
Class A shares ten years after the end of the calendar month in which such
shares were purchased. Such conversion will be on the basis of the relative net
asset values per share, without the imposition of any sales load, fee or other
charge. The conversion schedule applicable to a share acquired through the
exchange privilege is determined by reference to the Participating Fund from
which such share was originally purchased.
 
  The conversion of such shares to Class A shares is subject to the continuing
availability of an opinion of counsel to the effect that (i) the assessment of
the higher distribution fee and transfer agency costs with respect to such
shares does not result in the Fund's dividends or distributions constituting
"preferential dividends" under the Internal Revenue Code of 1986, as amended
(the "Code"), and (ii) the conversion of shares does not constitute a taxable
event under federal income tax law. The conversion may be suspended if such an
opinion is no longer available and such shares might continue to be subject to
the higher aggregate fees applicable to such shares for an indefinite period.
 
  FACTORS FOR CONSIDERATION. In deciding which class of shares to purchase,
investors should take into consideration their investment goals, present and
anticipated purchase amounts, time horizons and temperaments. Investors should
consider whether, during the anticipated life of their investment in the Fund,
the higher aggregate fees and CDSC on Class B shares and Class C shares would be
less than the initial sales charge on Class A shares purchased at the same time,
and to what extent such differential would be offset by the higher dividends per
share on Class A shares. To assist investors in making this determination, the
table under the caption "Annual Fund Operating Expenses and Example" sets forth
examples of the charges applicable to each class of shares. In this regard,
Class A shares may be more beneficial to the investor who qualifies for reduced
initial sales charges or purchases at net asset value. It is presently the
policy of the Distributor not to accept any order of $500,000 or more for Class
B shares or any order of $1 million or more for Class C shares as it ordinarily
would be more beneficial for such investor to purchase Class A shares.
 
  Class A shares are not subject to an ongoing distribution fee and,
accordingly, receive correspondingly higher dividends per share. However,
because initial sales charges are deducted at the time of purchase for accounts
under $1 million, investors in Class A shares do not have all their funds
invested initially and, therefore, initially own fewer shares. Other investors
might determine that it is more advantageous to purchase either Class B shares
or Class C shares and have all their funds invested initially, although
remaining subject to a CDSC. Ongoing distribution fees on Class B shares and
Class C shares may be offset to the extent of the additional funds originally
invested and any return realized on those funds. However, there can be no
assurance as to the return, if any, which will be realized on such additional
funds. For investments held for ten years or more, the relative value upon
liquidation of the three classes tends to favor Class A shares or Class B
shares, rather than Class C shares.
 
  Class A shares may be appropriate for investors who prefer to pay the sales
charge up front, want to take advantage of the reduced sales charges available
on larger investments, wish to maximize their current income from the start,
prefer not to pay redemption charges or have a longer-term investment horizon.
In addition, the check writing privilege is only available for Class A shares
(see "Shareholder Services -- Check Writing Privilege"). Class B shares may be
appropriate for investors who wish to avoid a front-end sales charge, put 100%
of their investment dollars to work immediately or have a longer-term investment
horizon. Class C shares may be appropriate for investors who wish to avoid a
front-end sales charge, put 100% of their investment dollars to work
immediately, have a shorter-term investment horizon or desire a short CDSC
schedule.
 
  The distribution expenses incurred by the Distributor in connection with the
sale of the shares will be reimbursed, in the case of Class A shares, from the
proceeds of the initial sales charge and, in the case of Class B shares and
Class C shares, from the proceeds of the ongoing distribution fee and any CDSC
incurred upon redemption within five years or one year, respectively, of
purchase. Sales personnel of broker-dealers distributing the Fund's shares and
other persons entitled to receive compensation for selling such shares may
receive differing compensation for selling such shares. INVESTORS SHOULD
UNDERSTAND THAT THE PURPOSE AND FUNCTION OF THE CDSC AND ONGOING DISTRIBUTION
FEE WITH RESPECT TO THE CLASS B SHARES
                                       18
<PAGE>   19
 
AND CLASS C SHARES ARE THE SAME AS THOSE OF THE INITIAL SALES CHARGE WITH
RESPECT TO CLASS A SHARES. See "Distribution and Service Plans."
 
  GENERAL. Dividends paid by the Fund with respect to Class A shares, Class B
shares and Class C shares will be calculated in the same manner at the same time
on the same day except that the higher distribution fees and transfer agency
costs relating to Class B shares or Class C shares will be borne by the
respective class. See "Distributions from the Fund." Shares of the Fund may be
exchanged, subject to certain limitations, for shares of the same class of
certain other mutual funds advised by the Adviser and its affiliates and
distributed by the Distributor. See "Shareholders Services -- Exchange
Privilege."
 
- --------------------------------------------------------------------------------
PURCHASE OF SHARES
- --------------------------------------------------------------------------------
 
  The Fund offers three classes of shares to the public on a continuous basis
through the Distributor as principal underwriter, which is located at One
Parkview Plaza, Oakbrook Terrace, Illinois 60181. Shares also are offered
through members of the National Association of Securities Dealers, Inc. ("NASD")
who are acting as securities dealers ("dealers") and NASD members or eligible
non-NASD members who are acting as brokers or agents for investors ("brokers").
The term "dealers" and "brokers" are sometimes referred to herein as "authorized
dealers."
 
  Initial investments must be at least $500 for each class of shares, and
subsequent investments must be at least $25 for each class of shares. Both
minimums may be waived by the Distributor for plans involving periodic
investments. Shares of the Fund may be sold in foreign countries where
permissible. The Fund and the Distributor reserve the right to refuse any order
for the purchase of shares. The Fund also reserves the right to suspend the sale
of the Fund's shares in response to conditions in the securities markets or for
other reasons.
 
  Shares of the Fund may be purchased on any business day through authorized
dealers. Shares also may be purchased by completing the application accompanying
this Prospectus and forwarding the application, through the authorized dealer,
to the shareholder service agent, Van Kampen Investor Services Inc. ("Investor
Services"), a wholly-owned subsidiary of Van Kampen. When purchasing shares of
the Fund, investors must specify whether the purchase is for Class A shares,
Class B shares or Class C shares.
 
  Shares are offered at the next determined net asset value per share, plus a
front-end or deferred sales charge depending on the class of shares chosen by
the investor, as shown in the tables herein. Net asset value per share for each
class is determined once daily as of the close of trading on the New York Stock
Exchange (the "Exchange") (currently 4:00 p.m., New York time) each day the
Exchange is open. Net asset value per share for each class is determined by
dividing the value of the Fund's securities, cash and other assets (including
accrued interest) attributable to such class less all liabilities (including
accrued expenses) attributable to such class, by the total number of shares of
the class outstanding.
 
  U.S. Government securities and agency obligations are valued at the last
reported bid price. Listed options are valued at the last reported sale price on
the exchange on which such option is traded, or, if no sales are reported, at
the mean between the last reported bid and asked prices. Options for which
market quotations are not readily available are valued at a fair value under a
method approved by the Trustees.
 
  Short-term investments with a maturity of 60 days or less when purchased are
valued at cost plus interest earned (amortized cost), which approximates market
value. Short-term investments with a maturity of more than 60 days when
purchased are valued based on market quotations until the remaining days to
maturity becomes less than 61 days. From such time, until maturity, the
investments are valued at amortized cost using the value of the investment on
the 61st day. See the notes to financial statements in the Statement of
Additional Information.
 
  Generally, the net asset values per share of the Class A shares, Class B
shares, and Class C shares are expected to be substantially the same. Under
certain circumstances, however, the per share net asset values of the Class A
shares, Class B shares and Class C shares may differ from one another,
reflecting the daily expense accruals of the higher distribution fee and
transfer agency costs applicable with respect to the Class B shares and Class C
shares and the differential in the dividends paid on the classes of shares. The
price paid for shares purchased is based on the next calculation of net asset
value (plus sales charges, where applicable) after an order is received by an
authorized dealer provided such order is transmitted to the Distributor prior to
the Distributor's close of business on such day. Orders received by authorized
 
                                       19
<PAGE>   20
 
dealers after the close of the Exchange are priced based on the next close
provided they are received by the Distributor prior to the Distributor's close
of business on such day. It is the responsibility of authorized dealers to
transmit orders received by them to the Distributor so they will be received
prior to such time. Orders of less than $500 are mailed by the authorized dealer
and processed at the offering price next calculated after acceptance by Investor
Services.
 
  Each class of shares represents an interest in the same portfolio of
investments of the Fund and has the same rights except that (i) Class B shares
and Class C shares bear the expenses of the deferred sales arrangement and any
expenses (including the higher distribution fee and transfer agency costs)
resulting from such sales arrangement, (ii) generally, each class has exclusive
voting rights with respect to approvals of the Rule 12b-1 distribution plan
pursuant to which its distribution fee or service fee is paid, (iii) each class
of shares has different exchange privileges, (iv) certain classes of shares are
subject to a conversion feature and (v) certain classes of shares have different
shareholder service options available. The net income attributable to Class B
shares and Class C shares and the dividends payable on Class B shares and Class
C shares will be reduced by the amount of the distribution fee and other
expenses associated with such shares. Sales personnel of authorized dealers
distributing the Fund's shares and other persons entitled to receive
compensation for selling such shares may receive differing compensation for
selling Class A shares, Class B shares or Class C shares.
 
  The Distributor may from time to time implement programs under which an
authorized dealer's sales force may be eligible to win nominal awards for
certain sales efforts or under which the Distributor will reallow to any
authorized dealer that sponsors sales contests or recognition programs
conforming to criteria established by the Distributor, or participates in sales
programs sponsored by the Distributor, an amount not exceeding the total
applicable sales charges on the sales generated by the authorized dealer at the
public offering price during such programs. Other programs provide, among other
things and subject to certain conditions, for certain favorable distribution
arrangements for shares of the Fund. Also, the Distributor in its discretion may
from time to time, pursuant to objective criteria established by the
Distributor, pay fees to, and sponsor business seminars for, qualifying
authorized dealers for certain services or activities which are primarily
intended to result in sales of shares of the Fund. Fees may include payment for
travel expenses, including lodging, incurred in connection with trips taken by
invited registered representatives and members of their families to locations
within or outside of the United States for meetings or seminars of a business
nature. In some instances, additional compensation or promotional incentives may
be offered to brokers, dealers or financial intermediaries that have sold or may
sell significant amounts of shares during specified periods of time. The
Distributor may provide additional compensation to Edward D. Jones & Co. or an
affiliate thereof based on a combination of its sales of shares and increases in
assets under management. All of the foregoing payments are made by the
Distributor out of its own assets. Such fees paid for such services and
activities with respect to the Fund will not exceed in the aggregate 1.25% of
the average total daily net assets of the Fund on an annual basis. These
programs will not change the price an investor will pay for shares or the amount
that a Fund will receive from such sale.
 
CLASS A SHARES
 
  The public offering price of Class A shares is the net asset value plus a
sales charge, as set forth below.
 
SALES CHARGE TABLE
 
<TABLE>
<CAPTION>
                                                                                               REALLOWED
                                                                                AS % OF       TO DEALERS
                                                                 AS % OF       NET AMOUNT     (AS A % OF
                     SIZE OF INVESTMENT                       OFFERING PRICE    INVESTED    OFFERING PRICE)
<S>                                                           <C>              <C>          <C>
- -----------------------------------------------------------------------------------------------------------
Less than $100,000..........................................      4.75%          4.99%           4.25%
$100,000 but less than $250,000.............................      3.75%          3.90%           3.25%
$250,000 but less than $500,000.............................      2.75%          2.83%           2.25%
$500,000 but less than $1,000,000...........................      2.00%          2.04%           1.75%
$1,000,000 or more*.........................................      *               *             *
- -----------------------------------------------------------------------------------------------------------
</TABLE>
 
* No sales charge is payable at the time of purchase on investments of $1
  million or more, although for such investments the Fund imposes a CDSC of
  1.00% on redemptions made within one year of the purchase. A commission will
  be paid to authorized dealers who initiate and are responsible for purchases
  of $1 million or more as follows: 1.00% on sales to $2 million, plus 0.80% on
  the next $1 million, and 0.50% on the excess over $3 million.
 
                                       20
<PAGE>   21
 
  In addition to the reallowances from the applicable public offering price
described above, the Distributor may, from time to time, pay or allow additional
reallowances or promotional incentives, in the form of cash or other
compensation, to authorized dealers that sell shares of the Fund. Authorized
dealers which are reallowed all or substantially all of the sales commissions
may be deemed to be underwriters for purposes of the Securities Act of 1933, as
amended.
 
  The Distributor may also pay financial institutions (which may include banks)
and other industry professionals that provide services to facilitate
transactions in shares of the Fund for their clients a transaction fee up to the
level of the reallowance allowable to authorized dealers described herein. Such
financial institutions, other industry professionals and authorized dealers are
hereinafter referred to as "Service Organizations." Banks are currently
prohibited under the Glass-Steagall Act from providing certain underwriting or
distribution services. If banking firms were prohibited from acting in any
capacity or providing any of the described services, the Distributor would
consider what action, if any, would be appropriate. The Distributor does not
believe that termination of a relationship with a bank would result in any
material adverse consequences to the Fund. State securities laws regarding
registration of banks and other financial institutions may differ from the
interpretations of federal law expressed herein, and banks and other financial
institutions may be required to register as dealers pursuant to certain state
laws.
 
QUANTITY DISCOUNTS
 
  Investors purchasing Class A shares may, under certain circumstances, be
entitled to pay reduced sales charges. The circumstances under which such
investors may pay reduced sales charges are described below.
 
  Investors, or their authorized dealers, must notify the Fund at the time of
the purchase order whenever a quantity discount is applicable to purchases. Upon
such notification, an investor will receive the lowest applicable sales charge.
Quantity discounts may be modified or terminated at any time. For more
information about quantity discounts, investors should contact their authorized
dealer or the Distributor.
 
  A person eligible for a reduced sales charge includes an individual, his or
her spouse and children under 21 years of age and any corporation, partnership
or sole proprietorship which is 100% owned, either alone or in combination, by
any of the foregoing; a trustee or other fiduciary purchasing for a single trust
or for a single fiduciary account, or a "company" as defined in Section 2(a)(8)
of the 1940 Act.
 
  As used herein, "Participating Funds" refers to certain open-end investment
companies advised by the Adviser or Advisory Corp. and distributed by the
Distributor as determined from time to time by the Fund's Board of Trustees.
 
  Volume Discounts. The size of investment shown in the preceding sales charge
table applies to the total dollar amount being invested by any person in shares
of the Fund, or in any combination of shares of the Fund and shares of other
Participating Funds, although other Participating Funds may have different sales
charges.
 
  Cumulative Purchase Discount. The size of investment shown in the preceding
sales charge table may also be determined by combining the amount being invested
in shares of the Participating Funds plus the current offering price of all
shares of the Participating Funds which have been previously purchased and are
still owned.
 
  Letter of Intent. A Letter of Intent provides an opportunity for an investor
to obtain a reduced sales charge by aggregating the investments over a 13-month
period to determine the sales charge as outlined in the preceding sales charge
table. The size of investment shown in the preceding sales charge table also
includes purchases of shares of the Participating Funds over a 13-month period
based on the total amount of intended purchases plus the value of all shares of
the Participating Funds previously purchased and still owned. An investor may
elect to compute the 13-month period starting up to 90 days before the date of
execution of a Letter of Intent. Each investment made during the period receives
the reduced sales charge applicable to the total amount of the investment goal.
If the goal is not achieved within the period, the investor must pay the
difference between the sales charge applicable to the purchases made and the
sales charges previously paid. The initial purchase must be for an amount equal
to at least 5% of the minimum total purchased amount of the level selected. If
trades not initially made under a Letter of Intent subsequently qualify for a
lower sales charge through the 90-day back-dating provisions, an adjustment will
be made at the expiration of the Letter of Intent to give effect to the lower
charge. Such adjustments in sales charge will be used to purchase additional
shares for the shareholder at the applicable discount category. Additional
information is contained in the application accompanying this Prospectus.
 
                                       21
<PAGE>   22
 
OTHER PURCHASE PROGRAMS
 
  Purchasers of Class A shares may be entitled to reduced initial sales charges
in connection with unit investment trust reinvestment programs and purchases by
registered representatives of selling firms or purchases by persons affiliated
with the Fund or the Distributor. The Fund reserves the right to modify or
terminate these arrangements at any time.
 
  Unit Investment Trust Reinvestment Programs.  The Fund permits unitholders of
unit investment trusts to reinvest distributions from such trusts in Class A
shares of the Fund at net asset value with no minimum initial or subsequent
investment requirement, if the administrator of an investor's unit investment
trust program meets certain uniform criteria relating to cost savings by the
Fund and the Distributor. The total sales charge for all other investments made
from unit trust distributions will be 1.00% of the offering price (1.01% of net
asset value). Of this amount, the Distributor will pay to the authorized dealer,
if any, through which such participation in the qualifying program was initiated
0.50% of the offering price as a dealer concession or agency commission. Persons
desiring more information with respect to this program, including the applicable
terms and conditions thereof, should contact their authorized dealer or the
Distributor.
 
  The administrator of such a unit investment trust must have an agreement with
the Distributor pursuant to which the administrator will (1) submit a single
bulk order and make payment with a single remittance for all investments in the
Fund during each distribution period by all investors who choose to invest in
the Fund through the program and (2) provide Investor Services with appropriate
backup data for each participating investor in a computerized format fully
compatible with Investor Services' processing system.
 
  As further requirements for obtaining these special benefits, the Fund also
requires that all dividends and other distributions by the Fund be reinvested in
additional shares without any systematic withdrawal program. There will be no
minimum for reinvestments from unit investment trusts. The Fund will send
account activity statements to such participants on a monthly basis only, even
if their investments are made more frequently. The Fund reserves the right to
modify or terminate this program at any time.
 
  NAV Purchase Options. Class A shares of the Fund may be purchased at net asset
value, upon written assurance that the purchase is made for investment purposes
and that the shares will not be resold except through redemption by the Fund,
by:
 
  (1) Current or retired trustees or directors of funds advised by the Adviser
      or Advisory Corp. and such persons' families and their beneficial
      accounts.
 
  (2) Current or retired directors, officers and employees of Morgan Stanley
      Group Inc. and any of its subsidiaries, employees of an investment
      subadviser to any fund described in (1) above or an affiliate of such
      subadviser, and such persons' families and their beneficial accounts.
 
  (3) Directors, officers, employees and registered representatives of financial
      institutions that have a selling group agreement with the Distributor and
      their spouses and children under 21 years of age when purchasing for any
      accounts they beneficially own, or, in the case of any such financial
      institution, when purchasing for retirement plans for such institution's
      employees; provided that such purchases are otherwise permitted by such
      institutions.
 
  (4) Registered investment advisers who charge a fee for their services, trust
      companies and bank trust departments investing on their own behalf or on
      behalf of their clients. The Distributor may pay Participating Dealers
      through which purchases are made an amount up to 0.50% of the amount
      invested, over a 12-month period.
 
  (5) Trustees and other fiduciaries purchasing shares for retirement plans
      which invest in multiple fund families through broker-dealer retirement
      plan alliance programs that have entered into agreements with the
      Distributor and which are subject to certain minimum size and operational
      requirements. Trustees and other fiduciaries should refer to the Statement
      of Additional Information for further detail with respect to such alliance
      programs.
 
  (6) Beneficial owners of shares of Participating Funds held by a retirement
      plan or held in a tax-advantaged retirement account who purchase shares of
      the Fund with proceeds from distributions from such a plan or retirement
      account other than distributions taken to correct an excess contribution.
 
  (7) Accounts as to which a bank or broker-dealer charges an account management
      fee ("wrap accounts"), provided the bank or broker-dealer has a separate
      agreement with the Distributor.
 
                                       22
<PAGE>   23
 
  (8) Trusts created under pension, profit sharing or other employee benefit
      plans qualified under Section 401(a) of the Code, or custodial accounts
      held by a bank created pursuant to Section 403(b) of the Code and
      sponsored by non-profit organizations defined under Section 501(c)(3) of
      the Code and assets held by an employer or trustee in connection with an
      eligible deferred compensation plan under Section 457 of the Code. Such
      plans will qualify for purchases at net asset value provided, for plans
      initially establishing accounts with the Distributor in the Participating
      Funds after February 1, 1997, that (1) the initial amount invested in the
      Participating Funds is at least $500,000 or (2) such shares are purchased
      by an employer sponsored plan with more than 100 eligible employees. Such
      plans that have been established with a Participating Fund or have
      received proposals from the Distributor prior to February 1, 1997 based on
      net asset value purchase privileges previously in effect will be qualified
      to purchase shares of the Participating Funds at net asset value for
      accounts established on or before May 1, 1997. Section 403(b) and similar
      accounts for which Van Kampen Trust Company serves as custodian will not
      be eligible for net asset value purchases based on the aggregate
      investment made by the plan or the number of eligible employees, except
      under certain uniform criteria established by the Distributor from time to
      time. Prior to February 1, 1997, a commission will be paid to authorized
      dealers who initiate and are responsible for such purchases within a
      rolling twelve-month period as follows: 1.00% on sales to $5 million, plus
      0.50% on the next $5 million, plus 0.25% on the excess over $10 million.
      For purchases on February 1, 1997 and thereafter, a commission will be
      paid as follows: 1.00% on sales to $2 million, plus 0.80% on the next $1
      million, plus 0.50% on the next $47 million, plus 0.25% on the excess over
      $50 million.
 
  (9) Individuals who are members of a "qualified group". For this purpose, a
      qualified group is one which (i) has been in existence for more than six
      months, (ii) has a purpose other than to acquire shares of the Fund or
      similar investments, (iii) has given and continues to give its endorsement
      or authorization, on behalf of the group, for purchase of shares of the
      Fund and Participating Funds, (iv) has a membership that the authorized
      dealer can certify as to the group's members and (v) satisfies other
      uniform criteria established by the Distributor for the purpose of
      realizing economies of scale in distributing such shares. A qualified
      group does not include one whose sole organizational nexus, for example,
      is that its participants are credit card holders of the same institution,
      policy holders of an insurance company, customers of a bank or
      broker-dealer, clients of an investment adviser or other similar groups.
      Shares purchased in each group's participants account in connection with
      this privilege will be subject to a CDSC of 1.00% in the event of
      redemption within one year of purchase, and a commission will be paid to
      authorized dealers who initiate and are responsible for such sales to each
      individual as follows: 1.00% on sales to $2 million, plus 0.80% on the
      next $1 million and 0.50% on the excess over $3 million.
 
The term "families" includes a person's spouse, children under 21 years of age
and grandchildren, parents, and a person's spouse's parents.
 
  Purchase orders made pursuant to clause (4) may be placed either through
authorized dealers as described above or directly with Investor Services by the
investment adviser, trust company or bank trust department, provided that
Investor Services receives federal funds for the purchase by the close of
business on the next business day following acceptance of the order. An
authorized dealer may charge a transaction fee for placing an order to purchase
shares pursuant to this provision or for placing a redemption order with respect
to such shares. Authorized dealers will be paid a service fee as described
herein under "Distribution and Service Plans" on purchases made as described in
(3) through (9) above. The Fund may terminate, or amend the terms of, offering
shares of the Fund at net asset value to such groups at any time.
 
CLASS B SHARES
 
  Class B shares are offered at net asset value. Class B shares which are
redeemed within five years of purchase are subject to a CDSC at the rates set
forth in the following table charged as a percentage of the dollar amount
subject thereto. The charge is assessed on an amount equal to the lesser of the
then current market value or the cost of the shares being redeemed. Accordingly,
no sales charge is imposed on increases in net asset value above the initial
purchase price. In addition, no charge is assessed on shares derived from
reinvestment of dividends or capital gains distributions. It is presently the
policy of the Distributor not to accept any order for Class B shares in an
amount of $500,000 or more because it ordinarily will be more advantageous for
an investor making such an investment to purchase Class A shares.
 
                                       23
<PAGE>   24
 
  The amount of the CDSC, if any, varies depending on the number of years from
the time of payment for the purchase of Class B shares until the time of
redemption of such shares. Solely for purposes of determining the number of
years from the time of any payment for the purchases of shares, all payments
during a month are aggregated and deemed to have been made on the last day of
the month.
- --------------------------------------------------------------------------------
 
<TABLE>
<CAPTION>
                                                             CONTINGENT DEFERRED
                                                              SALES CHARGE AS A
                                                                PERCENTAGE OF
                                                                DOLLAR AMOUNT
                    YEAR SINCE PURCHASE                       SUBJECT TO CHARGE
- --------------------------------------------------------------------------------
<S>                                                          <C>
     First..................................................        4.00%
     Second.................................................        4.00%
     Third..................................................        3.00%
     Fourth.................................................        2.50%
     Fifth..................................................        1.50%
     Sixth and After........................................        None
</TABLE>
 
- --------------------------------------------------------------------------------
 
  In determining whether a CDSC is applicable to a redemption, it is assumed
that the redemption is first of any shares in the shareholder's Fund account
that are not subject to a CDSC, second of shares held for over five years and
third of shares held longest during the five-year period.
 
  To provide an example, assume an investor purchased 100 shares at $10 per
share (at a cost of $1,000) and in the second year after purchase, the net asset
value per share is $12 and, during such time, the investor has acquired 10
additional shares upon dividend reinvestment. If at such time the investor makes
his or her first redemption of 50 shares (proceeds of $600), 10 shares will not
be subject to charge because of dividend reinvestment. With respect to the
remaining 40 shares, the charge is applied only to the original cost of $10 per
share and not to the increase in net asset value of $2 per share. Therefore,
$400 of the $600 redemption proceeds is subject to a deferred sales charge at a
rate of 4.00% (the applicable rate in the second year after purchase).
 
  A commission or transaction fee of 4.00% of the purchase amount will be paid
to authorized dealers at the time of purchase. Additionally, the Distributor
may, from time to time, pay additional promotional incentives, in the form of
cash or other compensation, to authorized dealers that sell Class B shares of
the Fund.
 
CLASS C SHARES
 
  Class C shares are offered at net asset value. Class C shares which are
redeemed within the first year of purchase are subject to a CDSC of 1.00%. The
charge is assessed on an amount equal to the lesser of the then current market
value or the cost of the shares being redeemed. Accordingly, no sales charge is
imposed on increases in net asset value above the initial purchase price. In
addition, no charge is assessed on shares derived from reinvestment of dividends
or capital gains distributions. It is presently the policy of the Distributor
not to accept any order in an amount of $1 million or more for Class C shares
because it ordinarily will be more advantageous for an investor making such an
investment to purchase Class A shares.
 
  In determining whether a CDSC is applicable to a redemption, it is assumed
that the redemption is first of any shares in the shareholder's Fund account
that are not subject to a CDSC and second of shares held for more than one year.
 
  A commission or transaction fee of up to 1.00% of the purchase amount will
generally be paid to authorized dealers at the time of purchase. Authorized
dealers also will be paid ongoing commissions and transaction fees of up to
0.75% of the average daily net assets of the Fund's Class C shares generally
annually commencing in the second year after purchase. Additionally, the
Distributor may, from time to time, pay additional promotional incentives, in
the form of cash or other compensation, to authorized dealers that sell Class C
shares of the Fund.
 
                                       24
<PAGE>   25
 
WAIVER OF CONTINGENT DEFERRED SALES CHARGE
 
  The CDSC is waived on redemptions of Class B shares and Class C shares (i)
following the death or disability (as defined in the Code) of a shareholder;
(ii) in connection with required minimum distributions from an IRA or other
retirement plan; (iii) pursuant to the Fund's systematic withdrawal plan but
limited to 12% annually of the initial value of the account; (iv) in
circumstances under which no commission or transaction fee is paid to authorized
dealers at the time of purchase of such shares; and (v) effected pursuant to the
right of the Fund to liquidate a shareholder's account as described herein under
"Redemption of Shares." The CDSC is also waived on redemptions of Class C shares
as it relates to the reinvestment of redemption proceeds in shares of the same
class of the Fund within 180 days after redemption. See the Statement of
Additional Information for further discussion of waiver provisions.
 
- --------------------------------------------------------------------------------
SHAREHOLDER SERVICES
- --------------------------------------------------------------------------------
 
  The Fund offers a number of shareholder services designed to facilitate
investment in its shares at little or no extra cost to the investor. The
following is a description of such services.
 
  INVESTMENT ACCOUNT. Each shareholder has an investment account under which the
investor's shares of the Fund are held by Investor Services, the Fund's transfer
agent. Investor Services performs bookkeeping, data processing and
administrative services related to the maintenance of shareholder accounts.
Except as described in this Prospectus, after each share transaction in an
account, the shareholder receives a statement showing the activity in the
account. Each shareholder who has an account in any of the Participating Funds
will receive statements quarterly from Investor Services showing any
reinvestments of dividends and capital gains distributions and any other
activity in the account since the preceding statement. Such shareholders also
will receive separate confirmations for each purchase or sale transaction other
than reinvestment of dividends and capital gains distributions and systematic
purchases or redemptions. Additions to an investment account may be made at any
time by purchasing shares through authorized dealers or by mailing a check
directly to Investor Services.
 
  SHARE CERTIFICATES. Generally, the Fund will not issue share certificates.
However, upon written or telephone request to the Fund, a share certificate will
be issued representing shares (with the exception of fractional shares) of the
Fund. A shareholder will be required to surrender such certificates upon
redemption thereof. In addition, if such certificates are lost the shareholder
must write to Van Kampen Funds, c/o Van Kampen Investor Services Inc., P.O. Box
418256, Kansas City, MO 64141-9256, requesting an "affidavit of loss" and obtain
a Surety Bond in a form acceptable to Investor Services. On the date the letter
is received, Investor Services will calculate a fee for replacing the lost
certificate equal to no more than 2.00% of the net asset value of the issued
shares, and bill the party to whom the replacement certificate was mailed.
 
  REINVESTMENT PLAN. A convenient way for investors to accumulate additional
shares is by accepting dividends and capital gains distributions in shares of
the Fund. Such shares are acquired at net asset value (without sales charge) on
the record date. Unless the shareholder instructs otherwise, the reinvestment
plan is automatic. This instruction may be made by telephone by calling (800)
421-5666 ((800) 421-2833 for the hearing impaired) or in writing to Investor
Services. The investor may, on the initial application or prior to any
declaration, instruct that dividends be paid in cash and capital gains
distributions be reinvested at net asset value, or that both dividends and
capital gains distributions be paid in cash.
 
  AUTOMATIC INVESTMENT PLAN. An automatic investment plan is available under
which a shareholder can authorize Investor Services to charge a bank account on
a regular basis to invest predetermined amounts in the Fund. Additional
information is available from the Distributor or authorized investment dealers.
 
  RETIREMENT PLANS. Eligible investors may establish individual retirement
accounts ("IRAs"); SEP; 401(k) plans; Section 403(b)(7) plans in the case of
employees of public school systems and certain non-profit organizations; or
other pension or profit sharing plans. Documents and forms containing detailed
information regarding these plans are available from the Distributor. Van Kampen
Trust Company serves as custodian under the IRA, 403(b)(7) and Keogh plans.
Details regarding fees, as well as full plan administration for profit sharing,
pension and 401(k) plans are available from the Distributor.
 
  AUTOMATED CLEARING HOUSE ("ACH") DEPOSITS.  Holders of Class A shares can use
ACH to have redemption proceeds deposited electronically into their bank
accounts. Redemptions transferred to a bank account via the ACH plan are
 
                                       25
<PAGE>   26
 
available to be credited to the account on the second business day following
normal payment. In order to utilize this option, the shareholder's bank must be
a member of ACH. In addition, the shareholder must fill out the appropriate
section of the account application. The shareholder must also include a voided
check or deposit slip from the bank account into which redemptions are to be
deposited together with the completed application. Once Investor Services has
received the application and the voided check or deposit slip, such
shareholder's designated bank account, following any redemption, will be
credited with the proceeds of such redemption. Once enrolled in the ACH plan, a
shareholder may terminate participation at any time by writing Investor
Services.
 
  DIVIDEND DIVERSIFICATION. A shareholder may, upon written request or by
completing the appropriate section of the application form accompanying this
Prospectus, or by calling (800) 421-5666 ((800) 421-2833 for the hearing
impaired), elect to have all dividends and other distributions paid on a class
of shares of the Fund invested into shares of the same class of any
Participating Fund so long as the shareholder has a pre-existing account for
such class of shares of the other fund. Both accounts must be of the same type,
either non-retirement or retirement. If the accounts are retirement accounts,
they must both be for the same class and of the same type of retirement plan
(e.g. IRA, 403(b)(7), 401(k), Keogh) and for the benefit of the same individual.
If a qualified, pre-existing account does not exist, the shareholder must
establish a new account subject to minimum investment and other requirements of
the fund into which distributions would be invested. Distributions are invested
into the selected fund at its net asset value as of the payable date of the
distribution.
 
  EXCHANGE PRIVILEGE. Shares of the Fund may be exchanged for shares of the same
class of any Participating Fund based on the next computed net asset values of
each fund after requesting the exchange without any sales charge, subject to
certain limitations. Shares of the Fund may be exchanged for shares of any
Participating Fund only if shares of that Participating Fund are available for
sale; however, during periods of suspension of sales, shares of a Participating
Fund may be available for sale only to existing shareholders of a Participating
Fund. Shareholders seeking an exchange into a Participating Fund should obtain
and read the current prospectus for such fund.
 
  To be eligible for exchange, shares of the Fund must have been registered in
the shareholder's name at least 30 days prior to an exchange. Shares of the Fund
registered in a shareholder's name for less than 30 days may only be exchanged
upon receipt of prior approval of the Adviser. Under normal circumstances, it is
the policy of the Adviser not to approve such requests.
 
  When Class B shares and Class C shares are exchanged among Participating
Funds, the holding period for purposes of computing the CDSC is based upon the
date of the initial purchase of such shares from a Participating Fund (the
"original fund"). Upon redemption from the Participating Funds' complex of
funds, Class B shares and Class C share are subject to the CDSC schedule imposed
by the original fund.
 
  Exchanges of shares are sales and may result in a gain or loss for federal
income tax purposes. If the shares exchanged have been held for less than 91
days, the sales charge paid on such shares is carried over and included in the
tax basis of the shares acquired.
 
  A shareholder wishing to make an exchange may do so by sending a written
request to Investor Services or by contacting the telephone transaction line at
(800) 421-5684. A shareholder automatically has telephone exchange privileges
unless otherwise designated in the application form accompanying this
Prospectus. Van Kampen and its subsidiaries, including Investor Services
(collectively, "VK"), and the Fund employ procedures considered by them to be
reasonable to confirm that instructions communicated by telephone are genuine.
Such procedures include requiring certain personal identification information
prior to acting upon telephone instructions, tape recording telephone
communications, and providing written confirmation of instructions communicated
by telephone. If reasonable procedures are employed, neither VK nor the Fund
will be liable for following telephone instructions which it reasonably believes
to be genuine. VK and the Fund may be liable for any losses due to unauthorized
or fraudulent instructions if reasonable procedures are not followed. If the
exchanging shareholder does not have an account in the fund whose shares are
being acquired, a new account will be established with the same registration,
dividend and capital gains options (except dividend diversification) and
authorized dealer of record as the account from which shares are exchanged,
unless otherwise specified by the shareholder. In order to establish a
systematic withdrawal plan for the new account or reinvest dividends from the
new account into another fund, however, an exchanging shareholder must file a
specific written request. The Fund reserves the right to reject any order to
acquire its shares through exchange. In addition, the Fund may modify, restrict
or terminate the exchange privilege at any time on 60 days' notice to its
shareholders of any termination or material amendment.
 
                                       26
<PAGE>   27
 
  A prospectus of any of these mutual funds may be obtained from any authorized
dealer or the Distributor. An investor considering an exchange to one of such
funds should refer to the prospectus for additional information regarding such
fund prior to investing.
 
  SYSTEMATIC WITHDRAWAL PLAN. Any investor whose shares in a single account
total $10,000 or more at the offering price next computed after receipt of
instructions may establish a monthly, quarterly, semi-annual or annual
withdrawal plan. Any investor whose shares in a single account total $5,000 or
more at the offering price next computed after receipt of instructions may
establish a quarterly, semi-annual or annual withdrawal plan. This plan provides
for the orderly use of the entire account, not only the income but also the
capital, if necessary. Each withdrawal constitutes a redemption of shares on
which any capital gain or loss will be recognized. The planholder may arrange
for monthly, quarterly, semi-annual, or annual checks in any amount not less
than $25. Such a systematic withdrawal plan may also be maintained by an
investor purchasing shares for a retirement plan established on a form made
available by the Fund. See "Shareholder Services -- Retirement Plans."
 
  Class B shareholders and Class C shareholders who establish a withdrawal plan
may redeem up to 12% annually of the shareholder's initial account balance
without incurring a CDSC. Initial account balance means the amount of the
shareholder's investment at the time the election to participate in the plan is
made.
 
  Under the plan, sufficient shares of the Fund are redeemed to provide the
amount of the periodic withdrawal payment. Dividends and capital gains
distributions on shares held under the plan are reinvested in additional shares
at the next determined net asset value. If periodic withdrawals continuously
exceed reinvested dividends and capital gains distributions, the shareholder's
original investment will be correspondingly reduced and ultimately exhausted.
Withdrawals made concurrently with the purchase of additional shares ordinarily
will be disadvantageous to the shareholder because of the duplication of sales
charges. Any gain or loss realized by the shareholder upon redemption of shares
is a taxable event.
 
  CHECK WRITING PRIVILEGE. A Class A shareholder holding shares of the Fund for
which certificates have not been issued and which are in a non-escrow status may
appoint Investor Services as agent by completing the Authorization For
Redemption By Check form and the appropriate section of the application and
returning the form and the application to Investor Services. Once the form is
properly completed, signed and returned to the agent, a supply of checks drawn
on State Street Bank and Trust Company (the "Bank") will be sent to the Class A
shareholder. These checks may be made payable by the shareholder to the order of
any person in any amount of $100 or more.
 
  When a check is presented to the Bank for payment, full and fractional Class A
shares required to cover the amount of the check are redeemed from the
shareholder's Class A account by Investor Services at the next determined net
asset value. Check writing redemptions represent the sale of Class A shares. Any
gain or loss realized on the sale of shares is a taxable event. See "Redemption
of Shares."
 
  Checks will not be honored for redemption of Class A shares held less than 15
calendar days, unless such Class A shares have been paid for by bank wire. Any
Class A shares for which there are outstanding certificates may not be redeemed
by check. If the amount of the check is greater than the proceeds of all
uncertificated shares held in the shareholder's Class A account, the check will
be returned and the shareholder may be subject to additional charges. A Class A
shareholder may not liquidate the entire account by means of a check. The check
writing privilege may be terminated or suspended at any time by the Fund or the
Bank. Retirement plans and accounts that are subject to backup withholding are
not eligible for the privilege. A "stop payment" system is not available on
these checks. See the Statement of Additional Information for further
information regarding the establishment of the privilege.
 
  INTERNET TRANSACTIONS. In addition to performing transactions on your account
through written instruction or by telephone, you may also perform certain
transactions through the internet. Please refer to our web site at www.van-
kampen.com for further instruction. VK and the Fund employ procedures considered
by them to be reasonable to confirm that instructions communicated through the
internet are genuine. Such procedures include requiring use of a personal
identification number prior to acting upon internet instructions and providing
written confirmation of instructions communicated through the internet. If
reasonable procedures are employed, neither VK nor the Fund will be liable for
following instructions through the internet which it reasonably believes to be
genuine. If an account has multiple owners, Investor Services may rely on the
instructions of any one owner.
 
                                       27
<PAGE>   28
 
- --------------------------------------------------------------------------------
REDEMPTION OF SHARES
- --------------------------------------------------------------------------------
 
  REGULAR REDEMPTIONS. Shareholders may redeem for cash some or all of their
shares of the Fund at any time. To do so, a written request in proper form must
be sent directly to Van Kampen Investor Services Inc., P.O. Box 418256, Kansas
City, Missouri 64141-9256. Shareholders may also place redemption requests
through an authorized dealer. Orders received from authorized dealers must be at
least $500 unless transmitted via the FUNDSERV network. The redemption price for
such shares is the net asset value next calculated after an order is received by
an authorized dealer provided such order is transmitted to the Distributor prior
to the Distributor's close of business on such day. It is the responsibility of
authorized dealers to transmit redemption requests received by them to the
Distributor so they will be received prior to such time.
 
  As described herein under "Purchase of Shares," redemptions of Class B shares
and Class C shares are subject to a CDSC. In addition, a CDSC of 1.00% may be
imposed on certain redemptions of Class A shares made within one year of
purchase for investments of $1 million or more. The CDSC incurred upon
redemption is paid to the Distributor in reimbursement for distribution-related
expenses. A custodian of a retirement plan account may charge fees based on the
custodian's fee schedule.
 
  The request for redemption must be signed by all persons in whose names the
shares are registered. Signatures must conform exactly to the account
registration. If the proceeds of the redemption exceed $50,000, or if the
proceeds are not to be paid to the record owner at the record address, or if the
record address has changed within the previous 30 days, signature(s) must be
guaranteed by one of the following: a bank or trust company; a broker-dealer; a
credit union; a national securities exchange, registered securities association
or clearing agency; a savings and loan association; or a federal savings bank.
 
  Generally, a properly signed written request with any required signature
guarantee is all that is required for a redemption. In some cases, however,
other documents may be necessary. For example, although the Fund normally does
not issue certificates for shares, it will do so if a special request has been
made to Investor Services. In the case of shareholders holding certificates, the
certificates for the shares being redeemed must accompany the redemption
request. In the event the redemption is requested by a corporation, partnership,
trust, fiduciary, executor or administrator, and the name and title of the
individual(s) authorizing such redemption is not shown in the account
registration, a copy of the corporate resolution or other legal documentation
appointing the authorized signer and certified within the prior 120 days must
accompany the redemption request. IRA redemption requests should be sent to the
IRA custodian to be forwarded to Investor Services. Where Van Kampen Trust
Company serves as custodian, special IRA, 403(b)(7), or Keogh distribution forms
must be obtained from and be forwarded to Van Kampen Trust Company, P.O. Box
944, Houston, Texas 77001-0944. Contact the custodian for information.
 
  In the case of redemption requests sent directly to Investor Services, the
redemption price is the net asset value per share next determined after the
request is received. Payment for shares redeemed will be made by check mailed
within seven days after acceptance by Investor Services of the request and any
other necessary documents in proper order. Such payment may be postponed or the
right of redemption suspended as provided by the rules of the SEC. If the shares
to be redeemed have been recently purchased by check, Investor Services may
delay mailing a redemption check until it confirms that the purchase check has
cleared, which may take up to 15 days. A taxable gain or loss will be recognized
by the shareholder upon redemption of shares.
 
  TELEPHONE REDEMPTIONS. In addition to the regular redemption procedures set
forth above, the Fund permits redemption of shares by telephone and for
redemption proceeds to be sent to the address of record for the account or to
the bank account of record as described below. To establish such privilege, a
shareholder must complete the appropriate section of the application
accompanying this Prospectus or call the Fund at (800) 421-5666 to request that
a copy of the Telephone Redemption Authorization form be sent to them for
completion. To redeem shares contact the telephone transaction line at (800)
421-5684. VK and the Fund employ procedures considered by them to be reasonable
to confirm that instructions communicated by telephone are genuine. Such
procedures include requiring certain personal identification information prior
to acting upon telephone instructions, tape recording telephone communications
and providing written confirmation of instructions communicated by telephone. If
reasonable procedures are employed, neither VK nor the Fund will be liable for
following telephone instructions which it reasonably believes to be genuine. VK
and the Fund may be liable for any losses due to unauthorized or fraudulent
instructions if reasonable procedures are not followed.
 
                                       28
<PAGE>   29
 
Telephone redemptions may not be available if the shareholder cannot reach
Investor Services by telephone, whether because all telephone lines are busy or
for any other reason; in such case, a shareholder would have to use the Fund's
regular redemption procedure previously described. Requests received by Investor
Services prior to 4:00 p.m., New York time, on a regular business day will be
processed at the net asset value per share determined that day. These privileges
are available for all accounts other than retirement accounts. The telephone
redemption privilege is not available for shares represented by certificates. If
an account has multiple owners, Investor Services may rely on the instructions
of any one owner.
 
  For redemptions authorized by telephone, amounts of $50,000 or less may be
redeemed daily if the proceeds are to be paid by check and amounts of at least
$1,000 up to $1 million may be redeemed daily if the proceeds are to be paid by
wire. The proceeds must be payable to the shareholder(s) of record and sent to
the address of record for the account or wired directly to their predesignated
bank account. This privilege is not available if the address of record has been
changed within 30 days prior to a telephone redemption request. Proceeds from
redemptions are expected to be wired on the next business day following the date
of redemption. This service is also not available with respect to shares held in
an individual retirement account (IRA) for which Van Kampen Trust Company acts
as custodian. The Fund reserves the right at any time to terminate, limit or
otherwise modify this redemption privilege.
 
  GENERAL REDEMPTION INFORMATION. The Fund may redeem any shareholder account
with a net asset value on the date of the notice of redemption less than the
minimum initial investment as specified in this Prospectus. At least 60 days
advance written notice of any such involuntary redemption is required and the
shareholder is given an opportunity to purchase the required value of additional
shares at the next determined net asset value without sales charge. Any
involuntary redemption may only occur if the shareholder account is less than
the minimum initial investment due to shareholder redemptions.
 
  REDEMPTION UPON DISABILITY. The Fund will waive the CDSC on redemptions
following the disability of a Class B shareholder or Class C shareholder. An
individual will be considered disabled for this purpose if he or she meets the
definition thereof in Section 72(m)(7) of the Code, which in pertinent part
defines a person as disabled if such person "is unable to engage in any
substantial gainful activity by reason of any medically determinable physical or
mental impairment which can be expected to result in death or to be of
long-continued and indefinite duration." While the Fund does not specifically
adopt the balance of the Code's definition which pertains to furnishing the
Secretary of Treasury with such proof as he or she may require, the Distributor
will require satisfactory proof of disability before it determines to waive the
CDSC on Class B shares and Class C shares.
 
  In cases of disability, the CDSC on Class B shares and Class C shares will be
waived where the disabled person is either an individual shareholder or owns the
shares as a joint tenant with right of survivorship or is the beneficial owner
of a custodial or fiduciary account, and where the redemption is made within one
year of the initial determination of disability. This waiver of the CDSC on
Class B shares and Class C shares applies to a total or partial redemption, but
only to redemptions of shares held at the time of the initial determination of
disability.
 
  REINSTATEMENT PRIVILEGE. A Class A shareholder or Class B shareholder who has
redeemed shares of the Fund may reinstate any portion or all of the net proceeds
of such redemption in Class A shares of the Fund. A Class C shareholder who has
redeemed shares of the Fund may reinstate any portion or all of the net proceeds
of such redemption in Class C shares of the Fund with credit given for any CDSC
paid upon such redemption. Such reinstatement is made at the net asset value
(without sales charge except as described under "Shareholder
Services -- Exchange Privilege") next determined after the order is received,
which must be within 180 days after the date of the redemption. Reinstatement at
net asset value is also offered to participants in those eligible retirement
plans held or administered by Van Kampen Trust Company for repayment of
principal (and interest) on their borrowings on such plans.
 
- --------------------------------------------------------------------------------
DISTRIBUTION AND SERVICE PLANS
- --------------------------------------------------------------------------------
 
  The Fund has adopted a distribution plan (the "Distribution Plan") with
respect to each class of its shares pursuant to Rule 12b-1 under the 1940 Act.
The Fund also has adopted a service plan (the "Service Plan") with respect to
each class of its shares. The Distribution Plan and the Service Plan provide
that the Fund may spend a portion of the Fund's average daily net assets
attributable to each class of shares in connection with distribution of the
respective class of shares and in connection with the provision of ongoing
services to shareholders of each class. The Distribution Plan and the Service
Plan
 
                                       29
<PAGE>   30
 
are being implemented through an agreement with the Distributor and
sub-agreements between the Distributor and brokers, dealers or financial
intermediaries (collectively, "Selling Agreements") that may provide for their
customers or clients certain services or assistance.
 
  CLASS A SHARES. The Fund may spend an aggregate amount up to 0.25% per year of
the average daily net assets attributable to the Class A shares of the Fund
pursuant to the Distribution Plan and Service Plan. From such amount, the Fund
may spend up to 0.25% per year of the Fund's average daily net assets
attributable to the Class A shares pursuant to the Service Plan in connection
with the ongoing provision of services to holders of such shares by the
Distributor and by brokers, dealers or financial intermediaries and in
connection with the maintenance of such shareholders' accounts. The Fund pays
the Distributor the lesser of the balance of the 0.25% not paid to such brokers,
dealers or financial intermediaries or the amount of the Distributor's actual
distribution-related expense.
 
  CLASS B SHARES. The Fund may spend up to 0.75% per year of the average daily
net assets attributable to the Class B shares of the Fund pursuant to the
Distribution Plan. In addition, the Fund may spend up to 0.25% per year of the
Fund's average daily net assets attributable to the Class B shares pursuant to
the Service Plan in connection with the ongoing provision of services to holders
of such shares by the Distributor and by brokers, dealers or financial
intermediaries and in connection with the maintenance of such shareholders'
accounts.
 
  CLASS C SHARES. The Fund may spend up to 0.75% per year of the average daily
net assets attributable to the Class C shares of the Fund pursuant to the
Distribution Plan. From such amount, the Fund, or the Distributor as agent for
the Fund, pays brokers, dealers or financial intermediaries in connection with
the distribution of the Class C shares up to 0.75% of the Fund's average daily
net assets attributable to Class C shares maintained in the Fund more than one
year by such broker's, dealer's or financial intermediary's customers. The Fund
pays the Distributor the lesser of the balance of 0.75% not paid to such
brokers, dealers or financial intermediaries or the amount of the Distributor's
actual distribution-related expense attributable to the Class C shares. In
addition, the Fund may spend up to 0.25% per year of the Fund's average daily
net assets attributable to the Class C shares pursuant to the Service Plan in
connection with the ongoing provision of services to holders of such shares by
the Distributor and by brokers, dealers or financial intermediaries and in
connection with the maintenance of such shareholders' accounts.
 
  OTHER INFORMATION. Amounts payable to the Distributor with respect to the
Class A shares under the Distribution Plan in a given year may not fully
reimburse the Distributor for its actual distribution-related expenses during
such year. In such event, with respect to the Class A shares, there is no
carryover of such reimbursement obligations to succeeding years.
 
  The Distributor's actual expenses with respect to Class B shares or Class C
shares for any given year may exceed the amounts payable to the Distributor with
respect to such class of shares under the Distribution Plan, the Service Plan
and payments received pursuant to the CDSC. In such event, with respect to any
such class of shares, any unreimbursed expenses will be carried forward and paid
by the Fund (up to the amount of the actual expenses incurred) in future years
so long as such Distribution Plan is in effect. Except as mandated by applicable
law, the Fund does not impose any limit with respect to the number of years into
the future that such unreimbursed expenses may be carried forward (on a Fund
level basis). Because such expenses are accounted on a Fund level basis, in
periods of extreme net asset value fluctuation such amounts with respect to a
particular Class B share or Class C share may be greater or less than the amount
of the initial commission (including carrying cost) paid by the Distributor
with respect to such share. In such circumstances, a shareholder of a share may
be deemed to incur expenses attributable to other shareholders of such class. As
of September 30, 1997, there were $16,123,143 and $1,679,724 of unreimbursed
distribution-related expenses with respect to Class B shares and Class C shares,
respectively, representing 13.24% and 12.25% of the Fund's net assets
attributable to Class B shares and Class C shares, respectively. If the
Distribution Plan was terminated or not continued, the Fund would not be
contractually obligated to pay the Distributor for any expenses not previously
reimbursed by the Fund or recovered through CDSCs.
 
  The Distributor will not use the proceeds from the CDSC applicable to a
particular class of shares to defray distribution-related expenses attributable
to any other class of shares. Various federal and state laws prohibit national
banks and some state-chartered commercial banks from underwriting or dealing in
the Fund's shares. In addition, state securities laws on this issue may differ
from the interpretations of federal law, and banks and financial institutions
may be required to register as dealers pursuant to state law. In the unlikely
event that a court were to find that these laws prevent such banks from
providing such services described above, the Fund would seek alternate providers
and expects that shareholders would not experience any disadvantage.
                                       30
<PAGE>   31
 
- --------------------------------------------------------------------------------
DISTRIBUTIONS FROM THE FUND
- --------------------------------------------------------------------------------
 
  DIVIDENDS AND DISTRIBUTIONS. Income dividends are declared each business day,
and distributed monthly. The daily dividend is a fixed amount determined for
each class at least monthly. Shares (other than shares acquired through an
exchange) become entitled to dividends on the day Investor Services receives
payment for the shares. With respect to shares acquired through an exchange,
such shares become entitled to dividends on the day after Investor Services
receives payment for the shares. If a dealer delays forwarding to Investor
Services payment for shares which an investor has made to the dealer, this will
in effect cost the investor money because it will delay the date upon which such
investor becomes entitled to dividends. Shares (other than shares sold through
an exchange) remain entitled to dividends through the day before such shares are
priced for redemption purposes, which occurs when a valid redemption request
with respect to such shares is received by Investor Services. With respect to
shares sold through an exchange, such shares remain entitled to dividends
through and including the day such shares are priced for redemption.
 
  The per share dividends on Class B shares and Class C shares may be lower than
the per share dividends on Class A shares as a result of the higher distribution
fees and transfer agency costs applicable to such classes of shares.
 
  Any net realized short-term or long-term capital gains will be distributed to
shareholders at least annually.
 
  Unless the shareholder instructs otherwise, dividends and capital gains
distributions are automatically applied to purchase additional shares of the
Fund at the next determined net asset value. See "Shareholder
Services -- Reinvestment Plan."
 
  Dividends and distributions paid by the Fund have the effect of reducing the
net asset value per share on the record date by the amount of the dividend or
distribution. Therefore, a dividend or distribution paid shortly after a
purchase of shares by an investor would represent, in substance, a return of
capital to the shareholder (to the extent it is paid on the shares so
purchased), even though it would be subject to income taxes, as discussed below.
 
- --------------------------------------------------------------------------------
TAX STATUS
- --------------------------------------------------------------------------------
 
  FEDERAL INCOME TAXATION.  The Fund has qualified and intends to continue to
qualify each year to be treated as a regulated investment company under
Subchapter M of the Code. To qualify as a regulated investment company, the Fund
must comply with certain requirements of the Code relating to, among other
things, the source of its income and diversification of its assets.
 
  If the Fund so qualifies and distributes each year to its shareholders at
least 90% of its net investment income (including tax-exempt interest, taxable
income and net short-term capital gain, but not net capital gains, which are the
excess of net long-term capital gains over net short-term capital losses), it
will not be required to pay federal income taxes on any income distributed to
shareholders. The Fund intends to distribute at least the minimum amount of net
investment income necessary to satisfy the 90% distribution requirement. The
Fund will not be subject to federal income tax on any net capital gains
distributed to shareholders.
 
  In order to avoid a 4% excise tax, the Fund will be required to distribute, by
December 31 of each year, at least 98% of its ordinary income (not including
tax-exempt income) for such year and at least 98% of its capital gain net income
(the latter of which generally is computed on the basis of the one-year period
ending on October 31 of such year), plus any amounts that were not distributed
in previous taxable years. For purposes of the excise tax, any ordinary income
or capital gain net income retained by, and subject to federal income tax in the
hands of, the Fund will be treated as having been distributed.
 
  If the Fund failed to qualify as a regulated investment company or failed to
satisfy the 90% distribution requirement in any taxable year, the Fund would be
taxed as an ordinary corporation on its taxable income (even if such income were
distributed to its shareholders) and all distributions out of earnings and
profits would be taxed to shareholders as ordinary income. To qualify again as a
regulated investment company in a subsequent year, the Fund may be required to
pay an interest charge on 50% of its earnings and profits attributable to
non-regulated investment company years and would be required to distribute such
earnings and profits to shareholders (less any interest charge). In addition, if
the Fund failed to qualify as a regulated investment company for its first
taxable year or, if immediately after qualifying as a regulated
 
                                       31
<PAGE>   32
 
investment company for any taxable year, it failed to qualify for a period
greater than one taxable year, the Fund would be required to recognize any net
built-in gains (the excess of aggregate gains, including items of income, over
aggregate losses that would have been realized if it had been liquidated) in
order to qualify as a regulated investment company in a subsequent year.
 
  Some of the Fund's investment practices are subject to special provisions of
the Code that, among other things, may defer the use of certain losses of the
Fund and affect the holding period of the securities held by the Fund and the
character of the gains or losses realized by the Fund. These provisions may also
require the Fund to recognize income or gain without receiving cash with which
to make distributions in amounts necessary to satisfy the 90% distribution
requirement and the distribution requirements for avoiding income and excise
taxes. The Fund will monitor its transactions and may make certain tax elections
in order to mitigate the effect of these rules and prevent disqualification of
the Fund as a regulated investment company.
 
  Investments of the Fund in securities issued at a discount or providing for
deferred interest or payment of interest in kind are subject to special tax
rules that will affect the amount, timing and character of distributions to
shareholders. For example, with respect to securities issued at a discount, the
Fund will be required to accrue as income each year a portion of the discount
and to distribute such income each year in order to maintain its qualification
as a regulated investment company and to avoid income and excise taxes. In order
to generate sufficient cash to make distributions necessary to satisfy the 90%
distribution requirement and to avoid income and excise taxes, the Fund may have
to dispose of securities that it would otherwise have continued to hold.
 
  DISTRIBUTIONS.  Distributions of the Fund's net investment income are taxable
to shareholders as ordinary income to the extent of the Fund's earnings and
profits, whether paid in cash or reinvested in additional shares. Distributions
of the Fund's net capital gains ("capital gains dividends"), if any, are taxable
to shareholders as long-term capital gains regardless of the length of time
shares of the Fund have been held by such shareholders. Distributions in excess
of the Fund's earnings and profits will first reduce the adjusted tax basis of a
holder's shares and, after such adjusted tax basis is reduced to zero, will
constitute capital gains to such holder (assuming such shares are held as a
capital asset). For a summary of the tax rates applicable to capital gains
(including capital gain dividends), see "Capital Gains Rates Under the 1997 Tax
Act" below. Tax-exempt shareholders not subject to federal income tax on their
income generally will not be taxed on distributions from the Fund.
 
  Shareholders receiving distributions in the form of additional shares issued
by the Fund will be treated for federal income tax purposes as receiving a
distribution in an amount equal to the fair market value of the shares received,
determined as of the distribution date. The basis of such shares will equal the
fair market value on the distribution date.
 
  The Fund will inform shareholders of the source and tax status of all
distributions promptly after the close of each calendar year. Fund distributions
will not qualify for the dividends received deduction for corporations.
 
  Although dividends generally will be treated as distributed when paid,
dividends declared in October, November or December, payable to shareholders of
record on a specified date in such month and paid during January of the
following year will be treated as having been distributed by the Fund and
received by the shareholders on the December 31 prior to the date of payment. In
addition, certain other distributions made after the close of a taxable year of
the Fund may be "spilled back" and treated as paid by the Fund (except for
purposes of the 4% excise tax) during such taxable year. In such case,
shareholders will be treated as having received such dividends in the taxable
year in which the distribution was actually made.
 
  Income from investments in foreign securities received by the Fund may be
subject to income, withholding or other taxes imposed by foreign countries and
U.S. possessions. Such taxes will not be deductible or creditable by
shareholders. Tax conventions between certain countries and the United States
may reduce or eliminate such taxes.
 
  Under Code Section 988, foreign currency gains or losses from certain forward
contracts not traded in the interbank market as well as certain other gains or
losses attributable to currency exchange rate fluctuations are typically treated
as ordinary income or loss. Such income or loss may increase or decrease (or
possibly eliminate) the Fund's income available for distribution. If, under the
rules governing the tax treatment of foreign currency gains and losses, the
Fund's income available for distribution is decreased or eliminated, all or a
portion of the dividends declared by the Fund may be treated for federal income
tax purposes as a return of capital or, in some circumstances, as capital gain.
Generally, a shareholder's tax basis in Fund shares will be reduced to the
extent that an amount distributed to such shareholder is treated as a return of
capital.
                                       32
<PAGE>   33
 
  The Fund is required, in certain circumstances, to withhold 31% of dividends
and certain other payments, including redemptions, paid to shareholders who do
not furnish to the Fund their correct taxpayer identification number (in the
case of individuals, their social security number) and certain required
certifications or who are otherwise subject to backup withholding.
 
  SALE OF SHARES.  The sale of shares (including transfers in connection with a
redemption or repurchase of shares) will be a taxable transaction for federal
income tax purposes. Selling shareholders will generally recognize gain or loss
in an amount equal to the difference between their adjusted tax basis in the
shares and the amount received. If such shares are held as a capital asset, the
gain or loss will be a capital gain or loss. For a summary of the tax rates
applicable to capital gains, see "Capital Gains Rates Under the 1997 Tax Act"
below. Any loss recognized upon a taxable disposition of shares held for six
months or less will be treated as a long-term capital loss to the extent of any
capital gains dividends received with respect to such shares. For purposes of
determining whether shares have been held for six months or less, the holding
period is suspended for any periods during which the shareholder's risk of loss
is diminished as a result of holding one or more other positions in
substantially similar or related property or through certain options or short
sales.
 
  CAPITAL GAINS RATES UNDER THE 1997 TAX ACT.  Under the Taxpayer Relief Act of
1997 (the "1997 Tax Act"), the maximum tax rates applicable to net capital gains
recognized by individuals and other non-corporate taxpayers are (i) the same as
ordinary income rates for capital assets held for one year or less, (ii) 28% for
capital assets held for more than one year but not more than 18 months and (iii)
20% for capital assets held for more than 18 months. The 1997 Tax Act did not
affect the maximum long-term capital gains rate for corporations which remains
at 35%. The new tax rates for capital gains under the 1997 Tax Act described
above apply to distributions of capital gains dividends by regulated investment
companies such as the Fund as well as to sales and exchanges of shares in
regulated investment companies such as the Fund. With respect to capital losses
recognized on dispositions of shares held six months or less where such losses
are treated as long-term capital losses to the extent of prior capital gains
dividends received on such shares (see "Sale of Shares" above), it is unclear
how such capital losses offset the capital gains referred to above. Shareholders
should consult their own tax advisors as to the application of the new capital
gains rates to their particular circumstances.
 
  GENERAL.  The federal income tax discussion set forth above is for general
information only. Prospective investors should consult their own tax advisor
regarding the specific federal tax consequences of purchasing, holding and
disposing of shares, as well as the effects of state, local and foreign tax law
and any proposed tax law changes.
 
- --------------------------------------------------------------------------------
FUND PERFORMANCE
- --------------------------------------------------------------------------------
 
  From time to time the Fund may advertise its total return for prior periods.
Any such advertisement would include at least average annual total return
quotations for one year, five year and ten year periods. Other total return
quotations, aggregate or average, over other time periods may also be included.
 
  The total return of the Fund for a particular period represents the increase
(or decrease) in the value of a hypothetical investment in the Fund from the
beginning to the end of the period. Total return is calculated by subtracting
the value of the initial investment from the ending value and showing the
difference as a percentage of the initial investment; the calculation assumes
the initial investment is made at the current maximum public offering price
(which includes a maximum sales charge of 4.75% for Class A shares); that all
income dividends or capital gains distributions during the period are reinvested
in Fund shares at net asset value; and that any applicable CDSC has been paid.
The Fund's total return will vary depending on market conditions, the securities
comprising the Fund's portfolio, the Fund's operating expenses and unrealized
net capital gains or losses during the period. Total return is based on
historical earnings and asset value fluctuations and is not intended to indicate
future performance. No adjustments are made to reflect any income taxes payable
by shareholders on dividends and distributions paid by the Fund.
 
  Average annual total return quotations for periods of two or more years are
computed by finding the average annual compounded rate of return over the period
that would equate the initial amount invested to the ending redeemable value.
 
  In addition to total return information, the Fund may also advertise its
current "yield." Yield figures are based on historical earnings and are not
intended to indicate future performance. Yield is determined by analyzing the
Fund's net income per share for a 30-day (or one-month) period (which period
will be stated in the advertisement) and dividing by
 
                                       33
<PAGE>   34
 
the maximum offering price per share on the last day of the period. A "bond
equivalent" annualization method is used to reflect a semiannual compounding.
 
  For purposes of calculating yield quotations, net income is determined by a
standard formula prescribed by the SEC to facilitate comparison with yields
quoted by other investment companies. Net income computed for this formula
differs from net income reported by the Fund in accordance with generally
accepted accounting principles and from net income computed for federal income
tax reporting purposes. Thus the yield computed for a period may be greater or
less than the Fund's then current dividend rate.
 
  The Fund's yield is not fixed and will fluctuate in response to prevailing
interest rates and the market value of portfolio securities, and as a function
of the type of securities owned by the Fund, portfolio maturity and the Fund's
expenses.
 
  Yield quotations should be considered relative to changes in the net asset
value of the Fund's shares, the Fund's investment policies, and the risks of
investing in shares of the Fund. The investment return and principal value of an
investment in the Fund will fluctuate so that an investor's shares, when
redeemed, may be worth more or less than their original cost.
 
  To increase the Fund's yield the Adviser may, from time to time, absorb a
certain amount of the future ordinary business expenses. The Adviser may stop
absorbing these expenses at any time without prior notice.
 
  Yield and total return are calculated separately for Class A shares, Class B
shares and Class C shares. Total return figures for Class A shares include the
maximum sales charge of 4.75%; total return figures for Class B shares and Class
C shares include any applicable CDSC. Because of the differences in sales
charges and distribution fees, the total returns for each of the classes will
differ.
 
  From time to time, the Fund may include in its sales literature and
shareholder reports a quotation of the current "distribution rate" for each
class of shares of the Fund. Distribution rate is a measure of the level of
income and short-term capital gain dividends, if any, distributed for a
specified period. Distribution rate differs from yield, which is a measure of
the income actually earned by the Fund's investments, and from total return
which is a measure of the income actually earned by the Fund's investments plus
the effect of any realized and unrealized appreciation or depreciation of such
investments during a stated period. Distribution rate is, therefore, not
intended to be a complete measure of the Fund's performance. Distribution rate
may sometimes be greater than yield since, for instance, it may not include the
effect of amortization of bond premiums, and may include non-recurring
short-term capital gains and premiums from futures transactions engaged in by
the Fund. Distribution rates will be computed separately for each class of the
Fund's shares.
 
  In reports or other communications to shareholders or in advertising material,
the Fund may compare its performance with that of other mutual funds as listed
in the rankings or ratings prepared by Lipper Analytical Services, Inc., CDA,
Morningstar Mutual Funds or similar independent services which monitor the
performance of mutual funds, with the Consumer Price Index, other appropriate
indices of investment securities, or with investment or savings vehicles. The
performance information may also include evaluations of the Fund published by
nationally recognized ranking services and by nationally recognized financial
publications. Such comparative performance information will be stated in the
same terms in which the comparative data or indices are stated. Such
advertisements and sales material may also include a yield quotation as of a
current period. In each case, such total return and yield information, if any,
will be calculated pursuant to rules established by the SEC and will be computed
separately for each class of the Fund's shares. For these purposes, the
performance of the Fund, as well as the performance of other mutual funds or
indices, do not reflect sales charges, the inclusion of which would reduce
Fund's performance. The Fund will include performance data for each class of
shares of the Fund in any advertisement or information including performance
data of the Fund.
 
  The Fund may also utilize performance information in hypothetical
illustrations provided in narrative form. These hypotheticals will be
accompanied by standard performance information required by the SEC as described
above.
 
  The Fund's Annual Report and Semi-Annual Report contain additional performance
information. A copy of the Annual Report or Semi-Annual Report may be obtained
without charge by calling or writing the Fund at the telephone number and
address printed on the cover of this Prospectus.
 
                                       34
<PAGE>   35
 
- --------------------------------------------------------------------------------
DESCRIPTION OF SHARES OF THE FUND
- --------------------------------------------------------------------------------
 
  The Fund was originally organized on June 24, 1992, under the laws of the
Commonwealth of Massachusetts as a business entity commonly known as a
"Massachusetts business trust". The Fund was reorganized as a Delaware business
trust as of August 5, 1995 and on July 14, 1998 adopted its current name.
 
  The authorized capitalization of the Fund consists of an unlimited number of
shares of beneficial interest, par value $0.01 per share, divided into classes.
The Fund currently offers three classes of shares, designated Class A shares,
Class B shares and Class C shares. Other classes may be established from time to
time in accordance with the provisions of the Fund's Declaration of Trust.
 
  Each class of shares represents an interest in the same assets of the Fund and
generally are identical in all respects except that each class bears certain
distribution expenses and has exclusive voting rights with respect to its
distribution fee. Except as described herein, there are no conversion,
preemptive or other subscription rights. In the event of liquidation, each of
the shares of the Fund is entitled to its portion of all of the Fund's net
assets after all debt and expenses of the Fund have been paid. Since Class B
shares and Class C shares pay higher distribution fees and transfer agency
costs, the liquidation proceeds to Class B shareholders and Class C shareholders
are likely to be lower than to other shareholders.
 
  The Fund does not contemplate holding regular meetings of shareholders to
elect Trustees or otherwise. However, the holders of 10% or more of the
outstanding shares may by written request require a meeting to consider the
removal of Trustees by a vote of two-thirds of the shares then outstanding cast
in person or by proxy at such meeting. The Fund will assist such holders in
communicating with other shareholders of the Fund to the extent required by the
1940 Act. More detailed information concerning the Fund is set forth in the
Statement of Additional Information.
 
  The Fund's Declaration of Trust provides that no Trustee, officer or
shareholder of the Fund shall be held to any personal liability, nor shall
resort be had to their private property for the satisfaction of any obligation
or liability of the Fund but the assets of the Fund only shall be liable.
 
- --------------------------------------------------------------------------------
ADDITIONAL INFORMATION
- --------------------------------------------------------------------------------
 
  This Prospectus and the Statement of Additional Information do not contain all
the information set forth in the Registration Statement filed by the Fund with
the SEC under the Securities Act of 1933. Copies of the Registration Statement
may be obtained at a reasonable charge from the SEC or may be examined, without
charge, at the office of the SEC in Washington, D.C.
 
  The fiscal year end of the Fund is September 30. The Fund sends to its
shareholders at least semi-annually reports showing the Fund's portfolio and
other information. An Annual Report, containing financial statements audited by
the Fund's independent accountants, is sent to shareholders each year. After the
end of each year, shareholders will receive federal tax information regarding
dividends and capital gains distribution.
 
                                       35
<PAGE>   36
 
EXISTING SHAREHOLDERS--
FOR INFORMATION ON YOUR
EXISTING ACCOUNT PLEASE CALL
THE FUND'S TOLL-FREE
NUMBER--(800) 341-2911
 
PROSPECTIVE INVESTORS--CALL
YOUR BROKER OR (800) 421-5666
 
DEALERS--FOR DEALER
INFORMATION, SELLING
AGREEMENTS, WIRE ORDERS,
OR REDEMPTIONS CALL THE
DISTRIBUTOR'S TOLL-FREE
NUMBER--(800) 421-5666
 
FOR SHAREHOLDER AND
DEALER INQUIRIES THROUGH
TELECOMMUNICATIONS
DEVICE FOR THE DEAF (TDD)
DIAL (800) 421-2833
 
FOR AUTOMATED TELEPHONE
SERVICES DIAL (800) 847-2424
 
VAN KAMPEN U.S. GOVERNMENT TRUST
  FOR INCOME
One Parkview Plaza
Oakbrook Terrace, IL 60181
 
Investment Adviser
VAN KAMPEN ASSET MANAGEMENT INC.
One Parkview Plaza
Oakbrook Terrace, IL 60181
Distributor
VAN KAMPEN FUNDS INC.
One Parkview Plaza
Oakbrook Terrace, IL 60181
 
Transfer Agent
VAN KAMPEN INVESTOR SERVICES INC.
P.O. Box 418256
Kansas City, MO 64141-9256
Attn: Van Kampen U.S. Government Trust for Income
Custodian
STATE STREET BANK AND
TRUST COMPANY
225 West Franklin Street
P.O. Box 1713
Boston, MA 02105-1713
Attn: Van Kampen U.S. Government Trust for Income
 
Legal Counsel
SKADDEN, ARPS, SLATE,
MEAGHER & FLOM (Illinois)
333 West Wacker Drive
Chicago, IL 60606
 
Independent Accountants
PRICEWATERHOUSECOOPERS LLP
200 East Randolph Drive
Chicago, IL 60601
<PAGE>   37
 
- --------------------------------------------------------------------------------
 
                                U.S. GOVERNMENT
                                TRUST FOR INCOME
 
- --------------------------------------------------------------------------------
 
       P       R       O      S      P      E      C      T      U      S
 
                      JANUARY 28, 1998, AS SUPPLEMENTED ON
                MARCH 9, 1998, JULY 14, 1998 AND OCTOBER 1, 1998
 
                             VAN KAMPEN FUNDS LOGO
 
                                                                   GTI PRO 10/98


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