VAN KAMPEN UNIT TRUSTS, MUNICIPAL SERIES 531, 532, 534,
                         535, 536, 537, 538, 539 AND 540

                          SUPPLEMENT TO THE PROSPECTUS

         PUBLIC OFFERING--UNIT DISTRIBUTION. The paragraph immediately following
the table under "Public Offering--Unit Distribution--IM-IT Laddered Series and
IM-IT Limited Maturity Trusts" in Prospectus Part II is replaced in its entirety
with the following paragraph:

                  Notwithstanding the preceding table, non-Underwriter
         broker-dealers and other selling agents that purchase 100 or more Units
         of a Trust from the Sponsor on the Date of Deposit ("Qualifying
         Broker-Dealers") will be allowed a concession or agency commission on
         such Units equal to the regular concession allowed to Underwriters
         described under "Sponsor and Underwriter Compensation" below. In
         addition, Qualifying Broker-Dealers will be allowed a concession or
         agency commission equal to $27 per Unit on subsequent Unit purchases
         from the Sponsor throughout the remainder of the initial offering
         period, provided, however, that a Qualifying Broker-Dealer will be
         allowed a concession or agency commission equal to the concession or
         agency commission allowed to such firm on the Date of Deposit for
         subsequent purchases on a single day equal to the lesser of (a) 1,000
         Units of a Trust (or all remaining Units if the Sponsor has less than
         1,000 unsold Units available for sale) or (b) the number of Units of a
         Trust purchased on the Date of Deposit.

         The paragraph immediately following the table under "Public
Offering--Unit Distribution--IM-IT Laddered Series and IM-IT Limited Maturity
Trusts" in Prospectus Part II is replaced in its entirety with the following
paragraph:

                  Notwithstanding the preceding table, non-Underwriter
         broker-dealers and other selling agents that purchase 100 or more Units
         of a Long-Term Trust from the Sponsor on the Date of Deposit
         ("Qualifying Broker-Dealers") will be allowed a concession or agency
         commission on such Units equal to the regular concession allowed to
         Underwriters described under "Sponsor and Underwriter Compensation"
         below. In addition, Qualifying Broker- Dealers will be allowed a
         concession or agency commission equal to $35 per Unit on subsequent
         Unit purchases from the Sponsor throughout the remainder of the initial
         offering period, provided, however, that a Qualifying Broker-Dealer
         will be allowed a concession or agency commission equal to the
         concession or agency commission allowed to such firm on the Date of
         Deposit for subsequent purchases on a single day equal to the lesser of
         (a) 1,000 Units of a Trust (or all remaining Units if the Sponsor has
         less than 1,000 unsold Units available for sale) or (b) the number of
         Units of a Trust purchased on the Date of Deposit.

         PUBLIC OFFERING--SPONSOR AND UNDERWRITER COMPENSATION. The paragraph
immediately following the table under "Public Offering--Sponsor and Underwriter
Compensation--Long-Term Trusts" in Prospectus Part II is replaced in its
entirety with the following paragraph:

                  In addition, Underwriters of these Trusts will be allowed a
         concession or agency commission equal to $27 per Unit on subsequent
         Unit purchases throughout the remainder of the initial offering period
         rather than the broker-dealer concessions described under "Unit
         Distribution," provided, however, that an Underwriter will be allowed a
         concession equal to the Underwriter concession allowed to such firm on
         the Date of Deposit for subsequent purchases on a single day equal to
         the lesser of (a) 1,000 Units of a Trust (or all remaining Units if the
         Sponsor has less than 1,000 unsold Units available for sale) or (b) the
         number of Units of a Trust purchased on the Date of Deposit.

         The paragraph immediately following the table under "Public
Offering--Sponsor and Underwriter Compensation--Long-Term Trusts" in Prospectus
Part II is replaced in its entirety with the following paragraph:

                  In addition, Underwriters of a Long-Term Trust will be allowed
         a concession or agency commission equal to $35 per Unit on subsequent
         Unit purchases throughout the remainder of the initial offering period
         rather than the broker-dealer concessions described under "Unit
         Distribution," provided, however, that an Underwriter will be allowed a
         concession equal to the Underwriter concession allowed to such firm on
         the Date of Deposit for subsequent purchases on a single day equal to
         the lesser of (a) 1,000 Units of a Trust (or all remaining Units if the
         Sponsor has less than 1,000 unsold Units available for sale) or (b) the
         number of Units of a Trust purchased on the Date of Deposit.

Supplement Dated:  December 21, 2004