FORM OF
                                INVESTMENT LETTER

                       SELIGMAN CASH MANAGEMENT FUND, INC.

Seligman Cash Management Fund, Inc. (the "Fund"), an open-end diversified
management investment company, and the undersigned ("Purchaser"), intending to
be legally bound, hereby agree as follows:

1.    The Fund hereby sells to Purchaser and Purchaser purchases such number of
      Class R shares (the "Shares") of Capital Stock (par value $.01) of the
      Fund corresponding to a $1,000.00 investment, at a price per share
      equivalent to the net asset value of one Class A share of the Fund as of
      the close of business on _______________, 2003 (the "Purchase Date"). The
      Fund hereby acknowledges receipt from Purchaser of funds in the amount of
      $1,000.000 in full payment for the Shares.

2.    Purchaser represents and warrants to the Fund that the Shares are being
      acquired for investment and not with a view to distribution thereof, and
      that Purchaser has no present intention to redeem or dispose of the
      Shares.

IN WITNESS WHEREOF, the parties have executed this agreement as of the Purchase
Date.

                                    SELIGMAN CASH MANAGEMENT FUND, INC.

                                    By:
                                       -----------------------------------------
                                    Name:  Lawrence P. Vogel
                                    Title: Vice President


                                    SELIGMAN ADVISORS, INC.

                                    By:
                                       -----------------------------------------
                                    Name:  Stephen J. Hodgdon
                                    Title: President