Exhibit 99.1350CERT


     Certification Pursuant to Section 906 of the Sarbanes Oxley Act


I, Robert C. Doll, Jr., Chief Executive Officer of CMA Tax-Exempt Fund and
Master Tax-Exempt Trust (together, the "Fund"), certify that:

1. The N-CSR of the Fund (the "Report") fully complies with the requirements
   of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material
   respects, the financial condition and results of operations of the Fund.


Dated: November 17, 2005


                                         /s/ Robert C. Doll, Jr.
                                         -----------------------
                                         Robert C. Doll, Jr.,
                                         Chief Executive Officer of
                                         CMA Tax-Exempt Fund and
                                         Master Tax-Exempt Trust


A signed original of this written statement required by Section 906, or other
document authenticating, acknowledging, or otherwise adopting the signature
that appears in typed form within the electronic version of this written
statement required by Section 906, has been provided to CMA Tax-Exempt Fund and
Master Tax-Exempt Trust and will be retained by CMA Tax-Exempt Fund and Master
Tax-Exempt Trust and furnished to the Securities and Exchange Commission or its
staff upon request.



Exhibit 99.1350CERT


     Certification Pursuant to Section 906 of the Sarbanes Oxley Act


I, Donald C. Burke, Chief Financial Officer of CMA Tax-Exempt Fund and Master
Tax-Exempt Trust (together, the "Fund"), certify that:

1. The N-CSR of the Fund (the "Report") fully complies with the requirements
   of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and

2. The information contained in the Report fairly presents, in all material
   respects, the financial condition and results of operations of the Fund.


Dated: November 17, 2005


                                         /s/ Donald C. Burke
                                         --------------------
                                         Donald C. Burke,
                                         Chief Financial Officer of
                                         CMA Tax-Exempt Fund and
                                         Master Tax-Exempt Trust


A signed original of this written statement required by Section 906, or other
document authenticating, acknowledging, or otherwise adopting the signature
that appears in typed form within the electronic version of this written
statement required by Section 906, has been provided to CMA Tax-Exempt Fund and
Master Tax-Exempt Trust and will be retained by CMA Tax-Exempt Fund and Master
Tax-Exempt Trust and furnished to the Securities and Exchange Commission or its
staff upon request.