<Page>

                                                             Exhibit 99.CERT.906

FORM N-CSR ITEM 11(b) EXHIBIT

                            CERTIFICATION PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

          The undersigned hereby certify in their capacity as Treasurer and
President, respectively, of North Carolina Municipals Portfolio (the
"Portfolio"), that:

  (a)  the Semi-Annual Report of the Portfolio on Form N-CSR for the period
       ended February 29, 2004 (the "Report") fully complies with the
       requirements of Section 13(a) or 15(d) of the Securities Exchange Act of
       1934, as amended; and

  (b)  the information contained in the Report fairly presents, in all material
       respects, the financial condition and the results of operations of the
       Portfolio for such period.

A SIGNED ORIGINAL OF THIS WRITTEN STATEMENT REQUIRED BY SECTION 906 HAS BEEN
PROVIDED TO THE PORTFOLIO AND WILL BE RETAINED BY THE PORTFOLIO AND FURNISHED TO
THE SECURITIES AND EXCHANGE COMMISSION OR ITS STAFF UPON REQUEST.

Date: April 20, 2004
      --------------


 /s/ Barbara E. Campbell
- ---------------------------------------
Barbara E. Campbell
Treasurer

Date: April 20, 2004
      --------------


 /s/ Thomas J. Fetter
- ---------------------------------------
Thomas J. Fetter
President