# 181.21 Filing of claim for preferential tariff treatment upon importation.
(a) *Declaration.* In connection with a claim for preferential tariff treatment, or for the exemption from the merchandise processing fee, for a good under the NAFTA, the U.S. importer must make a formal declaration that the good qualifies for such treatment. The declaration may be made by including on the entry summary, or equivalent documentation, including electronic submissions, the symbol “CA” for a good of Canada, or the symbol “MX” for a good of Mexico, as a prefix to the subheading of the HTSUS under which each qualifying good is classified. Except as otherwise provided in 19 CFR 181.22 and except in the case of a good to which Appendix 6.B to Annex 300-B of the NAFTA applies (see also 19 CFR 102.25), the declaration must be based on a complete and properly executed original Certificate of Origin, or copy thereof, which is in the possession of the importer and which covers the good being imported.
(b) *Corrected declaration.* If, after making the declaration required under paragraph (a) of this section or under § 181.32(b)(2) of this part, the U.S. importer has reason to believe that a Certificate of Origin on which a declaration was based contains information that is not correct, the importer shall within 30 calendar days after the date of discovery of the error make a corrected declaration and pay any duties that may be due. A corrected declaration shall be effected by submission of a letter or other written statement to the CBP office where the original declaration was filed.
[T.D. 95-68, 60 FR 46364, Sept. 6, 1995, as amended by CBP Dec. 07-76, 72 FR 52782, Sept. 17, 2007]