19 CFR § 181.11 - Certificate of Origin.
(a) General. A Certificate of Origin shall be employed to certify that a good being exported either from the United States into Canada or Mexico or from Canada or Mexico into the United States qualifies as an originating good for purposes of preferential tariff treatment under the NAFTA.
(b) Preparation of Certificate in the United States. An exporter in the United States who completes and signs a Certificate of Origin for the purpose set forth in paragraph (a) of this section shall use Customs Form 434, or its electronic equivalent or such other medium or format as approved by the Canadian or Mexican customs administration for that purpose. Where the U.S. exporter is not the producer of the good, that exporter may complete and sign a Certificate on the basis of:
(1) Its knowledge of whether the good qualifies as an originating good;
(c) Submission of Certificate to Customs. An exporter in the United States, and a producer in the United States who has voluntarily provided a copy of a Certificate of Origin to that exporter pursuant to paragraph (b)(3) of this section, shall provide a copy of the Certificate to Customs upon request.
(d) Notification of errors in Certificate. An exporter or producer in the United States who has completed and signed a Certificate of Origin, and who has reason to believe that the Certificate contains information that is not correct, shall within 30 calendar days after the date of discovery of the error notify in writing all persons to whom the Certificate was given by the exporter or producer of any change that could affect the accuracy or validity of the Certificate.