You do not require a formal Nafta Certificate of Origin for a commercial importation of a good whose value does not exceed US$2,500, provided that, unless waived by the port director, the producer, exporter, importer or authorized agent includes on, or attaches to, the invoice or other document accompanying the shipment the attached signed statement.
Note:
If the port director determines that an importation described in the paragraph above forms part of a series of importations that may reasonably be considered to have been undertaken or arranged for the purpose of avoiding a certification requirement set forth in this part, the port director shall notify the importer in writing that for that importation the importer must have in his possession a valid Certificate of Origin to support the claim for preferential tariff treatment. The importer shall have 30 calendar days from the date of the written notice to obtain a valid Certificate, and a failure to timely obtain the Certificate will result in denial of the claim for preferential tariff treatment. A “series of importations” means two or more entries covering goods arriving on the same day from the same exporter and consigned to the same person.