19 CFR § 10.2011 - Filing procedures.
(a)Place of filing. A post-importation claim for a refund must be filed with CBP, either at the port of entry or electronically. The post-importation claim may be filed by paper or by the method specified for equivalent reporting via an authorized electronic data interchange system.
(b)Contents of claim. A post-importation claim for a refund must be filed by presentation of the following:
(1) A written or electronic declaration or statement stating that the good was an originating good at the time of importation and setting forth the number and date of the entry or entries covering the good;
(2) A copy of a written or electronic certification prepared in accordance with § 10.2004 if a certification forms the basis for the claim, or other information demonstrating that the good qualifies for preferential tariff treatment;
(3) A written statement indicating whether the importer of the good provided a copy of the entry summary or equivalent documentation to any other person. If such documentation was so provided, the statement must identify each recipient by name, CBP identification number, and address and must specify the date on which the documentation was provided; and
(4) A written statement indicating whether any person has filed a protest relating to the good under any provision of law; and if any such protest has been filed, the statement must identify the protest by number and date.