19 CFR § 10.441 - Filing procedures.
(a) Place of filing. A post-importation claim for a refund under § 10.440 of this subpart must be filed with CBP, either at the port of entry or electronically.
(b) Contents of claim. A post-importation claim for a refund must be filed by presentation of the following:
(1) A written declaration stating that the good qualified as an originating good at the time of importation and setting forth the number and date of the entry or entries covering the good;
(2) Subject to § 10.413 of this subpart, a copy of a certification of origin or other information demonstrating that the good qualifies for preferential tariff treatment;
(3) A written statement indicating whether or not 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 or not 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.