19 C.F.R. § 181.31
Notwithstanding any other available remedy, including the right to amend an entry so long as liquidation of the entry has not become final, where a good would have qualified as an originating good when it was imported into the United States but no claim for preferential tariff treatment on that originating good was made at that time under § 181.21(a) of this part, the importer of that good may file a claim for a refund of any excess duties at any time within one year after the date of importation of the good in accordance with the procedures set forth in § 181.32 of this part. Subject to the provisions of § 181.23 of this part, Customs may refund any excess duties by liquidation or reliquidation of the entry covering the good in accordance with § 181.33(c) of this part.
19 C.F.R. §181.31