19 C.F.R. § 190.21
Section 313(a) of the Act, as amended (19 U.S.C. 1313(a) ), provides for drawback upon the exportation, or destruction under CBP supervision, of articles manufactured or produced in the United States with the use of imported merchandise, provided that those articles have not been used in the United States prior to such exportation or destruction. The amount of drawback allowable will not exceed 99 percent of the amount of duties, taxes, and fees paid with respect to the imported merchandise. However, duties may not be refunded upon the exportation or destruction of flour or by-products produced from imported wheat. Where two or more products result, drawback must be distributed among the products in accordance with their relative values, as defined in § 190.2 , at the time of separation. Merchandise may be identified for drawback purposes under 19 U.S.C. 1313(a) in the manner provided for and prescribed in § 190.14 .
19 C.F.R. §190.21