19 C.F.R. § 146.95 – Methods of attribution.

(a) Producibility—(1) General. A subzone operator must attribute the source of each final product. The operator is limited in this regard to feedstocks which were eligible for attribution during the current or prior manufacturing period. Attribution of final products is allowable to the extent that the quantity of such products could have been produced from such feedstocks, using the industry standards of potential production on a practical operating basis, as published in T.D. 66-16. Once attribution is made for a particular product, that attribution is binding. Subsequent attributions of feedstock to product must take prior attributions into account. Each refiner shall keep records showing each attribution.
(2) Industry standards of potential production. The industry standards of potential production on a practical operating basis necessary for the producibility attribution method are contained in tables published in T.D. 66-16. With these tables, a subzone operator may attribute final products consumed in, or removed from, the subzone to feedstocks during the current or a prior manufacturing period.
(3) Attribution to product or feedstock not listed in T.D. 66-16.
1. (i) For purposes of attribution, where a final product or a feedstock is not listed in T.D. 66-16, the operator must submit a proposed attribution schedule, supported by a technical memorandum, to the appropriate port director. The port director shall refer the request to the Director, Office of Regulatory Audit (“ORA”), who will verify the refiner's records and will coordinate with the Director, Office of Laboratories and Scientific Services (“OLSS”). The Director, ORA, shall either approve or deny the request. If the request is approved, the Director, ORA, shall publish a modification of T.D. 66-16. If an operator elects to show attribution on a producibility basis, but fails to keep records on that basis, the operator shall use its actual operating records to determine attribution and any necessary relative value calculation upon the Customs Service demand and subject to verification.
2. (ii) An operator may attribute a final product to a feedstock in excess of the amount allowed under T.D. 66-16, when authorized by Customs, without losing the ability to attribute under T.D. 66-16 for all other feedstock-final product combinations. The operator must use its actual production records for the requested feedstock-final product combination. The operator must agree in writing that it will not, and it will not enable any other person, to file a drawback claim under 19 U.S.C. 1313 inconsistent with those actual production records for that feedstock-final product combination. The operator shall file its request in accordance with paragraph (a)(3) of this section. The Director, ORA, and the Director, OLSS, must determine whether T.D. 66-16 needs to be modified and shall publish in the Customs Bulletin each approval granted under this paragraph and request public comments with each such approval.
(4) Attribution to privileged foreign feedstock; relative value. If a final product is attributed to the separation of a privileged foreign feedstock a relative value must be assigned (see section IV of the appendix to this part).
(b) Refinery operating records. An operator may use the actual refinery operating records to attribute the feedstocks used to the removed or consumed products. Customs shall accept the operator's operating conventions to the extent that the operator demonstrates that it actually uses these conventions in its refinery operations. Whatever conventions are elected by the operator, they must be used consistently in order to be acceptable to Customs. Additionally, Customs may use these records to test the validity of admissions into the subzone, consumption within and removals from the subzone.
Example.If the operator mixes three equal quantities of material in a day tank and treats that product as a three-part mixture in its production unit, Customs will accept the resulting product as composed of the three materials. If, in the alternative, the operator assumes that the three products do not mix and treats the first product as being composed of the first material put into the day tank, the second product as composed of the second material put into the day tank, and the third product as being composed of the third material put into the day tank, Customs will accept that convention also.