19 CFR § 4.12 - Explanation of manifest discrepancy.
(a)
(1) Vessel masters or agents shall notify the port director on Customs Form 5931 of shortages (merchandise manifested, but not found) or overages (merchandise found, but not manifested) of merchandise.
(2) Shortages shall be reported to the port direct by the master or agent of the vessel by endorsement on the importer's claim for shortage on Customs Form 5931 as provided for in § 158.3 of this chapter, or within 60 days after the date of entry of the vessel, whichever is later. Satisfactory evidence to support the claim of nonimportation or of proper disposition or other corrective action (see § 4.34) shall be obtained by the master or agent and shall be retained in the carrier's file for one year.
(3) Overages shall be reported to the port director within 60 days after the date of entry of the vessel by completion of a post entry or suitable explanation of corrective action (see § 4.34) on the Customs Form 5931.
(4) The port director shall immediately advise the master or agent of those discrepancies which are not reported by the master or agent. Notification may be in any appropriate manner, including the furnishing of a copy of Customs Form 5931 to the master or agent. The master or agent shall satisfactorily resolve the matter within 30 days after the date of such notification, or within 60 days after entry of the vessel, whichever is later.
(5) Unless the required notification and explanation is made timely and the port director is satisfied that the discrepancies resulted from clerical error or other mistake and that there has been no loss of revenue (and in the case of a discrepancy not initially reported by the master or agent that there was a valid reason for failing to so report), applicable penalties under section 584, Tariff Act of 1930, as amended (19 U.S.C. 1584), shall be assessed (see § 162.31 of this chapter). For purposes of this section, the term “clerical error” is defined as a non-negligent, inadvertent, or typographical mistake in the preparation, assembly, or submission (electronically or otherwise) of the manifest. However, repeated similar manifest discrepancies by the same parties may be deemed the result of negligence and not clerical error or other mistake. For the purpose of assessing applicable penalties, the value of the merchandise shall be determined as prescribed in § 162.43 of this chapter. The fact that the master or owner had no knowledge of a discrepancy shall not relieve him from the penalty.
(b) Except as provided in paragraph (c) of this section, a correction in the manifest shall not be required in the case of bulk merchandise if the port director is satisfied that the difference between the manifested quantity and the quantity unladen, whether the difference constitutes an overage or a shortage, is an ordinary and usual difference properly attributable to absorption of moisture, temperature, faulty weighing at the port of lading, or other similar reason. A correction in the manifest shall not be required because of discrepancies between marks or numbers on packages of merchandise and the marks or numbers for the same packages as shown on the manifest of the importing vessel when the quantity and description of the merchandise in such packages are correctly given.
(c) Manifest discrepancies (shortages and overages) of petroleum and petroleum products imported in bulk shall be reported on Customs Form 5931, if the discrepancy exceeds one percent.