When two or more provisions seem to cover the same merchandise, the prevailing provision is determined in accordance with the legal notes and the General Rules of Interpretation for the tariff schedule. Liquidation Customs officers at the port of entry or other officials acting on behalf of the district director review the classifications and valuations, as well as other required import information, for correctness or as a proper basis for appraisement, as well as for agreement of the submitted data with the merchandise actually imported. The entry summary and documentation may be accepted as submitted without any changes. In this situation, the entry is liquidated as entered. Liquidation is the point at which the Customs Service's ascertainment of the rate of duty and amount of duty becomes final for most purposes.
Liquidation is accomplished by posting a notice on a public bulletin board at the custom house.
The Customs Service may determine that an entry cannot be liquidated as entered for one reason or another. For example, the tariff classification may not be correct or may not be acceptable because it is not consistent with an established and uniform classification practice. If the change required by this determination results in a rate of duty more favorable to an importer, the entry is liquidated accordingly and a refund of the applicable amount of the deposited estimated duties is authorized. On the other hand, a change may be necessary which imposes a higher rate of duty. For example, a claim for an exemption from duty under a free-rate provision or under a conditional exemption may be found to be insufficient for lack of the required supporting documentation.