Quotas are established by legislation, by directives and by proclamations issued under the authority contained in specific legislation. The majority of import quotas are administered by the U.S. Customs Service. The Commissioner of Customs controls the importation of quota merchandise but has no authority to change or modify any quota. Tariff-rate quotas provide for the entry of a specified quantity of the quota product at a reduced rate of duty during a given period. There is no limitation on the amount of the product which may be entered during the quota period, but quantities entered in excess of the quota for the period are subject to higher duty rates.
Some absolute quotas are global, while others are allocated to specified foreign countries.
Imports in excess of a specified quota may be exported or warehoused for entry in a subsequent quota period. The usual customs procedures generally applicable to other imports apply with respect to commodities subject to quota limitations. The quota status of a commodity subject to a tariff-rate quota cannot be determined in advance of its entry. The quota rates of duty are ordinarily assessed on such commodities entered from the beginning of the quota period until such time in the period as it is determined that imports are nearing the quota level. District directors of Customs are then instructed to require the deposit of estimated duties at the over-quota duty rate and to report the time of official presentation of each entry.