Tariff
A tariff is a tax on imports or exports between sovereign states. It is a form of regulation of foreign trade. It is a policy that taxes foreign products to encourage or protect domestic industry. It helps limit trade deficits. The tariff is historically used to protect infant industries and to allow import substitution industrialization.
Tariff
Customs duty is calculated on the determination of the "assessable value" in case of those items for which the duty is levied "ad valorem". This is often the transaction value unless a customs officer determines assessable value in accordance with the Harmonized System. For certain items like petroleum and alcohol, customs duty is realized at a "specific rate" applied to the volume of the import or export consignments.