» For other uses of this word, see tariff (disambiguation). A tariff is a tax on goods upon importation. When a ship arrives in port a customs officer inspects the contents and charges a tax according to the tariff formula. Since the goods can't be landed until the tax is paid, it's the easiest tax to collect, and the cost of collection is small. Traders seeking to evade tariffs are known as smugglers. Tariffs may be of various kinds: An ad valorem tariff is a set percentage of the value of th… (More on Tariff)