In drawing up the national tariff, the revenue departments often specifies the rate of customs duty with reference to the HS code of the product.
In some countries and customs unions, 6-digit HS codes are locally extended to 8 digits or 10 digits for further tariff discrimination: for example the European Union uses its 8-digit CN (Combined Nomenclature) and 10-digit TARIC codes.
A duty levied on goods being imported is referred to as an import duty.
Similarly, a duty levied on exports is called an export duty.
A Customs authority in each country is responsible for collecting taxes on the import into or export of goods out of the country.