All import and export commercial transactions require commodities on Customs declarations to be classified according to an appropriate tariff heading. The tariff classification code is directly linked to the rate of duty payable on that commodity. Classification operates as part of the international Harmonised Commodity and Coding System, under the WCO Harmonised System Convention.

In cases where the tariff classification of goods is complex, i.e. the goods could easily be classified under two tariff headings or if there is no clearly identifiable appropriate tariff heading, it is the duty of the importer to approach the ERS and apply for a written tariff determination. To contact ERS please approach the ERS contact centre, the contact centre information can be found.