There are two types of duty chargeable within the Bailiwick of Guernsey. These are Excise Duty and Import Duty (also referred to as Customs Duty).
All goods arriving in the Island from outside the European Community (EC) are potentially liable to import duty. The rates of duty are set by the EC and are the same across all countries of the EC. The duty is calculated by applying the duty rate (as a percentage) to the value of the goods including the freight charged from the originating country to the first port of call within the European Community.
The rates vary according to the commodity imported. Some rates may be as high as 20% or more while for other goods the rate may be free. UK Customs produce a Tariff that is based on the EC tariff and in Guernsey we use this Tariff to assess all Import Duty charges. Goods are classified by "commodity codes" that are listed in the tariff. Commodity codes for goods can be searched by using the electronic tariff here: https://www.gov.uk/trade-tariff.
E.g. Goods imported from USA. Value of goods + shipping from USA to UK x duty rate (% found in Tariff) = duty to be charged.
The Channel Islands are not within the fiscal territory of the European Union and as such the rules that concern excise duties do not apply. Excise duty is classed as an internal tax and we set our own in accordance with local government requirements. Excise duty is chargeable on tobacco goods, alcoholic goods and some fuels imported into or manufactured in the Bailiwick.
The rates are reviewed annually by the States of Guernsey and set at budget time, which is usually in October. These cover Guernsey and Alderney while Sark have their own rates set by the Chief Pleas.
The current list of the States of Guernsey excise rates is available for download on this page.