If you drive in foreign countries, especially large goods vehicles, you need to be aware that customs officers in other countries may charge extra fuel duty on entry.
Taxes on UK fuel entering other countries
Motor fuel is generally sold at a tax-inclusive price, and British vehicles are not exempt from this form of taxation when abroad. Fuel entering a country in the standard tanks of a vehicle is usually exempt from additional taxes, but some countries restrict the amount of fuel that may be imported duty free.
Under European Union (EU) rules there is no limit on the amount of fuel which may be carried between member states in standard running tanks, provided that it remains in these and is not off loaded.
Although an EU directive now defines what constitutes 'standard tanks', the definition is open to differing interpretation, particularly in France and Belgium. These countries sometimes claim that supplementary tanks fall outside this category. For a tank to qualify as a 'standard tank', a driver must be able to show that it is of a type that was permanently fitted by the manufacturer to all motor vehicles of the same type as the vehicle in question and whose permanent fitting enables fuel to be used directly for propulsion or, where appropriate, by refrigeration or other systems.
French and Belgian authorities sometimes claim that 'catwalk tanks' and 'belly tanks' fail this qualification. Drivers of vehicles are sometimes charged additional duty, or even fined, when carrying fuel in such tanks.