The registration marks of the Channel Islands and the Isle of Man differ from those in the rest of the United Kingdom.

In Jersey the registration marks all start with the letter J and are suffixed by between one and six numbers. Recently, plates have changed to incorporate the Jersey Coat of Arms on the left hand side and the country code GBJ for Great Britain – Jersey. They are similar to the new style of EU plates, although Jersey is actually outside the European Union. There are some exceptions to the standard registration marks. For example, all hire cars in Jersey have a silver letter H displayed against a red background, to the left hand side of the plate.

Registration marks in Guernsey consist purely of numbers, the lower the number, the higher the value of the vehicle. The plates vary in colour, from black digits on yellow or white plates, to silver digits against a black background. Fire and rescue vehicles do not have assigned registration numbers.

Alderney is a dependency of Guernsey, but the registration marks are different. Plates issued here are alphanumerical and all start with the letters AY suffixed by a combination of numbers. These plates feature a black background with white text.

Sark and Herm have no motor vehicles on their roads, apart from agricultural vehicles and therefore have no vehicle registration system.

The system for registering cars in the Isle of Man has changed many times through the years. Now, Isle of Man registration marks have a prefix letter followed by the letters MN. This letter combination is followed by up to three numbers and suffixed by a trailing letter.