The T1 Transit Form is a customs document used within the European Union that allows non-Union goods to be transported under customs supervision from one location to another without the immediate payment of import duties and taxes. It is part of the external transit procedure and enables goods to move, for example, from a port to an inland customs office without being cleared for free circulation. The T1 document ensures that goods remain under customs control during transport and are only processed by customs authorities at their final destination.