Sch 3A para 3
(1) A person who becomes liable to be registered by virtue of paragraph 1(1)(a) above shall notify the Commissioners of the liability before the end of the period of 30 days beginning with the day on which the liability arises. (2) The Commissioners shall register any such person (whether or not he so notifies them) with effect from the beginning of the day on which the liability arises.