look the dvla up in the phone book,give them a ring,they are very helpful.they will tell you,if you ask what doc's you need if any.you should be able to go into your nearest dvla office,tell them you want to change the taxation class,there is a form you should be able to pick up from the post office,has to be a p/o that issues tax discs.butI think I filled one in while I was at dvla.