How do I cancel a Uk tax self assessment ?

You can cancel a UK tax self assessment by contacting HMRC directly. You can call HMRC on 0300 200 3310 or write to them at HM Revenue and Customs, Self Assessment, PO Box 4000, Nottingham NG2 6AA. You will need to provide your name, address and Unique Taxpayer Reference (UTR) when you contact HMRC.