You should register with HM Revenue & Customs (HMRC) if you need to complete a Self Assessment tax return.
Information you'll need before you register
You will need:
- Your National Insurance number. In most cases you'll already have this, but if you haven't worked in the United Kingdom before you'll need to get one.
- Your contact details (and the contact details of your business if you've started self-employment).
- Your ten-digit Unique Taxpayer Reference number, but only if you have previously completed a Self Assessment return. You'll find this on letters or forms sent by HMRC about your tax return.
- The date your circumstances changed.
Please see the link below for more details: