Check how to register for Self Assessment

Use this tool to find out how to register for Self Assessment.

You must register for Self Assessment by 5 October 2025 if you have to send a tax return and you have not sent one before.

If you register after 5 October 2025, HM Revenue and Customs (HMRC) will send you a letter or email with a different deadline to send your tax return by. This will be 3 months from the date on the letter or email.

This service is also available in Welsh (Cymraeg).

If you’ve registered before

If you’ve registered for Self Assessment before but did not send a tax return last year, you must register again to reactivate your account.

If you’re waiting for a Unique Taxpayer Reference (UTR), you can check when you can expect a reply from HMRC.

Before you start

You should check if you need to send a tax return before registering.