Check how to register for Self Assessment

You must tell HM Revenue and Customs (HMRC) by 5 October 2025 if you need to complete a tax return for the previous tax year and you have not sent one before.

The previous tax year started on 6 April 2024 and ended on 5 April 2025.

You can tell HMRC by registering for Self Assessment.

If you tell HMRC after 5 October 2025, you could get a penalty.

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.