Skip to content

Guide

How to register for Self Assessment

Register for Self Assessment if you need to send a return and you have not sent one before. The deadline is 5 October after the end of the tax year you first need to file for.

Step by step

  1. 1Check whether you need to send a return. Self-employment or property income over the trading allowance, or other untaxed income, are common reasons
  2. 2Register online for Self Assessment. Do it by 5 October after the tax year. For 2025/26 that date was 5 October 2026
  3. 3HMRC posts your UTR (Unique Taxpayer Reference). You can also see it in your HMRC online account or the HMRC app
  4. 4Activate your account, then file and pay by the deadlines for that tax year

Common questions

When do I register for Self Assessment?

By 5 October after the end of the tax year you first need to file for. For the 2025/26 tax year, that date was 5 October 2026.

Common mistakes

  • Waiting until January to register
  • Registering and then assuming the return has been filed
  • Losing the UTR letter

Related guides

Last checked against GOV.UK: 28 October 2026. Tax year 2026/27.

Not affiliated with HMRC. General information, not professional tax advice. Check GOV.UK or speak to a qualified adviser for your situation.