Registering for Self Assessment as a sole trader

Tax year 2026/27

You register for Self Assessment when you first need to send a tax return. As a sole trader you register through GOV.UK's Self Assessment registration service.

Who must register

GOV.UK says you must register as a sole trader if any of these apply:

  • You earned more than the trading allowance from self-employment in a tax year (6 April to 5 April)
  • You need to prove you are self-employed, for example to claim Tax-Free Childcare
  • You want to make voluntary Class 2 National Insurance payments to help you qualify for benefits and the State Pension

The deadline

You must tell HMRC by 5 October after the end of the tax year you need to file for. For the 2026/27 tax year that is 5 October 2027. Registering after the deadline can lead to a penalty.

After you register

HMRC identifies your Self Assessment by your Unique Taxpayer Reference (UTR). GOV.UK has a page to check when you can expect a reply from HMRC while you wait for it.

Common mistakes

  • Waiting for the first January deadline to register. Registration is due by 5 October.
  • Assuming a side income does not count. Measure it against the trading allowance.

Sources

Checked against GOV.UK on 6 November 2026. Rules and figures change, so verify on GOV.UK before you rely on this. General information, not tax advice.