# Registering for Self Assessment as a sole trader

Canonical: https://taxmo.co.uk/self-assessment-guide/registering
Tax year: 2026/27
Part of: [Self Assessment topics](https://taxmo.co.uk/self-assessment-guide)

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

- [GOV.UK, Register for Self Assessment](https://www.gov.uk/register-for-self-assessment)
- [GOV.UK, Register for Self Assessment if you're self-employed or a sole trader](https://www.gov.uk/register-for-self-assessment/self-employed)
- [GOV.UK, Become a sole trader: register as a sole trader](https://www.gov.uk/become-sole-trader/register-sole-trader)

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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.