How to register for Self Assessment as a new sole trader

Checked against GOV.UK on 23 October 2026. General information for sole traders in England, Wales and Northern Ireland, not tax advice. Scottish Income Tax rates are different.

Do you need to register?

GOV.UK says you must send a return if, in the last tax year, you were self-employed as a sole trader and earned more than £1,000 before expenses (among other reasons). For a self-employed CIS subcontractor, that almost always means you.

When

By 5 October after the tax year in which you started. If you started between 6 April 2025 and 5 April 2026, that was 5 October 2026. If you start now, it's 5 October 2027, but there's no need to wait.

If you missed 5 October 2026

Register now. HMRC gives you 3 months from its letter to file, but the tax is still due by 31 January 2027. If tax is still unpaid then, you may get a penalty for not telling HMRC in time.

How to register

1. Use GOV.UK's register for Self Assessment service with a Government Gateway account and your National Insurance number.
2. Have your details, start date and type of work ready.
3. Wait for your UTR, which GOV.UK says usually arrives within 15 days. See finding your UTR.
4. In construction, register for CIS too, so contractors take 20% instead of 30%. See registering as a CIS subcontractor.

After registering

• Keep records from day one: see the records checklist.
• Set money aside for tax: the self-employed tax calculator shows how much.
• Send proper invoices: see what a sole trader's invoice must include.
• Know what's coming: see your first tax bill.

This guide is part of our Self Assessment guides for the self-employed.