Before you start
Have these to hand:
- National Insurance number
- Government Gateway login (or create one during the process)
- The exact date you started trading (the date you began earning income, not the date you decided to register)
- A description of your business in one line
- Your home or business address
Step-by-step
- Go to gov.uk/register-for-self-assessment and click "Self-employed (sole trader)".
- Sign in to Government Gateway. Create an account if you don't have one — you'll need an email, then HMRC sends a verification code.
- Confirm your identity (HMRC may ask for ID details, P60, or other info).
- Fill in the registration form: NI number, start date, business name (your own name is fine for sole traders), business description, address.
- Submit.
- HMRC posts your UTR in 10-15 working days.
- Activate the Self Assessment online service when the activation code arrives (separate post).
Common mistakes that cause penalties
- Backdating the start date. If you started trading earlier than you've registered for, HMRC will spot it and the penalty for late notification can be 10-100% of the tax owed.
- Using a partner's NI number by mistake. Common with couples; check carefully.
- Registering as the wrong type. If you're trading via a limited company, you DO NOT register as a sole trader — Companies House handles registration.
- Not telling HMRC if you stop trading. If you cease, file a final return and tell HMRC, or you'll keep getting reminders forever.
FAQ
Frequently asked questions
I forgot to register on time. What now?+
Register as soon as possible. HMRC's penalty for failure to notify is based on the tax owed — voluntary disclosure usually leads to a much smaller penalty than HMRC catching you. An accountant can help you make the disclosure properly.
Do I need to register if I'm only doing a few jobs on the side?+
If your self-employed income exceeds £1,000 in a tax year, yes. Below £1,000 the trading allowance covers you and registration isn't required.
Can my accountant register me?+
Yes — agents can register clients via HMRC's agent portal. Many sole traders prefer this if they're already engaging an accountant.
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