When you need to register
HMRC's rule: register by 5 October following the end of the tax year in which you started self-employment. The UK tax year runs 6 April to 5 April. So if you start trading in, say, July 2025 (within the 2025/26 tax year), you must register by 5 October 2026.
Don't wait that long. Two reasons:
- You need a UTR (Unique Taxpayer Reference) before you can file Self Assessment, and HMRC takes 10-15 working days to issue one.
- Late registration penalties kick in if HMRC has to chase you. The current "failure to notify" penalty is a percentage of the tax you owe (10%-100% depending on whether HMRC sees it as careless or deliberate).
What you'll need to register
- National Insurance number — find on your payslip, NI letter, or Personal Tax Account.
- Government Gateway account — you'll create one as part of the registration if you don't have one already.
- Date you started trading — be honest; HMRC counts the date you began earning income from self-employment, not the date you registered.
- Business address and contact details.
- A description of your business — keep it simple, e.g. "freelance graphic designer" or "personal trainer".
The registration steps
- Go to gov.uk/register-for-self-assessment.
- Choose "I'm self-employed (sole trader)" if asked which type of registration.
- Sign in to or create a Government Gateway account.
- Complete the online form (it asks for your NI number, start date, and business details).
- Submit. HMRC posts your UTR in 10-15 working days; you'll also get an activation code for the Self Assessment online service.
- Once your UTR arrives, you can file Self Assessment from January each year (the filing deadline is 31 January following the tax year).
What to do once you're registered
- Open a separate bank account for business income and expenses. Not legally required, but it makes everything else easier.
- Start tracking expenses from day one. Keep receipts (digital is fine) for at least 5 years after the relevant 31 January filing date.
- Pick bookkeeping software — FreeAgent, Xero, QuickBooks. From April 2026, MTD ITSA will require digital records and quarterly submissions for many sole traders.
- Set aside ~25-30% of profits in a savings account for your tax bill. The first year stings — you may owe last year's tax plus a payment on account toward this year's.
- Talk to an accountant if your turnover is over £25K or you're unsure about expenses. We can match you with a specialist for free.
Frequently asked questions
How long does it take to register as self-employed?+
The online form takes about 15 minutes. After you submit, HMRC issues your UTR by post in 10-15 working days. The activation code for the Self Assessment online service comes separately.
What happens if I register late?+
If you miss the 5 October deadline, HMRC charges a 'failure to notify' penalty — typically a percentage of the tax owed. Register as soon as you realise; voluntary disclosure usually leads to lower penalties than HMRC catching you.
Do I need to register if I earn under £1,000?+
If your self-employment income is under £1,000 in a tax year, you can usually use the trading allowance and don't need to register or file Self Assessment. Above £1,000, you do need to register.
Can I register as self-employed and have a PAYE job?+
Yes. Many people are employed and self-employed at the same time. You'll declare both incomes on your Self Assessment, and HMRC will calculate the combined tax.
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