If you’ve decided sole trader is the right structure for your business, the next step is straightforward: you need to tell HMRC you’re trading. There’s no company to form and no certificate to wait for — just a registration process that gets you set up to pay tax correctly.
Who needs to register
You need to register as a sole trader if you earned more than £1,000 from self-employment in a tax year. This is the trading allowance threshold — below it, you generally don’t need to register or declare the income, though you can choose to if it helps (for example, to build up National Insurance contributions).
Example: Someone selling handmade crafts at weekend markets who brings in £600 over the year doesn’t need to register. The same person scaling up to £3,000 a year does.
It applies regardless of whether this is your main income or a side activity alongside employment.
When to register
You must register by 5 October following the end of the tax year in which you started trading. The UK tax year runs 6 April to 5 April.
Example: If you started trading in November 2025 (within the 2025/26 tax year), you need to register by 5 October 2026.
Registering earlier than the deadline is generally a good idea — it avoids the deadline creeping up on you, and it means your Self Assessment account is ready to go when it’s time to file.
How to register
Registration is done online through HMRC’s website:
- Go to the “register for Self Assessment” service on GOV.UK
- Choose the option for registering as a sole trader (as opposed to registering a partnership or a limited company)
- You’ll need your National Insurance number, contact details, and information about your business (trading name if you have one, business address, and the date you started trading)
- HMRC will set up a Self Assessment record and post you a Unique Taxpayer Reference (UTR) — this can take up to 10 working days, longer if you’re abroad
- Self Assessment tax returns — filed annually, covering income and expenses for the tax year
- Class 2 and Class 4 National Insurance — calculated based on your profits and paid through Self Assessment
- Record keeping — you’re required to keep records of income and expenses for at least 5 years after the 31 January submission deadline
If you don’t already have a Government Gateway account, you’ll create one as part of this process. Keep the login details safe — you’ll use this account every year to file your return.
What happens after you register
Once registered, a few things are now your responsibility:
Example: A self-employed driving instructor registering mid-year will still only file one Self Assessment return covering the whole tax year, reporting income from the date trading started.
A note on trading names
You don’t have to register a business name with anyone — as a sole trader, you can simply trade under your own name, or choose a trading name without formal registration. If you do use a trading name, there are rules about what you can and can’t include (it can’t imply a limited company status, for instance, or be offensive or misleading), and you’ll need to display your own name alongside it on invoices and official documents.
If you’re already trading as a limited company
If you run a limited company and also have separate self-employed income — freelance work outside the company, for example — that income needs registering and declaring in the same way as any other sole trader activity. The two are treated separately by HMRC: company profits go through Corporation Tax and payroll/dividends, while your personal sole trader income goes through Self Assessment in the usual way.
Penalties for late registration
Missing the 5 October deadline doesn’t automatically trigger a fine — the penalty regime is actually tied to late filing and late payment of tax, not the registration date itself. But registering late often means you’re then rushing to register, gather records, and file a return all at once, closer to the 31 January deadline, which is when the real penalties (starting at £100 for a late return) kick in. Registering promptly gives you breathing room.