How to register as self-employed with HMRC (UK)

Registering as self-employed sounds like the sort of official step that ought to be complicated. It isn't. It's a short online form that tells HMRC you're now earning money for yourself, so you can report it once a year through Self Assessment. Registering doesn't trigger a tax bill on its own, and it doesn't commit you to anything you weren't already doing — it just puts you in the system. It's one of the first steps of going freelance; our complete guide to going freelance covers the rest.

This guide walks through the whole thing: whether you need to register, how to do it, what you get back, and the dates to keep. It's written for sole traders — by far the simplest and most common way to work for yourself. (Setting up a limited company is a different route with its own rules, and a decision most people can leave until later, if at all.)

A quick note first: TrustSolo isn't an accountancy, and nothing here is tax advice. It's a plain-English guide to help you get set up properly. For anything out of the ordinary, an accountant is worth the call.

Check whether you need to register

You have to register for Self Assessment once you earn more than £1,000 from self-employment in a tax year — the tax year running from 6 April to 5 April. That £1,000 is the trading allowance: below it, you generally don't need to tell HMRC at all; above it, you do.

Two useful points of reassurance. You can start trading straight away without registering — you don't need HMRC's permission to begin taking on clients. And you can choose to register earlier than you strictly must, which some people prefer just to have it done. There's no penalty for registering before you've crossed the threshold.

Register for Self Assessment as a sole trader

Registering is done online, through gov.uk. You'll answer some straightforward questions about yourself and your work — who you are, when you started trading, and the kind of work you do — and set up an online account with HMRC that you'll use to file your return later.

It's a one-off task. Once it's done, you're registered for Self Assessment and there's nothing further to do until it's time to file your first return after the tax year ends. Set aside twenty quiet minutes, have your details to hand, and it's off your list.

Get your UTR and keep it safe

Once you've registered, HMRC sends you a Unique Taxpayer Reference — your UTR. It's a 10-digit number that identifies you for tax, and you'll need it every time you file. It usually arrives by post around 15 days after you register (longer if you're overseas), so it's worth registering in good time rather than up against a deadline.

Keep the UTR somewhere safe and memorable — you'll reach for it at every Self Assessment, and hunting for it in January is a small stress you can avoid. That's really the whole of the setup: register once, keep your UTR, and you're ready to file when the time comes.

Know your key dates from the start

Registration comes with a few dates worth pinning up somewhere visible:

• Register by 5 October. You must tell HMRC by 5 October following the tax year in which you became self-employed. So if you started in the 2026–27 tax year, the deadline to register is 5 October 2027 — usually a comfortable window, but not one to forget.
• File and pay by 31 January. Your online Self Assessment return, and the tax owed, are due by 31 January for the tax year that ended the previous 5 April. (If you file on paper instead, the deadline is earlier — 31 October.) If you're repaying a student loan, that comes through the same return — HMRC works it out from your Self Assessment rather than from a payslip, so it lands in the January bill alongside your tax.
• Watch for payments on account. Once your bill passes £1,000, HMRC asks you to pay towards next year's bill in advance, in two instalments on 31 January and 31 July. It catches people out the first time, so it's worth knowing it's coming.

Registering is HMRC's part; keeping tidy records so filing is painless is yours. TrustSolo doesn't register you with HMRC and doesn't file your return — but it does keep clean digital records as you invoice, and a running estimate of your Income Tax and Class 4 National Insurance, so that when a deadline comes around your figures are already in order rather than reconstructed in a hurry. You can see how it works under tax.

Get registered when you cross the threshold, keep your UTR somewhere safe, and start logging income and expenses from day one — and the once-a-year return becomes a formality rather than a scramble. When you'd like that kept for you as you work, you can start free — no card required.