How to register as a sole trader

Register with HMRC for Self Assessment by 5 October following the end of the tax year in which you started trading. You will need your National Insurance number and business details; HMRC then posts you a Unique Taxpayer Reference, without which you cannot file. Registration is free.

The registration itself takes about ten minutes. What catches people is the deadline — it falls up to eighteen months after you started, which is long enough to forget entirely — and the fact that the number you need to file arrives by post.

Working out your deadline

The rule is 5 October following the end of the tax year you started in, and tax years run 6 April to 5 April. So:

Started trading in June 2026 → tax year ends 5 April 2027 → register by 5 October 2027.
Started in March 2027 → the same tax year ends weeks later → register by 5 October 2027 as well.

Which is the trap: start in March and you have seven months, start in April and you have eighteen. The long version feels like no deadline at all until it has passed.

What HMRC asks for

Your details — name, date of birth, address, National Insurance number.
The business — what you do, the trading name if you use one, and the date you started.
Contact details, and a Government Gateway account if you do not already have one.
Wait for the UTR to arrive by post. Nothing can be filed before it does.
Activate the online account with the code that follows, and keep both somewhere you will find them in January.

"The date you started" means when you began trading, not when you registered. If that was two years ago, say so — the honest date produces a cheaper outcome than a convenient one, and HMRC can usually see the difference.

Do you need to at all?

Below the £1,000 trading allowance, with nothing else requiring a return, you may not. The allowance applies to income, not profit: £3,000 of sales with £2,500 of costs is £3,000 of income and over the line, even though the profit is £500.

Other things pull you into Self Assessment regardless of self-employment — property income, foreign income, high income with Child Benefit, a capital gain. Our filing check runs through the triggers in half a minute.

Not sure whether you are late, or by how much?

Tell us when you actually started and we will tell you where you stand, what needs filing, and what it is likely to cost — including cases where nothing is owed and the fix is simply registering.

Ask on WhatsApp Or send an email

Free assessment first. If there is work to do, you get a fixed quote in writing before anything starts.

After you register

You are in Self Assessment: a return each year covering 6 April to 5 April, filed online by31 January, with the tax due the same day. Miss it and it is £100 immediately,charged even when you owe no tax.

The one habit worth forming from day one is separating business money from personal money and keeping the receipts. Everything else — the deadlines, thepayment mechanics, the expenses — is learnable in an afternoon or delegated to us. Reconstructing a year of mixed transactions from bank statements is neither.

Questions people ask

When do I have to register by?

5 October following the end of the tax year you started trading in. Start in June 2026 and that tax year ends 5 April 2027, so the deadline is 5 October 2027 — a year and a bit away, which is exactly why people forget it.

Do I need to register if I earn very little?

Not if your self-employed income for the year is under the £1,000 trading allowance and you have no other reason to file. Above it, yes — and note the allowance applies to income, not profit, so a £3,000 turnover with £2,500 of costs is over the line.

What is a UTR and how long does it take?

Your Unique Taxpayer Reference — a ten-digit number identifying you to HMRC for Self Assessment. It arrives by post after you register, and you cannot file without it. This is the step that turns a forgotten registration into a missed deadline: registering the week before 31 January does not work.

Sole trader or limited company?

Register as a sole trader first if you are starting out and unsure. It is quicker, cheaper and reversible — you can incorporate later. Going the other way, closing a company you did not need, is more work than never having formed it.

What if I have been trading for years without registering?

It is fixable and it is common. Register, file the outstanding returns, and pay what is due. Penalties are based partly on whether you came forward or HMRC found you, so doing it now is materially cheaper than doing it after a letter arrives.

Do I need a business bank account?

Not legally, as a sole trader — you and the business are the same person for tax. In practice a separate account makes the year end far quicker and much cheaper to prepare, because nobody has to separate your shopping from your supplies.

Figures are for the tax year shown and change every April. They are general information, not advice — we check the current position for your circumstances before anything is filed.

Reviewed 19 October 2026.

Part of our work on self-employment and self assessment — if you want someone to take it off your hands, start with our Self Assessment accountant page.