How to register as self-employed with HMRC

If you’re earning money working for yourself, at some point you need to tell HMRC. It’s simpler than it sounds, and the whole thing takes about fifteen minutes.

Here’s when, how, and what actually happens afterwards.

Checked against GOV.UK on 20 July 2026. Figures are for the 2026/27 tax year; sources at the end.

When do you need to register?

You need to register for Self Assessment as a sole trader if, in a tax year, you earned more than £1,000 from self-employment. That £1,000 is the trading allowance. Earn under it and you generally don’t need to register or pay tax on it.

You can start trading straight away without registering. The obligation is triggered by the £1,000, not by starting.

The £1,000 is gross income, not profit. This trips up more people than any other part of the process. If you turned over £2,500 and spent £1,900 on stock, your profit was £600, but your income was £2,500, and you’re over the threshold. The trading allowance is measured before expenses.

The deadline

5 October following the end of the tax year in which you started.

The tax year runs 6 April to 5 April. So if you started trading in November 2026, that falls in the 2026/27 tax year, which ends on 5 April 2027, so you register by 5 October 2027 and file your first return by 31 January 2028.

Yes, that’s a long runway. No, don’t use all of it.

How to register

1. Go to GOV.UK and search “register for Self Assessment”.
2. Create a Government Gateway account if you don’t already have one, or sign in to the one you have.
3. Register as self-employed (sole trader). You’ll be asked for your name, address, National Insurance number, the date you started trading, and what your business does.
4. HMRC sends you a UTR (Unique Taxpayer Reference), a 10-digit number. Keep it somewhere permanent. You’ll need it every year, and for a surprising number of other things.
5. An activation code for online filing arrives separately.

That’s it. It’s free, and there’s no approval step. You’re not applying for anything, you’re telling HMRC something.

The bit that catches people out

Registering is not filing, and the UTR doesn’t arrive instantly.

HMRC posts the UTR to you. Then the activation code for online services arrives separately, also by post. You can’t file until you have both.

Every year, people register in mid-January thinking they’ve dealt with it, then miss the 31 January deadline waiting for a letter. That’s an automatic £100 penalty caused entirely by timing.

Register as soon as you know you’ll cross £1,000. There’s no downside to being early and no benefit to being late.

What you’ll need to hand

• Your National Insurance number
• Your address, and the date you started trading
• A short description of what the business does
• If you’ve filed before, your existing UTR

You don’t need a business name, a business bank account, or anything from Companies House. Sole traders don’t register with Companies House at all. That’s limited companies.

What happens next

Once registered, you file a Self Assessment tax return once a year, declaring your income and expenses.

Deadline	What’s due
31 October	Paper return
30 December	File online to have the bill collected via your PAYE code
31 January	Online return and payment
31 July	Second payment on account, if you make them

You pay Income Tax and Class 4 National Insurance on your profit, which is income minus allowable expenses. For 2026/27:

Band	Profit	Income Tax	Class 4 NI
Personal allowance	Up to £12,570	0%	0%
Basic rate	£12,571 to £50,270	20%	6%
Higher rate	£50,271 to £125,140	40%	2%

Class 2 National Insurance won’t produce a bill for most people. At £7,105 of profit or more it’s treated as paid, so your State Pension record builds without you paying anything. Below that you can pay it voluntarily at £3.65 a week to avoid a gap in your record.

Which is exactly why tracking matters from day one. Your bill is based on profit, and profit is only accurate if you recorded what you spent as well as what you earned.

Four things to do in your first week

1. Start a separate savings pot for tax. Move 25 to 30% of every payment into it. In your first year lean towards 30, because payments on account are coming and they turn your first January into roughly 150% of the bill you calculated.

2. Start recording expenses immediately, in the categories your return will ask for: office costs, travel, stock, premises, advertising and so on. Using HMRC’s headings from day one turns filing into transcription.

3. Consider a separate bank account. You don’t legally need one as a sole trader, unlike a limited company. But mixing business and personal transactions makes every future return harder, and makes proving anything much harder if you’re ever asked.

4. Go back and check pre-trading costs. You can generally claim expenses incurred before you started trading, treated as if they happened on your first day. The laptop, the domain, the initial stock, the setup fees. People miss these because they weren’t “in business” yet when they spent the money.

Common mistakes

• Assuming the £1,000 is profit. It’s gross income.
• Registering too late and then missing the filing deadline waiting for a UTR.
• Thinking a loss-making year means no return. If you’re registered, you file. Even a £0 year. The £100 penalty applies whether or not you owe tax.
• Not telling HMRC when you stop. If you cease trading, say so. Otherwise returns keep being expected and penalties keep accruing on returns you didn’t know about.
• Forgetting other income. The return covers everything untaxed, not just the self-employment.

Make the yearly return a non-event

The people who dread January are the ones with a shoebox of receipts. The people who don’t are the ones who tracked as they went.

Sedonis keeps your income, expenses and profit in one private place all year, so filing is reading off numbers rather than reconstructing them. Free to start.

Next steps

• Sole trader vs limited company · if you’re still deciding
• The self assessment guide · what the first return involves
• What you can claim as a sole trader
• Self-employed tax calculator · see the bill before it arrives
• How to start a business in the UK · the full nine-step guide

Checked against GOV.UK on 20 July 2026: set up as a sole trader, Self Assessment deadlines, Income Tax rates, self-employed National Insurance. Rates change, usually each April.

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General information, not tax or legal advice. Always check GOV.UK or an accountant for your circumstances.