How to register as self-employed in the UK (sole trader)

When you must register as self-employed

You need to register if your gross income from self-employment is more than £1,000 in a tax year, which runs from 6 April to 5 April. That's your income before expenses, not your profit. Below £1,000, the trading allowance means you don't usually need to tell HMRC, unless you have to file a tax return for another reason.

You might choose to register even below £1,000, for example to prove you're self-employed or to pay voluntary Class 2 National Insurance to protect your State Pension record. If you're already registered for Self Assessment for something else, such as rental income, you still need to register as self-employed.

Not sure if what you're doing counts as a business? Selling regularly to make a profit, making things to sell, or being paid for services you provide usually does. Selling your own unwanted things usually doesn't. Our guide to side hustle tax covers the grey areas.

The deadline: 5 October

You must register by 5 October after the end of the tax year in which your income went over £1,000. For example, if you start trading in June 2026, that falls in the 2026 to 2027 tax year, which ends on 5 April 2027. You'd need to register by 5 October 2027, then file your online return and pay any tax by 31 January 2028.

You can register as soon as you start, and there's a good case for doing it early. It gets the admin out of the way and you won't be scrambling for a reference number near the deadline. Registering late, or not at all, can lead to penalties.

What you need to register

Go to the 'Register for Self Assessment' page on GOV.UK and choose the option for self-employed people. Registering as self-employed also registers you for Class 2 National Insurance. Have these ready:

• Your National Insurance number. You can apply for one on GOV.UK if you don't have one.
• An HMRC sign-in. You can use Government Gateway or GOV.UK One Login to get into your personal tax account. If you don't have either, you can set one up as you go, and you'll be asked to prove your identity.
• Basic details about the business, such as what it does and when you started.

Getting your UTR and how long it takes

Once you've registered, HMRC gives you a Unique Taxpayer Reference, or UTR. It's a 10 digit number you'll use on every tax return and whenever you deal with HMRC about Self Assessment. Keep it somewhere safe.

HMRC improved its online registration in September 2026. If you register online through your personal tax account, it says you should get your UTR within 72 hours. If it comes by post instead, it can take up to 15 days, and longer if you're abroad. Once it's been issued you can also find it in the HMRC app or your personal tax account.

If your UTR hasn't turned up and the deadline is close, contact HMRC rather than waiting. This is another reason not to leave registering until early October.

What happens after you register

Not much happens straight away. Your first tax return covers the tax year you started in. On it you report your income and allowable expenses, and HMRC works out your Income Tax and Class 4 National Insurance. If you have a job as well, your salary uses up your Personal Allowance first, so more of your profit is taxed. The side hustle tax calculator gives a rough figure to put aside each month.

Class 2 National Insurance isn't something you have to pay any more. If your profits are £7,105 or more, you're treated as having paid it, which counts towards your State Pension. Below that, you can choose to pay it voluntarily at £3.65 a week.

If your gross income is over £1,000 but your expenses are small, you can deduct the £1,000 trading allowance instead of your actual expenses. You can't do both, so use whichever is bigger.

Keep records from day one

Keep a record of every sale and every business expense, backed up by receipts, invoices and bank statements. Most sole traders now use the cash basis, which means you record money when it actually comes in or goes out. You must keep records for at least 5 years after the 31 January deadline for that tax year. A separate bank account isn't required, but it makes this much easier.

Making Tax Digital for Income Tax is being phased in. If your qualifying income is over £50,000 you'll already need compatible software and quarterly updates, with the threshold falling to £30,000 from April 2027 and £20,000 from April 2028. Our guide to Making Tax Digital for sole traders explains what that involves.

If records are the job you always put off, give them a fixed slot each week. Exitnine's weekly check-ins can help make that a habit.

Your first tax bill and payments on account

This is the part that surprises people. If your Self Assessment bill is more than £1,000, and less than 80% of your tax was already taken at source (through PAYE, for example), HMRC also asks for payments on account. These are advance payments towards next year's bill. Each one is half of this year's bill, and they're due on 31 January and 31 July.

In your first year, that makes the January bill bigger than you expect. Say your first tax bill is £2,400. By 31 January you pay that £2,400 plus a first payment on account of £1,200, so £3,600 in total. Another £1,200 is then due by 31 July. If your profits fall the following year, you can ask HMRC to reduce your payments on account.

The simple fix is to move a set percentage of every payment you receive into a separate savings account, so the money is there when the bill arrives. If paying in one go would be a struggle, speak to HMRC early about spreading it.