Registering as self-employed sounds like a big step, but for a side hustle it's a free online form and a date to remember. This guide covers whether you need to, by when, and what happens next. If you sell online, the Vinted tax checker works out your dates for you.
Do you need to register?
Answer three questions:
- Are you trading? Buying things to sell on, making things to sell, or selling a service (like dog walking or tutoring) usually counts. Selling your own old things usually doesn't.
- Was your trading income over £1,000 in a tax year? Count what customers paid you, before costs, across all your side hustles. £1,000 or less is covered by the trading allowance.
- Have you already told HMRC about this income? If not, and you answered yes to both of the above, you usually need to register.
If you already send tax returns for something else, like renting out a flat, you still need to tell HMRC you've started self-employment.
When do I need to register as self-employed?
Register by 5 October after the end of the tax year in which you went over £1,000. The tax year runs from 6 April to 5 April.
| You first went over £1,000 in | Register by | File and pay by |
|---|---|---|
| 6 April 2024 to 5 April 2025 | 5 October 2025 | 31 January 2026 |
| 6 April 2025 to 5 April 2026 | 5 October 2026 | 31 January 2027 |
| 6 April 2026 to 5 April 2027 | 5 October 2027 | 31 January 2028 |
If a date here has passed, register now. If you pay all the tax you owe by the 31 January date, there's usually no penalty for registering late. If the 31 January date has passed too, tell HMRC as soon as you can: penalties are usually lower if you tell HMRC before they contact you.
Sole trader or self-employed: what's the difference?
For tax, there isn't one. A sole trader is simply a self-employed person running a business on their own. You register with HMRC as self-employed. You don't need to register with Companies House, and you can trade under your own name or a business name.
A limited company is different. It's a separate legal person: it registers with Companies House, pays Corporation Tax and files its own accounts. Most side hustles don't need one.
How to register
You register online on GOV.UK. It's free. You'll be asked for personal details, including your National Insurance number, and basic details of your self-employment, such as when you started.
HMRC usually sends your Unique Taxpayer Reference (UTR) by post about 15 days after you register. You can also find it in the HMRC app or your personal tax account. You need it to file your return, so don't leave registering until the last minute.
What if you've missed the deadline?
Tell HMRC as soon as you can. If you register late but still file your return and pay all the tax you owe by 31 January, there's usually no penalty for registering late.
Filing late is different:
- £100 penalty as soon as the return is late, even if you owe no tax
- £10 a day after 3 months, up to £900
- 5% of the tax due or £300, whichever is greater, after 6 months and again after 12 months
Paying late adds interest, and penalties of 5% of the unpaid tax at 30 days, 6 months and 12 months.
If more than one tax year is involved, or you're not sure which years count, it's worth getting advice before you file. If you've had a letter from HMRC, see what to do about an HMRC nudge letter.
After you register
- Keep records of what you sold, what customers paid, and your costs.
- File online by 31 January after the tax year ends.
- Payments on account: if your tax bill is £1,000 or more, HMRC usually also asks for two advance payments towards next year, each half the bill, on 31 January and 31 July. This doesn't apply if more than 80% of your tax is already taken from your pay.
- Making Tax Digital: if your self-employment and property income before expenses is over £30,000 in the 2025 to 2026 tax year, Making Tax Digital usually applies from 6 April 2027. Over £20,000 in 2026 to 2027, it usually applies from 6 April 2028.