If you started working for yourself between 6 April 2024 and 5 April 2025, you may need to tell HMRC by 5 October 2025. That is next Sunday.
Registering is free and done online. It gives you the reference number you need to file your first tax return.
Who needs to register
You usually need to register for Self Assessment if, in the 2024/25 tax year, you:
were self-employed as a sole trader and earned more than £1,000 before expenses
were a partner in a business partnership
had untaxed income, such as rent, that needs a tax return
You can also choose to register with income of £1,000 or less, for example to pay voluntary Class 2 National Insurance.
If you are not sure, HMRC has an online checker: Check if you need to send a tax return.
Who doesn't need to register again
If you were already registered as self-employed and sent a tax return for 2023/24, you don't need to register again. If you registered in the past but did not send a return for 2023/24, you may need to reactivate your account.
If you already file tax returns for another reason, such as rental income, you still need to tell HMRC you have started self-employment.
How to register
Go to Register for Self Assessment on GOV.UK.
Sign in with your Government Gateway user ID, or create one.
Answer the questions about your business, including the date you started.
HMRC sends you a Unique Taxpayer Reference (UTR). This can take a few weeks, so don't leave it to the last day.
If you can't find a UTR you were sent before, see our guide on how to find your UTR number.
What happens next
31 January 2026: deadline to file your 2024/25 tax return online and pay the tax you owe.
You may also have to make your first payment on account for 2025/26 on the same day. This can make your first January bill bigger than you expect, so set money aside now.
If you miss 5 October
Register as soon as you can. HMRC can charge a penalty for telling them late. The penalty is based on the tax that is unpaid because you registered late. If you pay all your 2024/25 tax by 31 January 2026, there is usually no penalty for registering late. This is separate from the penalties for filing your return late.
Summary
If you started working for yourself in 2024/25 and need to register, do it by 5 October 2025. Then file your return and pay your tax by 31 January 2026, and plan for a possible payment on account at the same time.
If you would like us to register you and handle your first return, book a call or contact us.