If you became self-employed last tax year, one date matters more than most: 5 October. That is the deadline to tell HMRC you need to file a Self Assessment tax return. Miss it, and you risk a penalty on top of your normal tax bill. Here is who must register, how to do it, and what to do if you are already late.
Key takeaways
- You must register by 5 October after the end of the tax year in which you started self-employment.
- Registering gets you a Unique Taxpayer Reference (UTR), which you need to file a return.
- Registering is not the same as filing. The online return is due by 31 January.
- If you have missed the date, register now rather than waiting.
What is the Self Assessment registration deadline?
The registration deadline is 5 October following the end of the tax year in which you first had income that needs a return. UK tax years run from 6 April to 5 April. So if you started trading between 6 April 2025 and 5 April 2026, you need to register by 5 October 2026.
Who needs to register?
Most people who work for themselves need to. That includes sole traders such as Uber, Bolt and delivery drivers, and people with untaxed income such as rental income. There is a trading allowance that can cover very small amounts of self-employed income, so not everyone with tiny earnings needs to register. Check the current allowance and conditions on GOV.UK's Self Assessment registration guidance. If you are unsure, registering is the safe choice.
How to register, step by step
- Go to GOV.UK and choose to register as a sole trader or for Self Assessment.
- Sign in or create a Government Gateway account, and enter your details.
- Wait for HMRC to post you a Unique Taxpayer Reference (UTR).
- Use the activation code that follows to activate your online account.
- Keep your records from day one so filing is simple.
The posting step is why you should not leave this to the last day. It can take around ten working days, and longer from abroad.
Registering versus filing
| Registering | Filing your return | |
|---|---|---|
| What it does | Tells HMRC you need to file and gets you a UTR | Reports your income and expenses for the year |
| Deadline | 5 October after the tax year ends | 31 January online (paper is earlier) |
| One-off or yearly | Once | Every year |
Worked example (illustrative)
"Nadia", an illustrative example, started driving for a delivery platform in November 2025, which falls in the 2025/26 tax year. Her registration deadline is 5 October 2026. She registers in August, receives her UTR in the post, activates her account, and has her records ready. Her first return for 2025/26 is then due online by 31 January 2027, so she has plenty of time. Had she waited until 4 October, the posted UTR might not have arrived before the deadline had passed.
What if you have already missed it?
Do not wait. Register straight away and file as soon as you can. HMRC can charge a penalty if you fail to tell it about taxable income, and how much depends on how late you are and how much tax is unpaid. Because the rules and amounts can change, check the current position on GOV.UK. If you are worried, speaking to an accountant early usually costs less than fixing problems later. Our personal tax service helps people register, catch up and file.
Common mistakes
- Confusing registering with filing. They are two separate steps with two separate deadlines.
- Leaving it to the last week. The UTR arrives by post, so late registration can slip past the deadline through no fault of your own.
- Assuming a platform handles it. Apps such as ride-hailing and delivery platforms do not register you or file for you.
Working out what you can claim as an Uber or private hire driver? See our Uber driver tax return guide.
Frequently Asked Questions
When is the Self Assessment registration deadline?
If you became self-employed in the tax year that ended on 5 April, you must register for Self Assessment by 5 October after that tax year ends. For example, if you started trading in the 2025/26 tax year, register by 5 October 2026.
Do I need to register if I earn less than the trading allowance?
Not always. The trading allowance lets you earn a small amount of self-employed income tax-free, and you may not need to register if your income is below it. Check the current allowance and rules on GOV.UK, and register if you are unsure or want to claim expenses instead.
What happens if I miss the 5 October deadline?
Register as soon as you can. HMRC can charge a penalty for failing to tell it about your income, and the penalty depends on how late you are and how much tax is unpaid. Late registration can also push your first return and payment deadlines close together. Check the current penalty rules on GOV.UK.
Is registering the same as filing my tax return?
No. Registering tells HMRC you need to file a return and gets you a Unique Taxpayer Reference (UTR). Your tax return is a separate step. The online return and payment deadline is 31 January after the end of the tax year.
How long does registration take?
HMRC posts your UTR and an activation code to your address, which can take around ten working days, or longer if you are abroad. This is why you should register well before the deadline rather than on the last day.
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Schedule a consultation →Written by the Berber Accounts & Tax team, 124 City Road, London EC1V 2NX, United Kingdom.
Last reviewed: 20 September 2026.
This article is general information, not personal tax advice. Speak to a qualified accountant about your own circumstances before acting on it.