Self Assessment Registration Deadline, 5th October 2026, Don't Miss It
As of 28 September 2026, the deadline to register for Self Assessment for 2025/26 is one week away: Monday 5th October. If you became self-employed, a landlord, or received untaxed income, check whether you need to tell HMRC. Registration is separate from filing your return, so do not leave it until January.
Who needs to register for Self Assessment?
Register if, during 2025/26 (6th April 2025 to 5th April 2026), you:
- Started as a sole trader and your gross trading income was more than £1,000.
- Became a landlord or received rental income that needs to be reported.
- Had more than £2,500 in untaxed income, for example from casual work or other sources.
- Had income over £100,000, or need to declare a capital gain.
Allowances and your circumstances can affect what must be reported, so check HMRC guidance if unsure. Learn about our sole trader accounts, landlord property accounts and landlord property accounts and Personal Tax Returns.
How do you register?
Use HMRC's official online service at gov.uk/register-for-self-assessment. Choose the option that matches your circumstances, enter accurate details and keep a record of your application. Avoid sites charging simply to submit it.
What if you miss 5th October?
Missing 5th October does not usually mean an immediate separate late-registration penalty, but register as soon as possible to obtain your UTR and prepare your return. Do not ignore the requirement.
If you owe tax and miss the online filing deadline of 31st January 2027, the initial late-filing penalty is £100. Further penalties may follow if the return remains outstanding; late payment can also mean interest and penalties. Keep income and expense records and plan ahead. Our self-employed services can help with record-keeping and reporting.
Self Assessment registration, your questions answered
1. Is 5th October 2026 the deadline to submit my tax return?
No. It is the date to notify HMRC that you need to file. Paper returns are due 31st October 2026, online returns and payment by 31st January 2027.
2. I have a PAYE job and a side hustle. Do I need to register?
Possibly. Gross trading income above £1,000 in 2025/26 may mean you need to register, even if your job is taxed through PAYE. Check HMRC guidance for your circumstances.
3. How long does it take to get a UTR?
It can take up to 10 working days to arrive by post. Apply promptly and check your address, as you need the UTR to file.
4. Have I already missed the deadline if I did not register by 5th October?
No. Register as soon as possible. There is not usually an immediate standalone penalty, but delay leaves less time to get your UTR and file.
5. What is the penalty if I file late?
The initial late-filing penalty is £100. Further penalties can apply while the return remains overdue, and late payment can mean interest and additional charges.
6. Can I send a paper return after 31st October?
Paper returns are due 31st October 2026. Online filing is available until 31st January 2027. Register early to receive your UTR and arrange access.
Need help with your Self Assessment?
We support sole traders, landlords and individuals with their tax returns and bookkeeping. Get in touch with our Guildford team to discuss what you need.