Guides › Self Assessment Deadlines 2026-27: Key Dates
Self Assessment Deadlines 2026-27: Key Dates
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Not tax advice. Information only. Check GOV.UK or a qualified adviser for your own situation. Dates and rules were last checked against GOV.UK on 17 October 2026 and can change.
Short answer: For the 2025 to 2026 tax year (6 April 2025 to 5 April 2026), GOV.UK says your online return and the tax you owe are due by 11:59pm on 31 January 2027. A paper return is due by 11:59pm on 31 October 2026.
Calendar
| Date | What | Source wording |
|---|---|---|
| 5 October 2026 | Tell HMRC you need to file (register) if you haven't filed before, or registered before but did not need a return for 2024 to 2025 | "You must tell HMRC by 5 October" |
| 31 October 2026 | Paper return must be received by HMRC | 11:59pm |
| 30 December 2026 | Online return deadline if you want to pay a bill through your tax code | 11:59pm |
| 31 January 2027 | Online return deadline and payment of tax owed (balancing payment and first payment on account) | 11:59pm |
| 31 July 2027 | Second payment on account, if you make payments on account | midnight |
You can submit a return any time on or after 6 April 2026 up to the deadline. If you don't know your profit for the whole year, GOV.UK says you still need to send a return by the deadline (it has a page on how).
Not all dates apply to everyone
- The tax code route has conditions (see pay your bill).
- Payments on account depend on last year's bill (explained here).
- If you register after 5 October 2026 your filing deadline can differ (see).
What if you miss one?
See missed the deadline: penalties.
Calendar file
Use our free deadlines calendar (.ics) generator to add these dates, with reminders, to your calendar. It runs in your browser: nothing is stored or sent.
FAQ
Is the deadline the same for paper and online? No: 31 October 2026 paper, 31 January 2027 online.
What time on 31 January? 11:59pm, per GOV.UK.
Does paying late mean a penalty even if I filed on time? GOV.UK lists penalties for paying late as well as filing late.
What we could not verify
- Weekend or bank-holiday effects on payment arrival (the pay page says to allow time by method).
- Special cases such as trustees, non-resident companies and partnerships with a company partner (GOV.UK lists different dates).
Sources (GOV.UK)
- GOV.UK, Self Assessment tax returns: Deadlines — https://www.gov.uk/self-assessment-tax-returns/deadlines (read 17 October 2026)
- GOV.UK, Pay your Self Assessment tax bill — https://www.gov.uk/pay-self-assessment-tax-bill (read 17 October 2026)
- GOV.UK, Understand your Self Assessment bill: Payments on account — https://www.gov.uk/understand-self-assessment-bill/payments-on-account (read 17 October 2026)
Deadlines calendar → Penalty estimator →
Not tax advice. See the disclosure.