Self Assessment paper tax return deadline: 31 October 2026
HMRC must receive paper Self Assessment tax returns for the 2025 to 2026 tax year by 11:59pm on Saturday 31 October 2026. If you file online, the deadline is 11:59pm on 31 January 2027, which is also when the tax you owe must be paid (GOV.UK).
| Deadline | What |
|---|---|
| 5 October 2026 | Tell HMRC you need to file, if you are new to Self Assessment |
| 31 October 2026, 11:59pm | Paper tax return must reach HMRC |
| 30 December 2026, 11:59pm | Online return, if you want HMRC to collect what you owe through your tax code |
| 31 January 2027, 11:59pm | Online tax return, and payment of the tax you owe |
The tax year covered ran from 6 April 2025 to 5 April 2026. HMRC must receive a paper return by the deadline, so a return still in the post on 31 October is late (GOV.UK).
Missed 31 October? File online instead
The paper deadline does not stop you filing: you can still send the same return online until 31 January 2027 without a late filing penalty, because the online deadline is later. That only works if you have not already sent a paper return after 31 October; a late paper return is still late. If you registered after 5 October 2026, HMRC sends you a letter or email with your own deadline, three months from its date, but the tax is still due by 31 January (GOV.UK).
Late filing and payment penalties
- Up to 3 months late: £100.
- After 3 months: £10 a day, up to £900.
- After 6 months: a further 5% of the tax due or £300, whichever is greater.
- After 12 months: another 5% or £300, whichever is greater.
- Paying late: 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest.
From HMRC's penalty rules (GOV.UK). You can appeal if you have a reasonable excuse.
Quick answers
- When is the paper tax return deadline? 11:59pm on 31 October 2026, for the 2025 to 2026 tax year.
- When is the online deadline? 11:59pm on 31 January 2027.
- When do I have to pay? By 11:59pm on 31 January 2027.
- What is the penalty for filing late? £100 at first, then more the longer it runs.
Sources
- GOV.UK: Self Assessment tax returns: deadlines and penalties, checked 17 October 2026
