When is the Self Assessment deadline?
For the 2025/26 tax year, you must submit your online Self Assessment tax return and pay what you owe by 11:59pm on 31 January 2027. A paper return must reach HMRC by 11:59pm on 31 October 2026. If you are new to Self Assessment, you must tell HMRC by 5 October 2026.
Figures checked against gov.uk on . General information, not tax advice.
At a glance
- Tell HMRC you need a return (new filers)
- 5 October 2026
- Paper return reaches HMRC
- 11:59pm, 31 October 2026
- Online return, if you want to pay through your tax code
- 11:59pm, 30 December 2026
- Online return and Self Assessment payment
- 11:59pm, 31 January 2027
- Second payment on account, if you make them
- 31 July 2027
Which tax year these dates cover
The dates above belong to the 2025/26 tax year, which ran from 6 April 2025 to 5 April 2026. gov.uk says paper and online returns for that year could be sent from 6 April 2026, so there is no reason to wait for the autumn.
Each tax year has its own calendar, so do not assume this year's dates carry over unchanged to the next return.
Filing and paying are two separate deadlines
Both the online return and the payment are due by the same moment on 31 January, but HMRC treats them separately. A return that is a day late costs a fixed penalty even when you owe nothing, and tax paid late attracts its own penalties and interest.
If you have never filed before and register after 5 October 2026, gov.uk says HMRC sends a letter or email with a new deadline, three months from the date on that letter or email, and that you could get a penalty.
More about self assessment deadline
Is the deadline the same for paper and online returns?
No. A paper return must reach HMRC by 31 October 2026, three months before the 31 January 2027 online deadline.