Missing the 31 January self assessment deadline is expensive, and the cost builds the longer it is left. These are the penalties for the 2025/26 return, due by 31 January 2027.
Late filing
- On the day after the deadline: a fixed £100 penalty, even if you owe no tax.
- After three months: £10 a day for up to 90 days, so up to £900.
- After six months: a further 5% of the tax due or £300, whichever is higher.
- After twelve months: another 5% or £300, and more if HMRC thinks information was withheld deliberately.
Late payment
Interest runs from the day after the payment was due. On top of that, a penalty of 5% of the unpaid tax applies at 30 days, again at six months and again at twelve months.
What to do if you are going to be late
File as soon as you can. The daily penalties do not start until May, so a return filed a few weeks late costs £100, not more. If you cannot pay in full, contact HMRC before the deadline about a Time to Pay arrangement. Our post on Time to Pay explains how it works.
Reasonable excuse
HMRC will cancel a penalty if you had a reasonable excuse, such as serious illness or a bereavement close to the deadline. Being busy, forgetting or relying on someone else does not usually count. You must file as soon as the excuse ends.
Making Tax Digital is different
From 2026/27, people in Making Tax Digital move to a points-based system for late submissions and new rules for late payment. The 2025/26 return is still under the rules above. See our Making Tax Digital page for more.
If you are running late or already have penalties, talk to us. We deal with HMRC directly once you authorise us as your agent. See our personal tax page or call 01242 226789.
