Last updated: 14 October 2026
Will you be charged the £100 penalty for a late tax return?
Yes, if your Self Assessment return is filed after the deadline, even by one day and even if you owe no tax. The online deadline is 31 January after the end of the tax year, so 31 January 2027 for 2025/26. Further penalties follow if the return is 3, 6 and 12 months late. You can appeal if you had a reasonable excuse, and HMRC may cancel the penalty if you shouldn’t have been asked to file at all.
Late filing penalties
| How late | Penalty |
| 1 day | £100 |
| 3 months | £10 a day for up to 90 days (maximum £900) |
| 6 months | £300 or 5% of the tax due, whichever is higher |
| 12 months | Another £300 or 5%, or up to 100% if deliberately withheld |
A return 12 months late could cost £1,600 in penalties even if no tax is owed.
Reasonable excuses
HMRC may accept:
- Serious illness or a hospital stay
- The death of a close relative shortly before the deadline
- HMRC’s online service failing
- Postal delays you couldn’t have predicted
- Fire, flood or theft that prevented filing
Not usually accepted: forgetting, relying on someone else, finding the system difficult, or lack of money.
If you didn’t need to file
If HMRC sent you a notice to file but you didn’t need one, for example because your income is all taxed through PAYE, ask HMRC to withdraw the notice. If it agrees, the penalty is cancelled.
Example
Gemma files her 2025/26 return on 15 February 2027. She gets a £100 penalty. If she had waited until 1 May 2027, she would also have been charged daily penalties of £10 from that date.
How to appeal
- Appeal online or using form SA370 within 30 days of the penalty notice
2. Explain your excuse and when it ended
3. File the return as soon as possible
4. If HMRC refuses, you can ask for a review or appeal to the tribunal
Changes coming
Taxpayers in Making Tax Digital for Income Tax, from April 2026, are moving to a points-based late submission penalty system. Points build up for each late quarterly update or return, with a £200 penalty once the threshold is reached.
Paper returns
The deadline for paper returns is 31 October. Filing on paper after that is late, even if it’s before 31 January, unless you file online instead.
Avoiding penalties next year
Register for Self Assessment by 5 October if you are new to it, gather your P60, bank interest and other records soon after 5 April, and file early. Filing early does not mean paying early: the tax is still due on 31 January, but you will know the amount months in advance and can plan for it.
Frequently asked questions
Is the penalty charged if I owe no tax?
Yes, the £100 is fixed.
Can I pay in instalments?
You can ask HMRC for a payment plan.
Does interest apply to penalties?
Yes, if paid late.
Will HMRC remind me?
Not always; set your own reminder.
Related: late filing fines when no tax is owed, interest and penalties for late payment and a million taxpayers missing the deadline.
Talk to Accotax
Want this handled for you? Our team at Accotax can help with Self Assessment returns. See our small business accountants service, or contact us for a free, no-obligation quote.
This page is general guidance based on HMRC rules for the 2026/27 tax year, checked against gov.uk on 14 October 2026. It is not personal advice, so speak to an accountant about your own situation.
