What is the penalty for filing a Self Assessment tax return late?

Deadlines for the 2025/26 tax return

Paper return: 11:59pm on 31 October 2026. Online return: 11:59pm on 31 January 2027. Pay any tax owed: 11:59pm on 31 January 2027.

If you want HMRC to collect what you owe through your tax code, file online by 30 December 2026.

Late filing penalties

The penalties grow the longer your return is late.

These are added together. HMRC has an online tool to estimate your penalty.

Worked example: 7 months late

Your return is 7 months late and you owed £2,000.

• £100 initial penalty
• £900 in daily penalties (90 days at £10)
• £300 at 6 months (5% of £2,000 is £100, so the £300 minimum applies)

Total: £1,300 in late filing penalties.

Worked example: over 12 months late

Your return is over a year late and you owed £10,000.

• £100 initial penalty
• £900 in daily penalties
• £500 at 6 months (5% of £10,000)
• £500 at 12 months

Total: £2,000 in late filing penalties.

Paying late as well

Paying late is a separate penalty. You pay 5% of the unpaid tax at 30 days, 6 months and 12 months late. HMRC also charges interest on unpaid tax.

How to appeal

You have 30 days from the date the penalty was issued to appeal.

1. Check you have a reasonable excuse (see below).
2. Follow the instructions on your penalty letter and GOV.UK's guide to appealing a Self Assessment penalty. Explain why you were late.
3. Send your return as soon as you can, if you have not already.
4. If HMRC says no, you will be offered a review. You can also go to the tax tribunal.

What may count as a reasonable excuse

• your partner or another close relative died shortly before the deadline
• an unexpected stay in hospital
• a serious or life-threatening illness
• your computer or software failed while you were doing your return
• a fire, flood or theft
• postal delays you could not have expected

These do not count: not getting a reminder from HMRC, finding the online system hard, making a mistake on your return, or a payment failing because you did not have enough money.

If you miss the 30-day appeal deadline

You can still appeal, but you must give a reason why you are late.

Across the UK

These penalty rules are the same in England, Scotland, Wales and Northern Ireland.

Related guides

• What are the Self Assessment deadlines?
• When do I need to register for Self Assessment?
• What are payments on account?
• What is the trading allowance?
• Do I pay tax on a side hustle?

Where this comes from

• Self Assessment tax returns: penalties
• Self Assessment tax returns: deadlines
• Estimate your Self Assessment penalty
• Disagree with a tax decision: appeal a penalty
• Disagree with a tax decision: reasonable excuses