How the daily penalty works
For the 2025/26 return, the timeline is simple:
- 1 February 2027: £100 fixed penalty.
- From 1 May 2027: £10 for every day the return is still not filed, for up to 90 days — so up to £900.
- From 1 August 2027: a further 5% of the tax due or £300, whichever is higher.
The important thing to know: only filing stops the daily penalties. Paying the tax does not. So if you are getting close to May, filing the return should come first.
Example: filed on 31 May 2027, £2,000 tax
The calculator is set for a return filed at the end of May 2027 with £2,000 to pay, paid on 31 May (120 days after the deadline):
- Initial penalty: £100
- Daily penalties: 1 May to 31 May is 31 days × £10 = £310
- Late payment penalty: the tax was still unpaid 30 days after the deadline, so 5% of £2,000 = £100
- Interest: £2,000 × 7.75% × 120 ÷ 365 = £50.96
Total: £560.96 on top of the £2,000 tax. Filing penalties are £410 of that; the rest comes from paying late.
How fast the filing penalties grow
Here is the filing side only (tax paid on time, £2,000 due), depending on when you file:
| Return filed by the end of | Filing penalties (£2,000 tax paid on time) |
|---|---|
| February 2027 | £100 |
| March 2027 | £100 |
| April 2027 | £100 |
| May 2027 | £410 |
| June 2027 | £710 |
| July 2027 | £1,000 |
| August 2027 | £1,300 |
| September 2027 | £1,300 |
Filing in April instead of May would have saved £310 in this example. Filing by 31 July caps the daily penalties at £900; from August, the 6-month penalty is added too.
If you are stuck
- Missing paperwork? You can file using reasonable estimates and correct the return later. Tell HMRC which figures are provisional in the “any other information” box.
- Can’t pay? File anyway, then call HMRC or set up a Time to Pay plan online. A plan stops further late payment penalties while you keep to it.
- Good reason for being late? You can appeal each penalty if you had a reasonable excuse and filed as soon as it ended.
Pay the penalties too
Penalties are bills in their own right. If a penalty is not paid within 30 days of the penalty notice, HMRC charges interest on it as well, at the same 7.75% rate. Once your return is filed, your online account shows everything you owe in one place, so you can clear it in one go or include it in a payment plan.
Assumes the return is filed on the last day of the month you choose. The interest rate is 7.75% (from 9 January 2026) and may change when the Bank of England moves base rate.
FAQ
When do the £10 daily penalties start for the 2025/26 return?
On 1 May 2027, if the return still has not been filed. They run for up to 90 days, so the maximum is £900.
What do I owe if I file on 31 May 2027?
Filing penalties of £410: £100 plus 31 days at £10. If you also pay £2,000 of tax on 31 May, add a £100 late payment penalty and £50.96 interest — £560.96 in total.
Does paying my tax stop the daily penalties?
No. Only filing the return stops them. Paying stops the interest growing, so do both as soon as you can.
Sources (checked 5 November 2026): GOV.UK “Self Assessment tax returns: penalties” (gov.uk/self-assessment-tax-returns/penalties); GOV.UK “Penalties for Making Tax Digital for Income Tax” (current penalties apply to the 2025 to 2026 return due 31 January 2027); GOV.UK “HMRC interest rates for late and early payments” (7.75% from 9 January 2026); Finance Act 2009 Schedules 55 and 56; ICAS “Self-assessment penalties: which regime applies for 2025-26 and 2026-27”.