TaxYearSheetsLate filing and late payment penalties (current rules)
| How late | Late tax return | Late payment |
|---|---|---|
| 1 day | £100 | Interest starts |
| 30 days | – | 5% of tax unpaid |
| 3 months | £10 a day for up to 90 days (max £900) | – |
| 6 months | 5% of tax due or £300, whichever is greater | Another 5% of tax unpaid |
| 12 months | Another 5% or £300, whichever is greater (more if information is deliberately withheld) | Another 5% of tax unpaid |
Sources: GOV.UK – Self Assessment penalties; exact timings from Finance Act 2009 Schedule 55 (filing) and Schedule 56 (payment). Late payment interest: HMRC interest rates – 7.75% from 9 January 2026 (base rate plus 4%).
2025/26 return: when each penalty starts
| Date | What happens if still not done |
|---|---|
| 31 January 2027 | Deadline to file online and pay. From 1 February: £100 late filing penalty, and interest on unpaid tax. |
| 2 March 2027 | Last day to pay before the first 5% late payment penalty. |
| 1 May 2027 | £10 daily late filing penalties can start (up to 90 days). |
| 31 July 2027 | Last day to file before the 6-month penalty (5% or £300). |
| 2 August 2027 | Last day to pay before the second 5% penalty. |
| 31 January 2028 | Last day to file before the 12-month penalty. |
| 2 February 2028 | Last day to pay before the third 5% penalty. |
Worked out from the dates in Schedule 55 and Schedule 56, and matched against GOV.UK's own penalty estimator for 2024/25 returns.
If you use Making Tax Digital
From the tax year you join MTD for Income Tax, new penalties replace the ones above. Late submissions get penalty points; at 4 points there is a £200 penalty, and £200 for each further late submission. For 2026/27 payments, late payment penalties are 3% of the tax owed at day 15 and another 3% at day 30, then 10% a year from day 31 (4% and 4% for 2027/28). In your first year you get 30 days before a penalty. There are no penalty points for late 2026/27 quarterly updates. GOV.UK says the new penalties apply to everyone who sends a personal Self Assessment return from April 2027.
Source: GOV.UK – Penalties for Making Tax Digital for Income Tax. Check when MTD starts for you with our MTD checker.
Questions
What is the penalty for a late Self Assessment tax return?
GOV.UK: £100 straight away, then after 3 months £10 a day for up to 90 days (up to £900), then after 6 months 5% of the tax due or £300, whichever is greater, and after 12 months another 5% or £300. The penalties apply even if you owe no tax.
What is the penalty for paying Self Assessment tax late?
GOV.UK: 5% of the tax still unpaid at 30 days, another 5% at 6 months and another 5% at 12 months, plus interest on the amount owed for every day it is late.
What interest rate does HMRC charge on late tax?
The late payment interest rate is the Bank of England base rate plus 4% (since 6 April 2025). HMRC's published rate has been 7.75% since 9 January 2026. It changes when the base rate changes.
Do the rules change with Making Tax Digital?
Yes. If you use Making Tax Digital for Income Tax, a points-based late submission system and new late payment penalties replace these from the tax year you join. GOV.UK says the new penalties apply to everyone who sends a personal Self Assessment return from April 2027. This calculator only covers the current rules.
Can I appeal a Self Assessment penalty?
Yes, if you have a reasonable excuse – the penalty letter explains how. If you can't pay, contact HMRC about a payment plan as soon as possible.