Penalties for the 2025/26 tax return
The deadline for filing online and paying the balance of your 2025/26 tax is 31 January 2027. The current Self Assessment penalties still apply to the 2025/26 return — including for people who joined Making Tax Digital for Income Tax on 6 April 2026, whose new points-based penalties only start with the 2026/27 tax year.
| Late filing | Penalty |
|---|---|
| 1 day late (from 1 February 2027) | £100 |
| Over 3 months late (from 1 May 2027) | £10 a day, up to 90 days (max £900) |
| Over 6 months late (from 1 August 2027) | 5% of the tax due or £300, whichever is higher |
| Over 12 months late (from 1 February 2028) | Another 5% or £300, whichever is higher |
| Late payment | Penalty |
|---|---|
| Still unpaid 30 days after the deadline | 5% of the unpaid tax |
| Still unpaid after 6 months | A further 5% |
| Still unpaid after 12 months | A further 5% |
| Interest (from 31 January 2027) | Bank Rate + 4% = 7.75% a year |
Late payment penalties apply to the balancing payment, not to payments on account, but interest is charged on any late payment. The 12-month filing penalty can be up to 100% of the tax if HMRC finds you deliberately withheld information. You can appeal if you had a reasonable excuse.
About the interest rate
HMRC charges late payment interest at the Bank of England Bank Rate plus 4 percentage points (the margin rose from 2.5 to 4 points on 6 April 2025). The rate has been 7.75% since 9 January 2026 (Bank Rate 3.75%). On 5 November 2026 the Bank of England raised Bank Rate to 4%, so HMRC’s rate will rise to 8% from a date HMRC announces (usually a couple of weeks later). For interest on the 31 January 2027 deadline, enter 8% above.
How the calculator works
It assumes you file on the last day of the month you pick, and charges daily penalties from 1 May 2027 to that date (up to 90 days). Interest is simple daily interest on the tax owed for the number of days you are late.
FAQ
What is the penalty for filing my tax return 1 day late?
£100, even if you have no tax to pay or you pay on time.
How much is the penalty if my tax return is 6 months late?
At least £1,300 if filed after 31 July 2027: £100 + £900 of daily penalties + the higher of £300 or 5% of the tax due. On £3,000 of tax that is £1,300 plus any late payment penalties and interest.
What happens if I pay my Self Assessment tax late?
Interest starts on 1 February 2027 at 7.75% a year. If the tax is still unpaid 30 days after the deadline, a 5% penalty is added, with further 5% penalties at 6 and 12 months. On £3,000 paid 45 days late that is £150 + about £28.66 interest.
Do the new Making Tax Digital penalties apply to my 2025/26 return?
No. HMRC says the current penalties still apply to the 2025/26 return due 31 January 2027, even if you joined MTD for Income Tax in April 2026.
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”.