Self Assessment Deadline Countdown
Days left to file your tax return & pay HMRC – with a built-in penalty estimator
Last updated: June 2026
Days left for each HMRC deadline
Estimate a late-filing & late-payment penalty
Already missed the 31 January online deadline? Enter the date HMRC actually received (or will receive) your return and the tax you owe to estimate the penalty and interest.
Self Assessment deadline countdown 2026/27
The Self Assessment deadline countdown shows exactly how many days you have left to file your tax return and pay HMRC, with every key date pre-loaded so you don't have to look them up. The headline number counts down to the big one – the online filing and payment deadline of 31 January – and the list below tracks the paper return deadline (31 October), the second payment on account (31 July) and the deadline to register for Self Assessment (5 October). The countdown automatically rolls to the correct tax year, so it stays accurate whether you visit in July or in the January panic.
It is built for the 11.5 million-plus people who file a Self Assessment return each year: the self-employed, landlords, company directors, high earners with the High Income Child Benefit Charge, people with side income, and anyone HMRC has asked to file. If you have already missed a deadline, the built-in penalty estimator works out the likely £100 fixed penalty, daily penalties, percentage charges and 7.75% interest so you know roughly what you owe before you log in to HMRC.
How it works
The countdown reads your device's current date and compares it to each HMRC deadline, always picking the next occurrence so the number is never out of date. The penalty estimator applies the official HMRC rules in order:
- 1 day late: an automatic £100 fixed penalty, even if you owe no tax.
- 3 months late: £10 a day for up to 90 days – a maximum of £900 on top of the £100.
- 6 months late: a further penalty of 5% of the tax due or £300, whichever is greater.
- 12 months late: another 5% of the tax due or £300, whichever is greater.
- Late payment: separate penalties of 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest at 7.75% a year (the HMRC late-payment rate from 9 January 2026).
Worked example
Suppose you owe £4,000 in tax for 2024/25 but file your online return and pay on 30 April 2026 – that is 89 days after the 31 January 2026 deadline. You are over the 1-day point but under the 3-month point, so you get the £100 fixed late-filing penalty only (no daily penalties yet). Because the tax is unpaid for more than 30 days, you also get a late-payment penalty of 5% × £4,000 = £200, plus interest of about £4,000 × 7.75% × 89/365 = £75.59. The estimated total is roughly £375.59. File even a day earlier and the figure changes – which is exactly why watching the countdown matters.
Frequently asked questions
When is the Self Assessment deadline for 2025/26?
For the 2025/26 tax year, the online filing and payment deadline is 11:59pm on 31 January 2027. The paper return deadline is earlier, on 31 October 2026. If you need to register for Self Assessment, tell HMRC by 5 October 2026.
What is the penalty for filing a tax return late?
You get an automatic £100 penalty the moment you miss the deadline, even with no tax to pay. After 3 months it is £10 a day up to £900; after 6 months a further 5% of the tax or £300 (whichever is greater); and the same again after 12 months.
What happens if I pay my tax late?
Separately from filing penalties, HMRC charges a 5% late-payment penalty on tax still unpaid at 30 days, 6 months and 12 months, plus interest at 7.75% a year (the rate from 9 January 2026) running daily until you pay.
Can a late penalty be cancelled?
Yes – HMRC may cancel or reduce penalties if you have a reasonable excuse (such as serious illness or bereavement) and file as soon as you can. You can appeal online or by post. This tool gives an estimate only; always confirm the exact amount in your HMRC online account.
Source: Figures verified against GOV.UK Self Assessment deadlines and GOV.UK Self Assessment penalties, plus the HMRC late-payment interest rate of 7.75% from 9 January 2026.