Key takeaways

  • The online deadline for a 2025 to 2026 tax return is 11:59pm on 31 January 2027, and a return filed even one day late gets an automatic £100 penalty.
  • If the return is still not filed after 3 months, HMRC can charge £10 a day from 1 May 2027 for up to 90 days, a maximum of £900.
  • At 6 months late (from 1 August 2027) and again at 12 months late (from 1 February 2028), HMRC adds 5% of the tax due or £300, whichever is greater.
  • Tax still unpaid at the end of 2 March 2027 gets a 5% late payment penalty, with further 5% charges in August 2027 and February 2028.
  • A return can cost £1,600 in late filing penalties after 12 months even if there is no tax to pay.
  • The new points-based penalties apply to Self Assessment taxpayers outside Making Tax Digital from 6 April 2027, so 2025 to 2026 returns stay under the current rules.
  • If you have a reasonable excuse, you can appeal online or on form SA370, and you should file the return as soon as the excuse ends.

If you miss the 31 January 2027 deadline for your 2025 to 2026 tax return, HMRC charges a £100 penalty straight away. Daily penalties of £10 start on 1 May 2027, and further penalties of 5% of the tax due or £300 follow at 6 and 12 months. Late payment penalties and interest are charged separately, so paying late as well as filing late costs more.

When is the 2025 to 2026 tax return due?

The online return is due by 11:59pm on 31 January 2027. GOV.UK’s deadlines page says paper returns were due by 31 October 2026, and the tax you owe must also be paid by 31 January 2027.

If you missed the paper deadline, you can still file online by 31 January 2027 without a penalty. If you registered after 5 October 2026, HMRC gives you 3 months from the date of its letter or email to file, but the payment date stays at 31 January. See our Self Assessment deadlines guide for every date in the year.

What are the late filing penalties?

HMRC charges four layers of late filing penalty, set out in Schedule 55 to the Finance Act 2009. Each layer is triggered by how long the return stays unfiled after 31 January 2027.

Return still not filedFromPenalty
1 day late1 February 2027£100 fixed
3 months late1 May 2027£10 a day, up to £900
6 months late1 August 20275% of tax due or £300
12 months late1 February 20285% of tax due or £300

The £100 applies even if you owe no tax or have already paid. The daily penalty runs for up to 90 days, so it stops building at £900.

At 12 months, the penalty can be much higher if HMRC decides you deliberately withheld information. Schedule 55 sets it at up to 100% of the tax due where the withholding was deliberate and concealed.

How much could a late return cost in total?

A return filed more than 12 months late with no tax due costs £1,600 in late filing penalties. That is £100, plus £900 in daily penalties, plus two minimum penalties of £300.

Where tax is due, the two percentage penalties are 5% of the tax or £300, whichever is higher. On a £10,000 bill, each would be £500, so the late filing total reaches £2,000 before any late payment penalties or interest.

What happens if you pay late too?

Late payment penalties are a separate charge of 5% of the tax still unpaid at each trigger date. HMRC’s Self Assessment Manual at SAM61390 shows the trigger is 30 days after the due date, with later triggers 5 and 11 months after that. For a non-leap February, the dates for 2027 are:

  • tax unpaid at the end of 2 March 2027: 5% penalty
  • tax unpaid at the end of 2 August 2027: a further 5%
  • tax unpaid at the end of 2 February 2028: a further 5%

Interest also runs from 1 February 2027 on any unpaid tax. The late payment interest rate is 8.00% from 24 November 2026. Our guide to HMRC late payment interest explains how it is worked out, and the late payment interest calculator does the sums.

Do the new penalty points apply to January 2027?

No. HMRC’s guidance on penalties for Making Tax Digital for Income Tax says that even people who joined MTD on 6 April 2026 face the current penalties on their 2025 to 2026 return due 31 January 2027.

The points-based system applies to everyone who files a personal Self Assessment return from April 2027. Read our explainer on HMRC penalty points for how points and the £200 penalty work.

Which applies to you?

  • If you file by 31 January 2027, there is no late filing penalty, even if you cannot pay in full.
  • If you file in February, March or April 2027, the penalty is £100.
  • If you file between 1 May and 31 July 2027, add £10 for each day from 1 May, up to £900.
  • If you file from 1 August 2027, add 5% of the tax due or £300.
  • If you have a reasonable excuse, you can appeal, but you must file as soon as the excuse ends.

What to do now

  1. Check that you are registered and have your UTR. Our guide on how to find your UTR explains where it appears.
  2. Gather your records and file early, ideally before Christmas, to avoid January queues.
  3. File on time even if you cannot pay. Filing removes the late filing penalties, and you can ask HMRC for a Time to Pay arrangement for the bill.
  4. If you get a penalty notice, check the dates. If you had a reasonable excuse, appeal online or on form SA370. Our guide to what HMRC accepts as a reasonable excuse has examples.
  5. Pay any penalty within 30 days of the notice. Our guide on how to pay an HMRC penalty gives the bank details and reference.

Frequently asked questions

What is the penalty for filing a tax return one day late?

The penalty is £100. It applies to a 2025 to 2026 return filed online after 11:59pm on 31 January 2027, even if you owe no tax.

When do the £10 daily penalties start?

They start on 1 May 2027 if the return is still not filed, and run for up to 90 days. The maximum is £900.

Can I get a penalty if I owe no tax?

Yes. The £100, the daily penalties and the £300 minimums all apply even if no tax is due, so a return 12 months late can cost £1,600.

Do I get a penalty if I file on time but pay late?

You do not get a late filing penalty. You pay interest from 1 February 2027 and a 5% late payment penalty on tax still unpaid at the end of 2 March 2027.

I missed the 31 October paper deadline. Am I already penalised?

No, as long as you file online by 11:59pm on 31 January 2027. The online deadline is the one that counts for a return you were asked to file by 31 October 2026.

Sources

Rates, thresholds and rules in this guide were checked against HMRC and GOV.UK guidance on 6 November 2026. Tax rules change, so check the current position on GOV.UK or with a qualified adviser before acting. This guide is general information, not personal advice.