HMRC Self Assessment deadline fallout as 1million face fines

HMRC confirmed that 11.48 million people filed on time for the 2024 to 2025 tax year, with 97.25% of returns submitted online. However, missing the deadline comes at a price.

Late filers are hit with an automatic £100 penalty, even if no tax is owed, meaning the Treasury is already on course to collect around £100 million before additional charges begin to stack up.

The pressure was clear on deadline day itself. HMRC revealed that 475,722 people waited until the final day to submit their return, with 27,456 filing in the final hour before midnight.

The busiest hour was between 5pm and 6pm, when nearly 33,000 returns were submitted. HMRC helplines were even opened on a Saturday, with advisers handling 10,483 calls and 5,409 webchats to help taxpayers beat the clock.

11.48m people beat the Self Assessment deadline – if, you were one of them, thank you!

Anyone who missed the deadline should file their return and pay as soon as possible to avoid any further penalties.

File and pay online now: pic.twitter.com/T17tTVGp3L

— HM Revenue & Customs (@HMRCgovuk) February 3, 2026

Myrtle Lloyd, HMRC’s Chief Customer Officer, says: “Thank you to the millions of people and agents who filed their Self Assessment tax return and paid any tax owed by 31 January.

“Anyone who missed the deadline should file their return as soon as possible, as penalties and late payment interest may be charged. HMRC digital channels are always the quickest and easiest way for people to sort their tax affairs.”

For those who delay further, the costs rise sharply. After three months, daily penalties of £10 apply, followed by additional fines after six and 12 months. Late payment penalties of 5% are added at 30 days, six months and 12 months, with interest charged on top.

Tax experts warn that more people than ever are being pulled into Self Assessment, increasing the risk of missing deadlines.

Richard Major, Head of Private Client at Azets UK, says: “The full impact of more taxpayers facing the self assessment dragnet is still not clear.

“Those who haven’t filed are now building up potentially significant Government fines and credit score issues as an understandable error can quickly snowball into something more costly, with the total owed potentially reaching more than £1,000.”

He adds: “As more of us become liable for self assessment, by the time some newly affected taxpayers realise the deadline has passed, months of penalties may be liable for urgent payment. It pays to check and take action early.”

Recommended reading:

What to do if you’ve missed the HMRC self-assessment deadline

HMRC is urging anyone who missed the deadline to file immediately and pay what they owe to reduce further penalties.

Returns can still be submitted online via GOV.UK, payments can be made through the HMRC app, and Time to Pay arrangements may be available for those struggling to pay in full.

With digital filing now the norm and penalties escalating quickly, the warning to taxpayers is clear. Ignore the deadline, and the cost can rise far faster than many expect.