Around one million individuals are facing a £100 penalty, with the potential for additional charges, after missing the self-assessment tax deadline.
HM Revenue and Customs (HMRC) revealed that 11,489,825 returns were submitted by the 31 January cut-off.
This figure encompasses expected submissions, voluntary declarations, and late registrations.
The tax body estimates that approximately one million taxpayers failed to meet the deadline. HMRC noted that these figures are provisional and may be subject to further adjustments once all data has been fully ratified.
Charlene Young, a senior pensions and savings expert at AJ Bell, said: “An estimated one million people failing to file could net HMRC £100 million in automatic fees alone.
“There is an automatic £100 fine for late filing.”
HMRC said that, among those who filed their 2024-25 return to beat the deadline, 475,722 taxpayers waited until the final day on Saturday to file their return.
This included 27,456 people who submitted returns between 11pm and 11.59pm, in the final minutes before the deadline at the end of the day.
The busiest hour on the day for submitting a return was 5pm to 5.59pm, when 32,982 people filed.
HMRC advisers handled 5,409 webchats and 10,483 calls to its helplines on the day.
Anyone who needs to file a return and missed the deadline should meet their tax obligations as soon as possible, as late filing and late payment penalties are charged, HMRC said.
People may be able to avoid a penalty if they have a reasonable excuse for filing late.
Time to pay arrangements are available for those who cannot pay their tax bill in full, if they meet the relevant criteria.
Ms Young said: “If you don’t have an excuse to appeal a fine but still owe money, you might still be able to set up a payment plan to get back on track.
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“It’s essential you don’t put your head in the sand.”
Myrtle Lloyd, HMRC’s chief customer officer, said: “Thank you to the millions of people and agents who filed their self-assessment tax return and paid any tax owed by January 31.
“Anyone who missed the deadline should file their return as soon as possible, as penalties and late payment interest may be charged.”
People will be able to file their self-assessment tax return for the 2025-26 tax year from 6 April 2026.


