Around one million people missed the deadline to file their self-assessment tax return, leaving them facing automatic penalties, according to HM Revenue and Customs.

HMRC said 27,456 taxpayers filed in the final hour before the midnight cut-off at the end of Saturday, after the tax authority kept helplines open and extended webchat services over the weekend in a bid to help late filers.

The busiest period for online submissions was between 5pm and 6pm on Saturday. In total, 475,722 people filed on the final day, bringing the overall number of submissions for the 2024–25 tax year to around 11.5 million.

Anyone who failed to file on time now faces an automatic £100 penalty, even if there is no tax to pay or the tax owed has already been settled.

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 31 January. Anyone who missed the deadline should file their return as soon as possible, as penalties and late payment interest may be charged.”

While most employees pay tax automatically through PAYE, self-assessment remains mandatory for people with additional income. This includes those earning more than £1,000 from self-employment, or from renting out property or land during the tax year.

Some individuals were no longer required to submit a return this year, including those whose only previous reason for filing was earning more than £150,000, or parents who now pay the high income child benefit charge through PAYE instead of self-assessment.

A similar number of taxpayers missed the deadline last year. HMRC’s penalty regime escalates the longer a return remains outstanding. In addition to the initial £100 fine, late filers can face daily penalties of £10 after three months, capped at £900, followed by further penalties after six and 12 months.

Separate penalties also apply for paying tax late, with 5% surcharges applied after 30 days, six months and 12 months, alongside interest on unpaid balances.

HMRC said it will consider reasonable excuses for missing the deadline and may cancel penalties where appropriate. However, tax experts warn against delaying action.

Charlene Young, senior pensions and savings expert at AJ Bell, said: “Even if you intend to appeal a penalty, it’s often sensible to pay it upfront to avoid interest being added if the appeal fails. If you owe tax and can’t pay in full, a payment plan may be available — but ignoring the problem will only make it worse.”

Jamie Young

Jamie is Senior Reporter at Business Matters, bringing over a decade of experience in UK SME business reporting.
Jamie holds a degree in Business Administration and regularly participates in industry conferences and workshops.

When not reporting on the latest business developments, Jamie is passionate about mentoring up-and-coming journalists and entrepreneurs to inspire the next generation of business leaders.