Around one million people missed the deadline to submit their self-assessment tax returns for the 2024–25 tax year, HM Revenue and Customs (HMRC) has confirmed, leaving them liable for automatic penalties.
HMRC reported that 27,456 taxpayers filed in the final hour before the midnight cut-off on Saturday. The tax authority extended helpline and webchat services over the weekend to assist late filers, with the busiest period for online submissions occurring between 5pm and 6pm. In total, 475,722 returns were submitted on the final day, bringing the overall number of filings to approximately 11.5 million.
Anyone failing to meet the deadline now faces an immediate £100 fine, even if no tax is due or payments have already been made. Penalties increase the longer a return remains outstanding, with daily fines of £10 after three months, capped at £900, followed by further charges at six and 12 months. Late payment of tax incurs additional 5% surcharges at 30 days, six months, and 12 months, along with interest on unpaid balances.
Myrtle Lloyd, HMRC’s chief customer officer, thanked those who filed on time and urged late filers to act quickly. “Anyone who missed the deadline should file their return as soon as possible, as penalties and late payment interest may be charged,” she said.
Self-assessment remains compulsory for individuals with additional income, including those earning more than £1,000 from self-employment or from renting out property or land during the tax year. However, some people were no longer required to file this year, such as those whose only prior reason for submitting was earning over £150,000, or parents now paying the high-income child benefit charge through PAYE.
A similar number of taxpayers missed the deadline last year. HMRC said it will consider “reasonable excuses” for late filing and may cancel penalties where appropriate.
Tax experts are urging caution, warning against delaying action. Charlene Young, senior pensions and savings expert at AJ Bell, said even those intending to appeal a penalty should consider paying it upfront to avoid accumulating interest. “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,” she added.
HMRC’s data highlights the ongoing challenges of self-assessment compliance, despite efforts to support taxpayers. The combination of automatic penalties, escalating fines, and interest underscores the importance of timely filing for individuals with additional income or other obligations under the self-assessment system.
