London, Jan 6, 2026, 12:16 GMT
- HMRC says 5.65 million people still need to file 2024/25 Self Assessment returns before Jan. 31
- Missing the deadline triggers a £100 fine, with further penalties and interest for late filing or payment
- Some self-employed taxpayers also face “payments on account” — advance instalments toward next year’s bill
Britain’s tax authority said 5.65 million people still need to file their Self Assessment tax return with less than a month to go before the Jan. 31 deadline. More than 6.36 million have already submitted a return, HM Revenue & Customs said on Monday. 1
The filing date matters because it is also the deadline to pay any tax owed for the 2024/25 tax year. Anyone who misses it faces an automatic £100 late-filing penalty, even if they end up owing no tax, HMRC said.
The push comes as HMRC prepares to widen its “Making Tax Digital” programme, which requires some self-employed people and landlords to keep records in recognised software and send quarterly updates to the tax authority. From April 2026, the shift begins for those with combined turnover from self-employment and property above £50,000, according to HMRC’s campaign guidance. 2
Myrtle Lloyd, HMRC’s chief customer officer, urged people not to leave it late. “If you have yet to start, the clock is ticking,” she said.
HMRC highlighted a New Year surge in filings, saying 54,053 customers filed on New Year’s Eve and New Year’s Day. Of those, 342 submitted in the final hour of 2025, while 19,789 filed on New Year’s Day.
The tax authority said people can start a return online, save it, and come back as often as needed before submitting. It also pointed taxpayers to the HMRC app as an easy way to make payments and set up reminders.
HMRC said late filing penalties start with the £100 fixed fine, then rise after three months with daily penalties of £10 per day up to £900. After six months, it said a further penalty of 5% of the tax due or £300 applies, followed by another 5% or £300 charge after 12 months.
Late payment brings its own penalties, HMRC said, including charges of 5% of unpaid tax at 30 days, six months and 12 months, plus interest on overdue amounts. HMRC added that people who cannot meet the deadline should tell it before Jan. 31 and that it will treat “reasonable excuses” fairly.
For many self-employed people and landlords, the bill can also be larger than expected because of “payments on account” — advance instalments towards the next year’s tax, usually split into two payments due on Jan. 31 and July 31. Under HMRC’s rules, first-time filers who are required to make payments on account may have to pay the full tax due plus an upfront instalment for the following year, effectively 150% of the year’s bill, with the second instalment due in July. 3
