HMRC will earn at least £100million in late penalty charges after an estimated 1million people failed to submit tax returns in time for the 31 January 2026 deadline.
The windfall for the Treasury comes as a result of automatic £100 late filing penalties levied on those who missed the deadline.
HMRC issues penalty charges even if no tax is owed but you are registered for Self Assessment.
Last year, 1.1 million faced penalty charges for missing the deadline.
The £100million figure is likely to further increase as late filers also face daily penalties and interest charges in February.
HMRC has previously collected as much as £200million from penalties after these extras take effect.
The taxman said 27,456 people submitted returns within the hour before the deadline
After three months, HMRC adds £10 per day, up to £900, while after six months the greater 5 per cent of the tax due or £300 is charged.
After 12 months another 5 per cent or £300 is charged.
HMRC said 11.48million people did file their tax returns by the deadline. This included 475,722 taxpayers who waited until the final day before they submitted their tax return.
The taxman said 27,456 people submitted returns within the hour before the deadline.
Myrtle Lloyd, HMRC’s chief customer officer, said: ‘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.’
Charlene Young, of AJ Bell, said: ‘Taxpayers with gains to report had an added challenge this year.
‘The main rates of capital gains tax increased to 18 per cent for basic rate taxpayers and 24 per cent for those paying higher rates on 30 October 2024.
‘The mid-year change meant some people risked underreporting and underpaying any tax they owe for 2024/25, or having to navigate an extra online calculator if they rely on HMRC’s systems – perhaps because they file without the help of commercial software or an accountant.
Accountancy firm Azets says frozen tax thresholds, higher savings interest and more landlords and pensioners on the higher tax rate being required to submit Self Assessment forms is likely to push up the number of people who miss the deadline each year.
Richard Major, of Azets, said: ‘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.’
Those who think they have grounds to appeal the penalty can do so via the gov.uk website. You can ask HMRC to cancel the penalty if you are not required to send a tax return.
Young said: ‘It’s often worth paying the initial penalty, even if you’re planning to appeal.
‘Although it involves shelling out cash, it avoids you paying interest on the penalty itself from the date it became due if you lose your appeal.
‘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. It’s essential you don’t put your head in the sand.’
