With just eight days left before the Self Assessment deadline on 31 January, millions of taxpayers across the UK are running out of time to file without facing an automatic penalty.
More than 8.6 million people have already submitted their return for the 2024 to 2025 tax year, but a further 3.3 million are still outstanding as the final week approaches.
HM Revenue and Customs says anyone who misses the deadline will receive an immediate £100 fine, even if they do not owe tax or have already paid what is due.
The cost of delay rises steadily, with daily penalties beginning after three months and further charges added at six and twelve months, alongside interest on any unpaid balance.
HMRC is encouraging anyone who has not yet started to file now rather than waiting for deadline day, pointing to online guidance, webinars and video support that remain available around the clock.
Once a return is submitted, paying any tax owed can be done quickly through the HMRC app, which allows payments to be made in under a minute.
Myrtle Lloyd, HMRC’s Chief Customer Officer, said filing early removes pressure and gives people time to organise payment if needed.
“Don’t leave it until deadline day because filing now gives peace of mind and allows time to arrange payment if tax is due.
“If you’re worried about paying your tax bill, you may be able to set up a payment plan online, search ‘difficulties paying HMRC’ on GOV.UK.”
She added that people worried about paying their bill may be able to set up an online payment plan depending on their circumstances.
This year the deadline falls on a Saturday, meaning phone lines will close at 6pm on Friday 30 January and will not reopen until after the deadline has passed.
Webchat support will still be available on Saturday 31 January through HMRC’s Online Services Helpdesk.
Taxpayers are also being warned to stay alert to scams, with HMRC stressing it will never ask for personal or financial information by text or email.
Looking ahead, sole traders and landlords earning more than £50,000 will be required to use Making Tax Digital for Income Tax from 6 April 2026, submitting quarterly updates of income and expenses.
HMRC is urging those affected to prepare early by signing up now and familiarising themselves with the new system.
Customers are also reminded that Winter Fuel Payments received in Autumn 2025 do not need to be included in the 2024 to 2025 tax return.
For anyone who does miss the deadline, HM Revenue and Customs has set out clear penalties which apply automatically and increase the longer a return remains outstanding.
An initial £100 fixed penalty applies as soon as the deadline passes, even if there is no tax to pay or the bill itself is settled on time.
After three months, additional daily penalties of £10 begin to apply, rising to a maximum of £900.
After six months, a further penalty of 5 percent of the tax due or £300 is added, whichever is greater.
After twelve months, another charge of 5 percent or £300 applies, again whichever amount is higher.
Separate penalties apply for paying late, with charges of 5 percent added to any unpaid tax at 30 days, six months and twelve months.
Interest is also charged on any tax that remains unpaid after the deadline, in addition to the penalties already applied.
HMRC says it will consider individual circumstances, and customers with a reasonable excuse for missing the deadline may avoid a penalty.
