Some 5.65m people have yet to file their self-assessment tax return despite the end-of-January deadline approaching, HMRC has warned.

Those who miss the deadline could face an initial late filing penalty of £100 plus further fines.

Figures released by the tax authorities show that 6.36m people filed at least a month ahead of the deadline, with tens of thousands spending New Year’s Eve or New Year’s Day completing their forms.

Some 54,053 taxpayers filed their tax return for 2024/2025 on New Year’s Eve and New Year’s Day with 342 people filing in the last hour of 2025.

Almost 4,000 - 3,927 - people filed between 11am and 12pm on 31 December – the most popular time to file over the two days while 19,789 missed their traditional New Year’s Day walk or day in front of the TV to file their tax return instead.

Myrtle Lloyd, HMRC’s chief customer officer, said: “New Year is a great time to start afresh. What better way than to ensure your tax affairs are in order for another year than completing your tax return.

“If you have yet to start, the clock is ticking, go to GOV.UK and start today.”

Customers who are unable to meet the tax return deadline need to tell HMRC before 31 January. HMRC said it will treat those with reasonable excuses fairly.

The penalties for late tax returns are:

• an initial £100 fixed penalty, which applies even if there is no tax to pay, or if the tax due is paid on time
• after three months, additional daily penalties of £10 per day, up to a maximum of £900
• after six months, a further penalty of 5% of the tax due or £300, whichever is greater
• after 12 months, another 5% or £300 charge, whichever is greater

There are also additional penalties for late payments of 5% of the tax unpaid at 30 days, six months and 12 months. If tax remains unpaid after the deadline, interest will also be charged on the amount owed, in addition to the penalties above.