HMRC has warned 5.4 million taxpayers they have less than a month to complete and pay their self-assessment tax returns.

Taxpayers have until January 31 to submit their returns or risk a £100 fine.

The warning comes after more than 24,800 people filed on New Year's Day. A further 38,000 submitted theirs on December 31, 310 of which were filed between 11pm and 11.59pm.

Myrtle Lloyd, HMRC’s director general for customer services, said: "We know completing your tax return isn’t the most exciting item on your New Year to-do list, but it’s important to file and pay on time to avoid penalties or being charged interest.

"The quickest and easiest way to complete your tax return and pay any tax owed is to use HMRC’s online services – go to GOV.UK and search ‘Self Assessment’ to get started now."

Those who miss the deadline could face increasing penalties, including daily fines and a percentage of the tax due.

In addition to fines, interest will be charged on any unpaid tax after the deadline. More information can be found on the government website.