Data analysed by the company, which helps individuals with their tax returns and provides self-assessment software, found that close to 12% of the 11.5 million people who needed to complete a self-assessment form left it to the last 48 hours before the January 31 deadline. Meanwhile, thousands left it to the last minute.

Individuals who file their self-assessment tax return late receive a £100 fine from HMRC, even if they don’t owe any tax. Those who do not file for a further 90 days get fined £10 per day. After this, they will be fined £300 or 5% of the tax owed – whichever is the higher amount.

“If you missed the deadline, our advice is don’t panic. There’s no real way of avoiding the £100 fine but if you file ASAP, you can avoid further financial penalties,” said GoSimpleTax’s technical director Mike Parkes.

GoSimpleTax also pointed out that in their experience many individuals fail to claim correctly for fuel, phone costs, car servicing, car insurance and use of a home office.

For example, some people miss out on claiming an average of £600 per year in fuel expenses, while leaving phone costs out of claims results in a loss of £450 on average.