Last week, HM Revenue & Customs warned that more than three million people had yet to complete their 2016/2017 tax returns. The deadline is 31 January.

The Federation said that small businesses had been hit because they could no longer spread tax payments by paying their bill on a personal credit card. HMRC banned this type of payment earlier in the month because it can no longer pass on bank charges for processing the payments. At the same time, the option to pay self-assessment bills at post offices was also removed.

Mike Cherry, national chairman of the Federation of Small Businesses, told The Times: “Filing a self-assessment tax return has been even more challenging than usual this year. It’s been hurdle after hurdle. Rather than threaten vulnerable small firms with fines, HMRC should be exercising flexibility around Wednesday’s deadline for those affected.”

He said he wanted to see HMRC apply ‘flexibility and a common-sense approach’ to those unable to meet the deadline.

At the same time, a survey by online accounting group Crunch found the self-employed work on average an additional 14 hours per week, compared to those in a permanent role. The survey also found that January is the most stressful time of the year for a third (31%) of self-employed workers.