The number of people required to fill out a tax return in the UK has hit a record high, as more people take the self-employed route.

Figures released by HM Revenue & Customs (HMRC) this week revealed 11.7m people were required to submit a self-assessment return and pay tax due by 31 January – a substantial increase on last year’s previous record figure of 11.5m.

Plenty of people left it to the last minute, however. According to HMRC more than 700,000 submitted their tax returns on deadline day, with 26,562 completing the forms between 11pm and 11:59pm on 31 January. Some 10.4m people submitted their return online, representing another record.

“The record number of tax self-assessments filed reflects the rise and rise of the self-employed sector,” Alasdair Hutchison, policy development manager at the Association of Independent Professionals and the Self-Employed, told The Financial Times.

“The record number of self-assessments isn’t just because of the rise in the number of people who define themselves as self-employed,” he added. “It’s also because more and more people now have side hustles alongside other work.

“Online platforms and other emerging technologies make it easier than ever before for people to top up their income by running their own business on the side. Many people even use this as a way to test the water before they take the leap into full self-employment.”