Brits could face being hit with an “unexpected” tax bill by HMRC. Thousands of businesses and self-employed people face the possibility due to a little-known deadline. HMRC figures show 737,891 taxpayers completed their Self Assessment returns during April 2026.
Easter Monday proved particularly busy, with 86,270 people filing their 2025/26 returns on April 6. But Ridgefield Consulting, tax experts, says early submission rates are masking a problem: a lack of knowledge among four groups (those who freelance, have rental income, do side-hustles, or have second jobs). Countless workers and business owners are urged to meet an approaching deadline set by His Majesty’s Revenue and Customs (HMRC). The July 31 date applies to anyone required to make “payments on account” as part of a tax Self-Assessment.
HMRC’s “payments on account” scheme represents one of the most common sources of shock, experts say.
Payments on account are advance payments towards next year’s tax bill.
If this is the first time you need to make payments on account, they can be surprising – and a little confusing.
Simon Thomas, the managing director of Ridgefield Consulting, said: “We see many business owners and self-employed workers experiencing the stress of an unexpected HMRC bill arriving, particularly where payments on account increase what they are expecting to pay.
“The key issue is often cash flow rather than compliance; people aren’t necessarily doing anything wrong, they just haven’t planned for how the system works.”
Mr Thomas added: “The worst thing taxpayers can do is ignore the issue and wait for payment deadlines to pass.”
Rachel Harris said many taxpayers fall into the same cycle every year by filing in January and then ignoring their finances for the next 12 months.
She said: “HMRC absolutely hate it when people do this, and so many of you do it. Once they file their tax return in January, they close the tab, don’t look at their numbers again, while simultaneously promising themselves they’ll do it differently next year.
“And I know it’s not because you’re lazy or bad with money. It’s because tax has become set up as a once-a-year scramble.”
Myrtle Lloyd, HMRC’s Chief Customer Officer, said: “For thousands of people, filing early and staying on top of their finances has become the norm.
“It takes the pressure off in January and means they can spend their time focusing on their business and doing things they love.”
