The government borrowed £ 62.1 billion in April, the highest monthly figure on record, according to the Office for National Statistics (ONS).
It highlights the cost of fighting the coronavirus pandemic through employment programs and loans, and is higher than many economists have anticipated.
The cost of leave schemes had the greatest impact, reaching £ 14 billion in April.
The government’s independent forecaster, OBR, said the annual deficit could reach £ 298 billion.
April’s figure is significantly higher than analysts had expected, with a consensus of economists forecasting £ 30.7 billion for the month.
Jonathan Athow, assistant national statistician at the NSO, described the April figure as “almost unprecedented.”
He told the BBC: “Borrowing is now about six times what it used to be. [in April] so last year we are talking about really big changes in public finances. “