Borrowing this year has so far been much lower than expected, as a feared spike in unemployment following the end of the furlough failed to emerge amid a scramble for staff by employers.

According to the Office for Budget Responsibility (OBR), the Government’s official fiscal forecaster, the deficit is already £7.1bn below its October forecasts for the eight months to November which it attributed “to a more resilient labour market”.

Economists said the deficit could be almost £20bn below the OBR’s £183bn forecast for the current year, giving Mr Sunak ample headroom to postpone the tax rise.

Philip Shaw, chief economist at Investec, said: “The signs since October have been pretty good. The labour market remains robust, so in turn that implies that the income tax take was pretty decent.

“We are probably looking at something around £165bn or so [in borrowing]. Although you can get huge revisions to these numbers, you could argue that the OBR is relatively conservative in its forecasts.”

Martin Beck, senior economic adviser to the EY Item Club, said: “The argument that you can’t do it because of this big deficit is becoming less convincing, although the situation could deteriorate.”

A survey of businesses by the Institute of Directors (IoD) warned that nearly four in ten, or 38pc, of companies were preparing to raise prices to offset the added cost burden. One in five firms added that they would “employ fewer people”. 

Kitty Ussher, the IoD’s chief economist and a former City minister, said the national insurance rise was “of real and genuine concern” to business leaders.

She warned: “Faced with the forthcoming increase in the cost of employing their teams, many businesses are planning to raise prices to offset the cost and/or rein in on their hiring plans.”

The Treasury was approached for comment.