Any strike action is likely to take place in the spring with customer services, tax and anti-fraud investigations as well as work at customs checking centres all potentially impacted.

HMRC recently admitted it will fail to collect billions in unpaid tax that it has been owed for “some years”. This week, the public accounts committee released a report revealing HMRC had failed to collect £42 billion in taxes last year — some 5% of the UK’s tax burden — of which £4.5bn was stolen or wrongly claimed through Covid support schemes.

In its annual report for 2021-22, HMRC said: “The tax debt balance is likely to remain above the pre-pandemic average of 2.4% of tax revenues for some years.”

Pre-pandemic unclaimed taxes were consistently at around £20bn, After which it grew more than three-fold to £70bn in August 2020 as HMRC insolvencies and debt-collection activities were paused and some were allowed to defer tax bills.

A HMRC source claimed the strike action was “more than highly likely” to be voted in favour and one in three staff are considering resigning, The Times reports.