In June, HMRC said it had collected the wrong amount of tax from 5.5 million people in the year to April 2014 despite the introduction of a new computer system aimed at making the process more efficient and accurate.
Those affected were sent notification letters explaining how HMRC would get back tax owed or issue a refund for around £300 on average.
But according to a report in The Daily Telegraph a leaked email yesterday revealed a select group of HMRC staff had been informed that thousands of mistakes had been made.
The email said: “We are urgently investigating these cases and will look to resolve the matter in the next six to eight weeks. We currently do not know the scale of the issue but some large employers are involved, so several thousands of employees may be affected.”
The Telegraph quoted whistleblowers as saying that those affected by the error could “easily run into the hundreds of thousands”. One said: “HMRC refuses to admit the system doesn’t work, and it’s scandalous that there is no politician holding them to account as the whole programme of welfare reform could be put at risk because of this.”
A spokesman for HMRC said: “HMRC issued a small number of incorrect 2013-14 tax calculations over a three-week period from 15 September. This issue only affects a small proportion of the 2013-14 P800s and payable orders which were issued in this period. The error was based, in part, on incomplete information from employers and is limited to Income Tax only. We are urgently looking into what has happened in order to resolve this issue, and we are sorry for any worry or inconvenience caused.”
