HMRC insists tax crackdown 'unchanged' despite MPs' action

She said: "Whilst it is clearly important for HMRC to have adequate powers to combat deliberate evasion and aggressive tax avoidance, the increase in HMRC’s powers over the last few years has in some areas been disproportionate to the risk.

"In addition taxpayer safeguards have not kept pace, meaning that any disagreement between HMRC and taxpayers has become increasingly one-sided."

Andrew Hubbard, tax specialist at RSM said a "broad range" of taxpayers had used these strategies, from investment bankers, to people in jobs such as teaching and nursing, where the employer may have been the driving force for entering employees into the schemes, with the employees not understanding what was happening. 

Mr Hubbard said: "HMRC have always said these schemes were tax avoidance and didn't work. But HMRC's view is that this isn't retrospective because it relates to loans outstanding in this tax year."