The proposal, contained in the government’s consultation document on HM Revenue & Customs powers, would see taxpayers who adopted unreasonable interpretations facing penalties of a minimum of 30% of the tax due, and a maximum of 100%.

Currently, such penalties apply only in cases of fraud or neglect.

The proposal is seen as a government attempt to crack down on flagrant attempts to use the letter rather than the spirit of the law to obtain tax deductions. It is an extension of the government’s view that avoidance should cease to be a one-way bet.

Firm proposals could appear in the pre Budget report later this year, and though the consultation suggests the move relates to tax evasion, a spokesman for HMRC said it would apply to avoidance as well.

The deadline for comments closes on Friday next week. Paul Harrison, head of investigations at KPMG, said the firm would be opposing the move in its comments.

‘We cannot see that a penalty is appropriate in these cases,’ said Harrison. ‘The current categories cover everything that ought to be penalised.’

Advisers said the move showed HMRC’s increasing reliance on US methods, where a test of whether a taxpayer feels their position is ‘more likely than not’ to succeed applies.

John Whiting of PwC cautioned the government to outline the rights as well as the responsibilities of taxpayers. ‘Like a lot of these things, this should be about a balanced package,’ he said. ‘It shouldn’t just be about giving HMRC powers.’

Richard Murphy, the anti-avoidance campaigner, said the rules would act as more of a deterrent than anything else, and suggested they were targeted at lawyers who offered opinions on tax schemes as ‘insurance’ for companies.