COMEDIAN Jimmy Carr apologised for a "terrible error of judgment" after avoiding tax on £3.3million of income as it emerged the Scottish tax advisers who promoted the scheme would have been paid £600,000.

David Cameron was criticised yesterday for publicly condemning Carr and his "dodgy" tax avoidance scheme but failing to do the same with Tory-supporting pop star Gary Barlow, who has also been accused of sheltering tax.

As Carr said yesterday he had withdrawn from the tax avoidance system, The Herald established that Kirkcaldy-based Peak Performance, which created the K2 avoidance scheme used by Carr among 1100 clients, will have pocketed commission of up to 15% on the cash it nets for the scheme. A further 3% commission is paid to small accountancy firms that promote the scheme around the UK. That would have landed Carr with a bill of up to £594,000 on the £3.3m he is said to have invested in K2.

HMRC has now said it is looking into such schemes and will challenge them "in every way available".

Richard Brunton, head of tax at HBJ Gately Wareing in Edinburgh, said: "It's very likely the Revenue will go at it, given the situation. It will end up at the tax tribunal and if they are successful, the tax will be payable for each year covered."

Aidan McLaughlin, partner at Glasgow-based advisers McLaughlin Crolla, said: "Carr's tax bill would be well in excess of £1m and it remains to be seen whether he would be able to recoup some of the not inconsiderable commission he will have paid Peak Performance. Assuming the scheme was initially disclosed to HMRC, there ought not to be any penalty, though late payment of tax carries interest."

Mr McLaughlin said "mainstream firms" would not "touch" K2, although "one or two" in London in the sports or entertainment business might.

Peak Performance was set up by David Gill, formerly of accountants RSM Tenon. The Herald revealed in 2010 that Tenon's specialist tax division, Premier Strategies, was attracting around £250m a year into its avoidance schemes. However, RSM Tenon told the Stock Exchange last month that due to the Chancellor's threat to introduce a new anti-avoidance rule from March 2013, Premier would withdraw from the market.

The consultancy declared a profit of £37,607 in its last published accounts a year ago. Mr Gill and fellow director Douglas Aitken were both unavailable for comment again yesterday.

Paul Renz, tax partner at Scott-Moncrieff in Edinburgh, said: "Over the years we have seen promoters approaching individuals offering schemes which, on the face of it, produce significant tax savings. These promoters tend to emphasise the benefits without properly explaining the risks involved."

The PM said yesterday he had criticised Carr and not Barlow because the comedian's was a "particularly egregious example of an avoidance scheme that seemed to me to be wrong".

Labour MP Angela Eagle said if Barlow's actions were also morally repugnant "why has he been given an OBE? Why is the Prime Minister's view of what's dodgy in the tax system so partial?"