Channel 4 News understands that former judge Sir Andrew Park has been asked to look into controversial decisions by the UK tax authorities to do deals with large corporations to forgive unpaid taxes.
It's believed that Sir Andrew's investigation on behalf of the National Audit Office will cover up to ten deals struck by the taxman with companies including phone company Vodafone and the investment bank Goldman Sachs.
In one agreement with Vodafone, a potential tax bill of up to seven billion pounds was waived. That decision was subsequently criticised by a whistleblower, Osita Mba, who told the Public Accounts Committee that in striking such a deal the HMRC may have over-reached its powers.
Mr Mba, a lawyer for the HMRC, has since been put on extended leave whilst the HMRC carries out an internal disciplinary investigation. His treatment has already drawn criticism from MPs on the Public Accounts Committee. Their full report into the matter is due next week.
In October Dave Hartnett, the top official at HMRC, gave evidence about a blunder that had allowed investment bank Goldman Sachs to escape paying ten million pounds in interest on a tax bill.
The interest was payable on thirty million pounds of tax due from a failed tax avoidance scheme on bankers' bonuses. Mr Hartnett is said to have personally sealed the agreement with a Goldman executive last November after being advised by an official that there was a "legal impediment" to charging interest. He later apologised for the error.
Following the furore Dave Hartnett became the personal target of demonstrations staged by 'Occupy London' protestors who called for his resignation, and it was recently announced that he would be retiring next summer.