Opposition parties are urging the tax authorities to investigate SNP MP Phil Boswell after it was claimed that he took advantage of an avoidance scheme.
It emerged that he took an £18,000 interest-free loan which he received as a result of his job as a contract manager.
There is no suggestion Mr Boswell has done anything illegal, but he has admitted the arrangement and said it was “common practice” in his previous industry.
He now plans to use his new role as an MP to highlight “treasury management issues”.
But Scottish Labour’s business manager James Kelly said the allegations are “very serious.”
Mr Kelly added: “I would urge HMRC to investigate them as a matter of urgency. The public need to have confidence that their elected representatives are playing by the same rules as everybody else.
“People will be astonished by the apparent hypocrisy of Phil Boswell, with him preaching about the evils of tax avoidance whilst appearing to have taken advantage of a tax avoidance scheme himself.
“We also need a full investigation by the SNP into this case, and an explanation as to why yet another SNP MP appears to be caught up in more financial scandal.”
It is the latest blow for the SNP’s intake of new MPs at Westminster after Natalie McGarry and Michelle Thomson were both suspended from the party following separate allegations.
Liberal Democrats peer Jeremy Purvis said the revelations were “shocking and very serious”.
“Parliamentary rules seem to have been breached in not declaring personal gain when raising, hypocritically, tax evasion schemes in Parliament,” the peer added.
“It is outrageous that he expects people on low and middle wages to pay more to make up for his personal gain by avoiding paying due taxes. I voted successfully to overturn the Tories’ tax credits cuts and it is shocking that wealthy people who have broad shoulders should think it’s acceptable to use such dodgy tax avoiding tactics. The previous coalition did much to clamp down on this kind of practice and it needs to be investigated urgently.”
Mr Boswell’s register of interest in the House of Commons discloses that he has benefited from an “interest-free” loan £18,308.82, made by Hyrax Resourcing and “now repayable on demand”.
It states that it relates to his time working as contracts manager for US energy company Phillips 66, through support services firm PDI Ltd.
He said: “Under the conditions of my contract, and entirely at the discretion of my employer, I was entitled to this discretionary interest-free loan. After previously finding myself employed in such a contract, I decided to utilise my knowledge and experience in my new role as an MP to highlight treasury management issues.”
Mr Boswell was one of the 56 MPs elected in the SNP’s rout at the Westminster elections in May after recently becoming active in politics.
He has worked for oil giants including BP, Rio Tinto,Shell and Premier Oil.
He has tabled Commons questions calling on the Chancellor to close tax avoidance schemes exploited by private equity and hedge fund managers.
The SNP also tabled an amendment in the House of Commons in October criticising the UK government for having “failed to close tax loopholes.”