The Lib Dems have demanded an investigation into whether and when Rishi Sunak ever held a US green card if he fails to “come clean”.
Sky News reported that the chancellor and his wife Akshata Murty held green cards, permitting US residence, until more than a year into his time in No.11.
The US inland revenue says anyone who has a green card is treated as a lawful permanent resident and is considered a “US tax resident for US income tax purposes”.
Ed Davey, the Lib Dem leader, has written to cabinet secretary Simon Case and the independent adviser on ministers’ interests Lord Geidt, urging them to open an investigation.
“How could the man who is responsible for UK tax policy regard any permanent residency status for the United States as acceptable?” he said.
“This would be a huge conflict of interest - and a serious breach of the ministerial code.
“Rishi Sunak must come clean about his own financial arrangements and whether he has ever held a green card.
“If he will not, then we need an independent investigation to get to the bottom of this.”
Sunak’s office and the Treasury have have been contacted for comment.
It comes after Murty, the fashion-designer daughter of a billionaire, who married the chancellor in 2009, confirmed she holds non-dom status following a report by The Independent.
Murty, who is estimated to be worth hundreds of millions of pounds, had done nothing wrong by choosing the arrangement exempting her from paying tax in the UK on foreign income.
In an interview with The Sun, Sunak accused his critics of trying to “smear my wife to get at me”.
“Every single penny that she earns in the UK she pays UK taxes on, of course she does,” he said.
“And every penny that she earns internationally, for example in India, she would pay the full taxes on that.”
Labour leader Keir Starmer has said Sunak could be guilty of “breathtaking hypocrisy” if his wife was reducing her own tax bill as the chancellor increased national insurance for millions of Britons.
Sunak has blamed Labour for the briefing against him and his wife. But the Daily Telegraph reported that unnamed allies of the chancellor claimed Boris Johnson’s office were behind the leaks – an allegation No.10 and No.11 strongly denied.