Rishi Sunak has admitted holding a US green card while chancellor but his spokesman has insisted all rules have been followed.
It follows Sky News reporting earlier that the chancellor and his wife held US green cards – permitting him residence in the country – until more than a year into his time at 11 Downing Street.
Green card holders must pay US tax on their worldwide income and pledge that the US is their forever home.
A spokeswoman for the chancellor said: “Rishi Sunak had a green card when he lived and worked in the US.
“Under US law, you are not presumed to be a US resident just by dint of holding a green card. Furthermore, from a US immigration perspective, it is presumed that permanent resident status is automatically abandoned after prolonged absences from the US.
“At the same time, one is required to file US tax returns. Rishi Sunak followed all guidance and continued to file US tax returns, but specifically as a non-resident, in full compliance with the law.
“As required under US law and as advised, he continued to use his green card for travel purposes. Upon his first trip to the US in a government capacity as chancellor, he discussed the appropriate course of action with the US authorities. At that point it was considered best to return his green card, which he did immediately.
“All laws and rules have been followed and full taxes have been paid where required in the duration he held his green card.”
Prime Minister Boris Johnson had earlier insisted that Rishi Sunak had done “absolutely everything” required after it was reported he held a US green card for a period while chancellor.
He told a Downing Street press conference: “As I understand it the chancellor has done absolutely everything he was required to do.”
Mr Johnson also denied that Number 10 has been briefing against Mr Sunak over his wife’s non-dom status.
“If there are such briefings they are not coming from us in Numer 10 and heaven knows where they are coming from,” the Prime Minister told a Downing Street news conference,” he said.
“I think that Rishi is doing an absolutely outstanding job.”
