Sir Ed Davey, the Liberal Democrat leader, called on Mr Sunak to resign and accused the Chancellor of breaking the ministerial code by failing to declare his green card and his wife’s tax status. 

Sir Ed wrote to both Simon Case, the Cabinet Secretary, and Lord Geidt, the Prime Minister’s independent adviser on standards, calling for an investigation.

“Over the past few weeks, when he should have been supporting struggling families up and down the country, he’s been hitting them with a massive tax rise,” he said. “Now it turns out he has failed to keep to the ministerial code. Never mind a green card, it’s time to give Rishi Sunak the red card.”

Mr Sunak moved to the US in 2004 to study for a Master of Business Administration at Stanford University, California. He worked in the US after completing his studies. It was at Stanford that he met his wife, whom he married in 2009.

A spokesman for Mr Sunak said he had been granted a green card while living and working in the US and kept it when he moved back to the UK, becoming the MP for Richmond, North Yorkshire, in 2015.

The spokesman said: “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.”

Mr Sunak chose to pay tax in the UK and also in the US – meaning he was taxed twice – in order to retain the green card, his spokesman confirmed.