Jeremy Hunt has ordered Treasury officials to look into how much could be raised by closing the non-dom tax loophole for the super rich.
It came as the Chancellor was grilled by MPs over last week's Autumn Statement in which he outlined £55billion in tax hikes and spending cuts.
The controversial non-dom status - once held by PM Rishi Sunak's wife - allows wealthy UK residents not to pay tax on their overseas income.
Labour has repeatedly called for the loophole to be abolished - a move that has been resisted by Tory governments.
Mr Hunt told MPs said he had asked Treasury officials to "look into" how much could be raised by ending the non-dom status.
But he disputed claims it could raise £3billion per year and argued he would rather the super rich "stayed here and spent their money here" than abroad.
The Chancellor said: "Ireland has a non-dom regime. France has a non-dom regime.
"These are people who are highly mobile, and I want to make sure that we don't do anything that inadvertently loses us more money than we raise."
During Prime Minister's Questions on Wednesday Keir Starmer also accused Mr Sunak of protecting non-doms while "clobbering" working people.
The Labour leader said the PM was "too weak" to take on his party.
He added: "The failure of the last 12 years and the chaos of the last 12 weeks are compounded by the decisions he is taking now.
"He won't follow Labour's plan to scrap non-dom status. Instead we have got an NHS staffing crisis."
Mr Sunak replied: "He talks about leadership, this summer I stood on my principles and told the country what they needed to hear even though it was difficult. When he ran for leader, he told his party what they wanted to hear.
"Even now, he says one thing and he does the other. He says he cares for working people, but he won't stand up to the unions.
"He said he'd honour Brexit but he tried to have a second referendum, and now he tries to talk tough about immigration but he promised to defend free movement."
The PM's wife, Akshata Murty, was forced to say in April she would pay UK taxes on all her worldwide income after facing criticism over her non-dom status.
