Jeremy Hunt has said he could refuse to pay part of Britain's £39 billion exit bill to the European Union.
The Tory leadership contender said he would "not hand over a penny more than is legally required of us" if negotiations with the EU failed.
He also revealed he would deliver a speech on Monday which will "turbocharge" plans for a no-deal exit from the bloc on October 31.
"As a businessman I always paid my bills. That being said, if we leave without a deal I will not hand over a penny more than is legally required of us," he told The Sunday Times.
"Anyone who thinks I am going to write a blank cheque to the European Union is sorely mistaken."
Mr Hunt said both he and rival Boris Johnson wish to change Britain's withdrawal agreement, but noted that he would not exit from the EU on Halloween if a deal was close.
He added: "We will know by the beginning of October if it's going to be possible to negotiate a deal that we are going to be able to get through the House of Commons. If it isn't, I'll take us out without a deal."
The Sunday Times reported that Mr Hunt had signed up former Canadian prime minister Stephen Harper to lead his Brexit negotiating team.
The team is also set to include Department of International Trade negotiator Crawford Falconer and ex-health minister of Canada Rona Ambrose.
"To break the impasse with the European Union we need a tough and skilled negotiator, not empty rhetoric," Mr Hunt told the paper.
"In Crawford Falconer you have someone who is respected as the toughest trade negotiator in the world. I'm good personal friends with Rona Ambrose. These are people who know how to get a tough deal."
Mr Harper successfully negotiated a free-trade pact with the EU, while Ms Ambrose worked on the North American Free Trade agreement after Donald's Trump election.
Meanwhile, Mr Johnson is assembling a Brexit team led by Sir Eddie Lister, the Telegraph reports.
PA understands chief Brexit negotiator Olly Robbins will quit his role shortly after the new prime minister takes up his post at the end of July.
His departure is the latest in a wave of top civil servants dealing with Brexit who have announced they will resign rather than take on the challenge of delivering Brexit within 100 days under the new leader.