If Home Affairs Minister Peter Dutton is referred to the High Court to test his eligibility he's warned other MPs will also head there in his wake.
He also says he has nothing to do with his wife's childcare businesses, and they do not make profits from government payments passed on to parents.
Labor has sought to refer Mr Dutton to the High Court to test whether he is eligible to sit in parliament under Section 44 of the constitution, which bans people making a profit from federal funding.
"The legal advice from two QCs has been very clear, that is there's not an issue," Mr Dutton told reporters in Canberra on Wednesday.
The question arose after it was revealed Mr Dutton's family trust has a financial interest in childcare centres, which receive government funding that is then passed onto parents.
"If there's an issue with a service receiving a childcare benefit through a parent, then every doctor is in doubt because MBS (Medicare Benefits Schedule) becomes an issue, every pharmacist is in doubt because of PBS payments," he said.
That could mean new Wentworth independent Kerryn Phelps is in danger due to her local GP practice.
In the case of special needs children, Mr Dutton says his wife makes a loss even after extra federal funding is provided.
"When Kirilly takes kids in, as she tells me, with special needs into her centre, they lose money in relation to that arrangement," he said.
"The advice to me has been very clear, that is if there's not a profit made out of the transaction, then there's not a section 44 issue."
Mr Dutton, who missed two weeks of parliament due to an arm injury, said he was "very certain" of his legal position.
"My wife's business interests are her business interests. I've not received a dollar of distribution from that trust," he said.
"I don't have any operational involvement. I speak to my wife at night time, she'd say I don't listen well enough to what's happened during her day at work.
"I just have nothing to do with it. Out of an abundance of caution, in any (cabinet) discussion I've recused myself."
