A proposal to introduce an up-front $6 fee to visit a general practitioner has been criticised by the Australian Medical Association (AMA).

A Commission of Audit, set up by Prime Minister Tony Abbott, has received a submission recommending the co-payment system for GP visits.

Under the proposal, pensioners and concession card holders would be exempt from the fee, while families would be granted up to 12 bulk-billed visits annually.

The Federal Government says the new fee is one of several recommendations currently on the table but no decisions have been made.

"The government has committed to funding in health and to making sure our health system is sustainable and accessible into the future," Health Minister Peter Dutton said in a statement.

"We won't be commenting on speculation around what the Commission of Audit may or may not recommend.

"The Commission's work is still being compiled and will be provided to the Government in 2014."

But the AMA says the plan would discourage people from visiting a doctor if they are sick.

"There's clearly a need to rein in costs, but I think this may not be the area they do want to look at," AMA president Dr Steve Hambleton said.

"There are plenty of people now who actually have to choose, 'Do I go to the doctor? Do I get a prescription?'

"If they had to choose again because there was more money required to actually access healthcare, we may find people not going to the doctor who need to go."

Dr Hambleton says people who are unwell should be encouraged to see a doctor early.

"Anything that dissuades people from being at their GP, getting good advice, keeping those chronic diseases in check and staying well, would be a concern," he said.

PM should rule out any new fee, Labor says

Terry Barnes, a former senior policy advisor to Mr Abbott while he was health minister in the Howard government, authored the report outlining the measure.

He says it would change the way people think about visiting a doctor.

"You would basically be asked the question, do I really need to go to the doctor for this? Could I just look after myself?

"People don't always need to see a doctor for things that they see a GP for, particularly minor things like coughs and colds and particularly flu in the winter."

But the Federal Opposition says the fee proposal would effectively end the ability to visit a doctor for free in Australia.

Labor's health spokeswoman Catherine King says taxpayers expect free medical care when they pay the Medicare levy.

"I think when people are sick, they need to be able to access medical care. We already pay for medical care through the Medicare levy," she said.

"Tony Abbott is now proposing that people should pay even more to visit a doctor, no matter how sick they are."

Labor Senator Penny Wong says the Prime Minister will break his promise of no new taxes if he introduces a charge for GP visits.

"Did Tony Abbott mention this before the election? Did he tell Australians that he was planning on introducing a new tax on doctors visits for sick children and ill families?" Senator Wong said.

"I don't think he did and that's the reality. It's another broken promise from the Prime Minister."