About 85 per cent of GPs nationwide have saved Medicare over $350 million from undercharging patients in consultations, a new study has found.

Of the 2760 GPs canvassed in the study, nearly 85 per cent undercharged Medicare for at least one consultation within a sample of 40 consultations.

Researchers from the University of Sydney estimated the undercharging by GPs has resulted in savings of $351.7 million to Medicare in 2021/22 over about 90,000 consultations.

The study published in the Australian Journal of General Practice also found GPs undercharged about 12 per cent of total consultations and only overcharged 1.6 per cent overall.

"Our study has shown that GPs are more likely to err towards undercharging, than to overcharging," said lead author Christopher Harrison.

"This contrasts with previous research and reports alleging widespread fraud related to GP billing of Medicare.

"General practice is in crisis. Allegations of fraud have been damaging to a workforce that is struggling to attract medical graduates to general practice."

Dr Harrison said a major reason why GPs undercharge, even for long consultations, is the fear of being audited.

The paper analysed data from the Bettering the Evaluation And Care of Health (BEACH) program, a national study of GP clinical activity in Australia that ran from 1998 to 2016, concentrating on the years 2013 to 2016.

Each year, a different group of 1000 GPs recorded information on paper about their consultation sessions for 100 consecutive consenting patients.

The data was used to calculate the cost differences between the Medicare Benefits Schedule (MBS) items charged and the MBS items that could have been charged based on the length of the consultation.

The results from the analysis were projected to the total number of MBS items claimed in 2021/22 using the July 2022 rebates.

Health has been put at the top of the priority list for federal, state and territory leaders with the prime minister planning to reform the Medicare system.

Last month, Anthony Albanese said better policy, not necessarily more funding, was key to fixing issues in the Medicare system.

"We all agree ... part of the issues are people turning up at emergency departments because they don't have other options," Mr Albanese said.

"We need to improve primary health care (and) we need to improve access to GP services."