A measure that has kept Medicare rebates for some services at the same rate for years - without taking into account inflation - would end a year earlier than planned under a federal Labor government.

The opposition has vowed to end the Medicare rebate indexation freeze within 50 days if it forms government after the next election, expected in May.

The freeze has been ending in stages since mid-2017, and is due to finish completely in mid-2020.

Ending the measure early will cost $213 million and mean rebates for about 100 GP items - including family counselling and mental health care - will resume going up in line with price rises across the economy.

Labor Leader Bill Shorten says the pledge is aimed at making healthcare more affordable.

"The future of Medicare was at the top of my plan in the last election, and this election will be no different," he said.

Independent MP and former Australian Medical Association president Kerryn Phelps believes Medicare will be a key election issue.

"The issue around the Medicare rebate freeze is coming to a tipping point," she told Sky News on Monday.

Dr Phelps said general practitioners had been absorbing increased costs of managing a practice when they bulk billed patients.

"If indexation had kept up with the cost of managing a practice and there hadn't been the rebate freeze, then the rebate would be about double what it is at the moment," she said.

The freeze was introduced by Labor's Gillard government in 2013 as a temporary measure.

It was extended by the Liberal-National coalition in 2014 to four years and extended for another two years in 2016, before the government laid out a plan in its 2017 budget to gradually wind up the measure.

The commitment comes as Labor attempts to draw voters' attention to cuts made to services when Prime Minister Scott Morrison was previously treasurer, as he tried to push through big company tax cuts.

The government has said it is delivering record funding for essential health services.