Labor will deliver its answer to the Government's "jobs and growth" election pitch today, using its campaign launch to announce a policy that provides a tax break for small businesses hiring new staff.

Key points: Businesses will get a $20,000 incentive to hire mums returning to work, older job seekers, under 25s

Businesses will get a $20,000 incentive to hire mums returning to work, older job seekers, under 25s The policy is designed to create 30,000 new jobs

The policy is designed to create 30,000 new jobs Labor says it will commit $400m to build Sydney's rail link

Businesses will get a $20,000 incentive to hire a mum returning to work, an older job seeker or someone under 25.

The scheme is also likely to be available to people who have taken time off work to care for a relative.

The policy is worth $257 million and designed to create 30,000 new jobs each year.

The Government has made a small business tax cut a major plank of its election platform, it has also promised to gradually extend the definition of a small business from a turnover of $2 million to $10 million.

Labor will also announce that it will back three major infrastructure projects in Brisbane, Sydney and Melbourne if it wins power.

It will commit $400 million towards building the rail link connecting Sydney's outer suburbs in the north west and south west, by the second Sydney airport.

Labor said that would allow the rail line to be built at the same time as the second airport is developed.

The Melbourne Metro Tunnel project will get $500 million, along with extra car parking at stations and bicycle facilities.

The party said it would put $800 million toward the Cross River Rail project in Brisbane — as long as its business case adds up and it successfully finalises negotiations with the State Government.

Labor's warning on Coalition privatisation plans

Labor Leader Bill Shorten will use a study of "reform" options within the Department of Human Services to warn the Government is still planning to privatise Medicare, despite the Prime Minister Malcolm Turnbull emphatically denying the accusations.

Mr Shorten said the document showed the Prime Minister had a "secret plan" to privatise services within Medicare and beyond.

"This shows that Malcolm Turnbull's plan to privatise Medicare is just the beginning," he said.

"This is the Liberals' hand-crafted blueprint for the privatisation of services, including Medicare."

Mr Turnbull has rejected Labor's advertising campaign that privatisation is on the cards, and yesterday went even further declaring "every element" of Medicare would remain in Government hands.

That is despite earlier consideration of privatising a string of Government payments.

The opposition has seized on a Productivity Commission issues paper focused on the Department of Human Services which was released earlier this month.

Labor is highlighting the terms of reference, specified by the Treasurer Scott Morrison in April, which state the inquiry will consider "private sector providers and overseas examples like the United States".

Further, it says the final report will set out findings from case studies and international experiences to identify which services within the "human services sector" are best suited to competition.

The preliminary and final reports from the study will not be released until after the election.