Tony Abbott will promise Australian companies a 1.5% tax cut from 1 July 2015, in his first major policy announcement of the election campaign.

The Coalition say the tax cut will fully offset the 1.5% “levy” he will impose on the 3,000 biggest companies to help pay for his paid parental leave scheme, leaving big business no worse off and those small businesses that are incorporated better off.

The Coalition had refused to re-commit to the 1.5% company tax reduction that was also pledged in the 2010 poll, promising only a “modest company tax cut” at a time when it could be afforded.

The $5bn cost of the tax cut over the forward estimates will play into a fierce debate over economic management that has dominated the first two days of the federal election campaign. Labor welcomed Tuesday’s interest rate cut, but the Coalition insisted it was another sign of a slowing economy.

Labor has also attacked the Coalition for refusing to make any commitments about the budget deficits or surpluses it might deliver if elected on 7 September.

The Coalition’s promised company tax cut would take the rate from 30% to 28.5%. Labor had promised a 2% tax cut to be paid for by the mining tax, but the first percentage point was dropped when the mining tax did not raise the expected revenue and the second percentage point was also abandoned in the May 2012 budget when payments to households were increased instead.

Abbott has been under pressure to pare back the cost of his expensive paid parental leave scheme, estimated at more than $4.3bn a year. But he has stuck to his signature policy despite criticism from his own party and business groups.

As outlined in the last election, it offers 26 weeks of paid leave for new mothers at their full wage, up to an income cap of $150,000 a year. Labor’s scheme offers 18 weeks’ pay at the minimum wage.

The Coalition has not said clearly when its higher parental payments would start, but has suggested they are likely to begin at the same time as the levy that helps to pay for them.

“Lowering the company tax rate is part of our plan to build a strong, prosperous economy with more investment and more jobs,” Abbott said in comments provided ahead of the announcement in Adelaide on Tuesday morning.

“From 1 July next year, the carbon tax and the mining tax will go. And from 1 July 2015 the Coalition will deliver a 1.5% company tax cut to further help Australian businesses compete, grow and create jobs.

“Labor has talked and talked about cutting the company tax rate. We will actually do it.”

Labor has criticised Abbott’s paid parental plan as a “Rolls Royce scheme” which would see business pass costs on to all Australians, including those on low incomes, in order to pay higher benefits to the rich.