The Treasury secretary's report will form a blueprint for tax reform over the next 25 years and has been with the federal government since December.

''It will be released by the budget,'' Mr Swan said yesterday.

The review required a mature discussion about tax reform and was not ''some budget-ready set of proposals that we can pull out … and suddenly insert into a budget'', he said.

His comments reinforced the government's plan to specify whether or not it would adopt each proposal as it was announced, reducing the opposition's ability to criticise it and limiting uncertainty for business.

Meanwhile, the Deputy Opposition Leader, Julie Bishop, yesterday defended the Coalition's paid parental leave scheme against criticism from big business.

The opposition was forced to pay for the program with a tax because Labor had spent the budget surplus, she said.

Ms Bishop said a ''temporary levy'' on big businesses would help fund the plan which grants six months' paid parental leave up to $75,000. She said temporary levies had worked in the past, such as the superannuation surcharge levy scrapped in 2005.

The government's scheme would pay parents 18 weeks at the minimum wage. It is scheduled to start in January.