Shadow treasurer Joe Hockey will unveil the Coalition's election costings on Thursday, leaving voters just hours to digest the numbers, while also refusing to say when the budget would be back in the black under his management.

Fairfax Media has been advised the Coalition's figures will not constitute an alternative budget, nor seek to match or exceed the government's proposed path to surplus in four years. Rather, they will show the final aggregate cost of Coalition election promises and attendant savings, even though many of those are reliant on a promise to scrap the carbon and mining tax packages and so are subject to passage through a hostile Senate.

Joe Hockey: Set to unveil the Coalition's election costings on Thursday. Credit:AFP

After five weeks of campaigning and a sustained political argument over the impact of the Coalition's spending and savings plans, Mr Hockey will reveal his list of policy costings on the penultimate day of campaigning, promising only that the budget would be ''in excess of $6 billion'' better off in cash terms under his stewardship. And he will argue that gross debt will be $16 billion lower in that time.

He will tell voters the $6 billion improvement comes from savings and from higher economic growth but does not include any expected growth dividend from dumping the carbon tax, despite Parliamentary Budget Office modelling predicting it would add $1.1 billion to the bottom line through increased economic activity.