By Lenore Taylor
A confidential Treasury analysis has revealed an $800 million hole in the Coalition budget costings Tony Abbott has promised will add up to a bigger surplus in three years than that promised by Labor.
The Coalition's single biggest budget saving - $2.44 billion over the next four years - comes from the interest it will not have to pay when it scraps Labor's national broadband network.
But, according to the Treasury analysis dated July 5 and obtained by the Herald, the savings on interest payments would be $1.6 billion, a discrepancy of $800 million.
With the Coalition preparing to unveil a bigger budget surplus at the end of the campaign as a ''grand finale'' to its claim to be a better economic manager and the government using an economic attack against Mr Abbott to try to turn around its campaign, the battle over budget costings is expected to be fierce.
The Opposition Leader repeatedly refused yesterday to put a figure on his claimed budget surplus for 2012-13, but pledged it would be ''significantly larger'' than Labor's figure of $3.5 billion.
The shadow treasurer, Joe Hockey, promised all Coalition policies would be lodged with the Treasury for independent costing analysis by Friday, after the Treasurer, Wayne Swan, used a National Press Club debate to attack Mr Hockey for submitting just 1.5 per cent of Coalition policies to the Treasury.
In 2007 the then Labor opposition submitted most of its costings to the Treasury just 12 hours before the election. ''We will not go down the path of lodging hundreds of policies 12 hours or 24 hours before election day,'' said Mr Hockey, who is also getting an independent assessment from a private accounting firm.
''You're setting a benchmark for us that you never met yourself.''
During the debate, Mr Hockey said the ''debt reduction taskforce'' promised by Mr Abbott would focus ''on identifying … if Labor has not told us the truth about their programs'', but said no matter what the Coalition found when it came to office it would make no changes or reductions to its $8.8 billion paid parental leave scheme.
Mr Hockey said the Coalition had announced $28.58 billion in savings during the campaign, $2.8 billion more than its spending. It is also $5 billion more than the detailed savings measures the Coalition has announced.
Sources said the figure included an unannounced decision by the Coalition to adopt almost all the savings announced by Labor during the campaign, including $193 million from increased passport fees and a crackdown on tax avoidance.
Labor also questioned Mr Hockey's calculation that the Coalition had announced $25.7 billion in new spending. The Coalition says that figure includes a ''cost'', in book-keeping terms, of abolishing Labor's mining tax, and the amount of real new spending is more like $18 billion.
Last night Labor issued figures it said showed ''real'' new Coalition spending of at least $27 billion and demanded the Coalition explain this discrepancy.
Mr Hockey demanded to know how Labor would make up the $450 million shortfall between its spending and its announced savings.
The Treasury analysis of the Coalition's claimed broadband savings, completed before the election, said the saving on interest payments would be $57 million in 2010-11 (not the $177 million claimed by the Coalition); $232 million in 2011-12 (rather than $465 million); $509 million in 2012-13 (not $735 million); and $805 million in 2013-14 (not $1.04 billion).
Mr Hockey said during yesterday's debate that if the Coalition had faced the global financial crisis it would ''of course'' have engaged in stimulus spending and would ''obviously'' have presided over a budget deficit, but said the spending would have been higher quality and the deficit smaller. Mr Swan said the government had saved Australia from mass unemployment.