Treasury has costed three coalition policies and assessed their impact on businesses at the request of the federal government.
Coalition shadow treasurer Mr Hockey was "alarmed" that Treasury's "unsolicited" analysis was leaked to the media and on Monday wrote to department secretary Martin Parkinson demanding an explanation.
But a spokesman for Treasurer Wayne Swan on Tuesday said it was not "remotely unusual" for Treasury to analyse policies in the public domain and the same thing had occurred under previous regimes.
"It's doing its job as it did under the previous government," the spokesman said.
"From time to time governments of both persuasions publicise information to contribute to a more fulsome debate about policies."
Labor on Monday used the Treasury report to argue a coalition government would slap higher taxes on business and dismissed the opposition's anger that the "unsolicited" costing had been released without its full knowledge.
The analysis, published by Fairfax Media, showed three coalition tax policies would cost businesses $4.57 billion in the first full year of a Liberal-National government and $17.2 billion over four years.
The policies include a 1.5 per cent levy on big companies to fund paid parental leave, axing the instant asset write-off and other tax breaks for small business funded by the carbon tax and the abolition of the business loss carry-back policy.
But Mr Hockey said on Monday the figures were "grossly inaccurate", although he declined to say what treasury assumptions were wrong.
In his letter to Dr Parkinson, Mr Hockey said "if Treasury undertook to conduct these unsolicited costings, or subsequently released these costings to the media, then the apolitical and non-partisan nature of Treasury has been severely compromised".
He also asked whether Mr Swan's office had sought the costings and whether Treasury had been told the analysis would be released to the media.
Mr Swan's spokesman said Mr Hockey should take responsibility for the impact of the policies and not blame hardworking Treasury officials.
"The onus is on Joe Hockey and the Liberal Party to prove that their massive tax grab will not smash the business community," the spokesman said.
Comment is being sought from Mr Hockey.
Acting Treasurer Penny Wong urged the opposition to be more transparent about the costs of their policies.
"What's embarrassing here and what's bad for public confidence is that the people who say they're ready to run the country refuse to be upfront with the Australian people about the cost of their policies," Senator Wong told Sky News.