Treasurer Jim Chalmers has launched a political broadside against the coalition, accusing it of planning a half-trillion-dollar hit to the budget bottom line.
Labor has found itself under increasing pressure in recent weeks over its decision to wind back tax concessions for investments in property, shares and trusts.
But costings released by Dr Chalmers show repealing the changes - as the coalition has promised - would cost the federal budget tens of billions of dollars in lost revenue.
The opposition's policies would cost a total of $544.4 billion over the next nine years, according to the analysis.
That includes $212 billion in lost revenue from indexing income taxes, $43.1 billion from repealing the CGT and negative gearing reforms, $44.2 billion from scrapping the new tax on trusts, $93.5 billion on increased defence spending and $50 billion from slashing Australia's migrant intake.
While the coalition would make some savings from scrapping various measures, including a tax discount on electric vehicles and a key housing fund, the government's figures suggest it would not come close to offsetting the extra spending.
"This is a multibillion-dollar debt bomb that the coalition would drop on future generations of Australians," Dr Chalmers said in a statement.
"Their uncosted policies would deliver much bigger deficits, higher debt and higher inflation."
Some of the figures Labor has relied on for its costings date back to commitments made in 2022. The government says this makes its estimates somewhat conservative.
Shadow treasurer Tim Wilson rejected the government's claims, accusing it of planning to slug Australians with billions of dollars in higher taxes.
"Jim Chalmers and Anthony Albanese have admitted they’re hitting us with $273 billion in taxes Australians didn’t vote for," he said.
Mr Wilson's figure is based on Labor refusing to back the coalition's plan to index income tax brackets in line with inflation, as well as the government's planned changes to negative gearing and the capital gains tax.
Parliament resumes on Tuesday for three sitting days, with debate over the tax reforms likely to take centre stage as the government seeks to have the legislation passed before the lengthy winter break.
The coalition is threatening to withhold support for separate legislation tightening eligibility for the National Disability Insurance Scheme if Labor tries to pass its tax changes with the support of the Greens, paving the way for messy negotiations in the coming days.
