Treasurer Jim Chalmers has confirmed the cost of the stage three tax cuts has blown out to more than a quarter of a trillion dollars as the government looks to rein in spending in the federal budget.

New estimates have shown the tax cuts would cost $254 billion over 10 years.

Previous forecasts by the budget office had forecast the measure would cost $243.5 billion over the decade.

The government had come under pressure to scrap the stage three tax cuts but Labor had promised at the election to keep them.

Dr Chalmers said there would not be a new item in the federal budget when it is handed down on Tuesday on the tax cuts, indicating the cuts had already been legislated.

The Greens said the discovery that the tax changes would cost an extra $11 billion should be the nail in the policy’s coffin.

“Next week’s budget will be a statement of this government’s priorities. It is still not too late to scrap the stage three tax cuts and invest in genuine, immediate cost of living relief,” Greens senator Nick McKim said.

ACT independent senator David Pocock has also called for the stage three tax cuts to be ditched, but the opposition says scrapping the cuts will constitute a broken election promise.

Shadow treasurer Angus Taylor said the upgraded stage three tax cuts costings were a product of people paying more tax.

“It proves the impacts of bracket creep are very real and are hitting Australian households to the tune of billions of dollars.”

He said the easiest way to combat bracket creep was to eliminate a tax bracket.

Mr Taylor also called on the government to stick with the coalition’s tax-to-GDP ratio cap of 23.9 per cent, noting that the cap had attracted the support of the Business Council of Australia.

On Thursday, the business group called for “fiscal guardrails” to bring debt under control, including capping spending growth at two per cent annually and a tax-to-GDP cap of 23.9 per cent.

The treasurer has previously dismissed tax-to-GDP ratios as arbitrary.

Dr Chalmers also confirmed the budget would include an extra $6.4 billion on measures that were previously unfunded but still were needed, such as health and COVID-related programs.

He said the additional spending was a result of the previous government “booby-trapping” the budget with unavoidable spending.

But Mr Dutton said Labor backed the coalition’s COVID-19 response measures when in opposition.

“Labor supported every dollar of that and they promised, and they advocated at the time for another $80 billion of spending,” Mr Dutton told Sydney radio 2GB.

He expects to see spending front-loaded in the budget so that the Albanese government can tell Australians about the “terrible” debt left to them by the coalition government.

“But in the last nine years, we have taken decisions to keep the economy strong – without COVID we would have gone back into surplus,” Mr Dutton said.

– AAP