The Abbott Government cannot say where almost $30 billion in budget cuts to schools will be found, says Australian Greens spokesperson for schools Senator Penny Wright.

Senator Wright said estimates questioning late last night revealed the Government had picked a random number with no thought to the consequences.

"The best Treasury could do was say the cuts to schools would be 'something less than $30 billion'," Senator Wright said.

"When even Treasury doesn't know the real numbers - you know there's no plan behind this policy.

Australian Greens Leader Christine Milne says the Prime Minister's chief business adviser, Maurice Newman, must be deaf if he hasn't heard the Greens clearly identify revenue alternatives for balancing the budget.

"Keep the carbon price, keep and fix the mining tax and get rid of fossil fuel subsidies for big polluters," said Senator Milne.

"The Greens won't allow Tony Abbott's brutal budget cuts to impact on Australians who need our support, when there are such obvious revenue alternatives.

While the Liberals have printed a booklet bemoaning a phoney budget emergency, the Australian Greens have a costed policy to avoid harsh budget cuts.

New analysis from the Parliamentary Budget Office using updated commodity data shows $35 billion could be raised by restoring the mining tax to its original intent and taxing mining super-profits.

"This opportunity to get a fair share from the big mining corporations makes a joke of Tony Abbott's attempt to justify harsh budget cuts," said Australian Greens Leader Christine Milne.

Australian Greens Leader Christine Milne called on the Labor party and cross benchers to reject any proposal from the Abbott Government for a new tax on Australians, while polluters and big business continue to be let off the hook.

"The Australian Greens will oppose any attempt to institute a new tax that will hurt Australians while the Abbott Government refuses to raise revenue from those who can afford it most.

"A tax like this on everyone except the richest and dirtiest must be rejected.

"We call on other Senators to do the same.

The Senate Inquiry into the Abbott government's Commission of Audit has today tabled a new interim report, which covers evidence presented on the effects of predicted budget cuts in the areas of health, social services and employment.

"The evidence received by the Committee directly contradicts the Government's line on the economy," said Senator Richard Di Natale, chair of the Senate Select Committee conducting the inquiry.

The Australian Greens have responded with anger to Minister Kevin Andrews comments that he will implement a disability crackdown.

"Yesterday it's the old age pension, today it's the disability support pension that is being clamped down on by the Government," said Senator Siewert, Australian Greens Spokesperson on disabilities.

"Minister Andrews is determined to make things worse for our most vulnerable community members with his reassessment schemes and his two tiered system.

The Australian Greens say Tony Abbott must come clean about his cruel cuts before voters go to the polls in elections around the country.

"How can we trust a Prime Minister who deliberately withholds information before an election?" asked Australian Greens Leader Christine Milne.

"Tony Abbott is deliberately hiding his true agenda for cruel cuts. He is being mean, tricky and secretive.

"It's completely obvious the PM is holding out until after the upcoming elections in an attempt to pull the wool over voters' eyes.