The Federal Government says it expects more holes will be uncovered in the Opposition's costings as a dispute continues over $400 million worth of savings announced in Tony Abbott's budget reply.

Mr Abbott announced $5 billion in savings, mostly to be spent on keeping carbon tax compensation.

The Opposition Leader said he would save up to $400 million by scrapping Labor's green loans scheme, the Clean Energy Finance Corporation (CEFC).

But Finance Minister Penny Wong says it is not a saving because the money is no longer in the budget.

She said the Government revealed last month that the scheme had to be financially self-sufficient.

"We made it very clear in the investment mandate that they would lend on a commercial basis, so there's not a budget impact," Senator Wong said.

The Opposition's figure came from a mid-year budget update 18 months ago.

Coalition finance spokesman Andrew Robb stands by the figure.

"They cannot guarantee commercial rates for loans which the banks won't touch," he said.

He says the budget variation should have been announced.

"This is totally deceitful... based on a totally spurious aspiration that these projects will provide a commercial return," he said.

Mr Robb says there is no need for the scheme if it operates on the same basis as banks.

Senior Cabinet minister Craig Emerson said this morning that the Government expected to see further holes in the Coalition's costings because they want to head into the election "cutting to the bone".

"This is what the Coalition's actual plan is - they've got form on this," he told ABC News Breakfast.

"At the last election they took policies which they said were fully audited into the election, and they had an $11 billion hole.

"And here we are just three days after the budget reply and there's already a $400 million hole and plenty more to come."

Sorry, this video has expired Craig Emerson speaks with ABC News Breakfast

Mr Abbott's official budget reply speech on Thursday night gave an insight into some of the spending cuts the Coalition would make if it wins September's election.

Billions of dollars would be slashed by delaying the increase in the compulsory superannuation contribution by two years and by scrapping supplementary payments to people on benefits.

A future Coalition government would also not follow through with the Government's proposed overhaul of school funding unless it had the unanimous support from all states and territories.

One of the Coalition's key promises is to scrap the carbon tax, a move Mr Abbott insists will help ease the strain on family budgets.

Yesterday, Prime Minister Julia Gillard joined her senior ministers in condemning Mr Abbott's plans for the nation's finances.

"These are just the start of the cuts to the bone that the Leader of the Opposition has planned," Ms Gillard said.

In return, Mr Abbott offered his opinion on the Government's performance.

"The trouble with the current Government is that it has never graduated from being an opposition to being a government," he said.