Finance Minister Mathias Cormann has ducked questions on whether the mid-year budget review will keep the projected return to surplus in 2021 as was predicted in May.
The government is waiting for the September quarter national accounts figures due on December 7 before finalising its budget numbers for the update on December 19.
Senator Cormann told ABC television on Sunday he wants to wait for hard information, rather than "making decisions based on a sense" of what might happen with the surplus timing.
"What we can say is, as we have done, at every single budget in every single budget update, the policy decisions of the government will seek to improve the budget bottom line," he said.
The government's latest monthly financial statement released on Friday showed the budget deficit stood at $24.5 billion in October, almost $4 billion less than had been projected after four months of the 2016/17 financial year.
The May budget had forecast a $37.1 billion deficit for the full financial year.
However, an independent report released last week predicted a $24 billion budget blow-out over the next four years, which would see the 2016/17 deficit widen to $40.5 billion.
Former prime minister Tony Abbott believes there needs to be a "big new push" on budget repair and for the government to have another look at some of the measures in his controversial 2014 budget.
"We can't go on indulging in what I used to describe as a cash splash with borrowed money," he told Sky News.
"If we don't get debt and deficit down, we won't just lose our triple-A credit rating, we'll be ripping off our children and grandchildren."
He believes if the 2014 budget had been passed more or less intact, the nation's finances would be in a very different position.
He said there needed to be a tough conversation with the Australian people, something Social Services Minister Christian Porter and Human Services Minister Alan Tudge had begun.
Opposition finance spokesman Jim Chalmers thought this was a "extraordinary intervention" by the former prime minister, reviving the GP tax and harsher pension cuts.
"We know that when he and the other right-wing knuckle-draggers in the Liberal Party yank on Malcolm Turnbull's leash, we know that the prime minister just meekly follows along," Dr Chalmers told reporters in Brisbane.
But reflecting on his period as prime minister, Mr Abbott admitted he made a mistake abolishing the debt ceiling in late 2013 and just after his government was elected.
"We didn't want a crisis of confidence before Christmas," he said.
