Prime Minister Tony Abbott has avoided putting a timetable on when his government will return the budget to surplus.
Shadow treasurer Chris Bowen reminded the prime minister that only 56 days ago he said he would bring the budget back to "broad balance" in 2017/18.
"Does the prime minister stand by this commitment," Mr Bowen asked in parliament question time on Tuesday.
Mr Abbott said the coalition made a series of fundamental commitments to the Australian people in the lead-up to the 2013 election, one of which was getting the budget back under control.
"That is exactly what we are doing," Mr Abbott said.
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"This government is absolutely ... determined to restore the budget to surplus as quickly as we reasonably can."
An analysis by Deloitte Access Economics on Monday said because of tax revenue writedowns and additional spending on national security and military operations, the 2017/18 deficit would more likely be around $12.4 billion.
That compares with the near balance of $2.8 billion deficit in 2017/18 projected in the May budget.
