Shadow treasurer Joe Hockey says a coalition government won't make "heroic promises" about when the budget will be returned to surplus.
Mr Hockey faced off against Treasurer Chris Bowen in a pre-election debate on the economy at the National Press Club in Canberra on Wednesday.
He said one of the problems with Labor over the past six years was that it had not "pressure tested" the economic assumptions and forecasts provided by Treasury.
Each time Labor said it would deliver a surplus, the budget outcomes showed deficits.
"If Treasury comes to me with a range of assumptions I will test them," Mr Hockey said.
"I just won't accept them because they are coming out of an organisation."
Mr Hockey said the latest key piece of Treasury work - the pre-election fiscal and economic outlook released 10 days into the election campaign - showed there were many downside risks to the budget.
"From my perspective I want to make sure we know what the worst-case scenario is so we can prepare for a rainy day, rather than budget and spend on the expectation of the best-case scenario, which is a reflection of everything Labor has done for six years," Mr Hockey said.
But Mr Bowen said it was an "insult" to Treasury not to respect its expertise.
"You work with your professional advisers ... and you accept the advice," Mr Bowen said.
The treasurer said Labor would deliver its promised $4 billion surplus in 2016/17.
"It's right that we return to surplus over time - not tomorrow because it would a hammer blow to the economy," he said.
Mr Bowen said the coalition was not being upfront about when it could deliver a surplus.
But Mr Hockey said Mr Bowen had his "L-plates on" and would never deliver a surplus.
"We will get to surplus when it is reasonable and responsible to do so," he said.
"I'm not going to make the mistake that Labor made of making big heroic promises and never delivering."
Mr Bowen said Mr Hockey's response was "a lot of huff, a lot of puff, a lot of bluster, a lot of blowing but no date".
Mr Bowen said the national economy was 14 per cent bigger than when Labor came to office in 2007.
"We're seeking another term to finish the job," he said.
He rejected Mr Hockey's argument Australia was facing a budget crisis, and high and unmanageable levels of debt.
Mr Hockey said Australia needed a change of government to build a prosperous economy.
