The treasurer has pledged he won't even consider repairing the budget before the jobless rate gets below five per cent, which according to Treasury's forecasts won't happen until the 2022/23 financial year.

"There is no economic recovery without a jobs recovery, and there is no budget recovery without a jobs recovery," Mr Frydenberg told the National Press Club in his traditional post-budget speech.

"We must keep our momentum going and we cannot afford to be complacent."

The budget more or less spends the benefits of the economic rebound so far, based on an unexpected drop in the unemployment rate and the huge spike in the iron ore price bolstering revenues.

Billions of dollars will be spent on aged care, infrastructure, the NDIS and employment incentives such as additional childcare funding, as well as tax breaks for low and middle income earners and small business.

The treasurer's third budget is still forecasting sizeable budget deficits over the next few years and a surplus is not projected in at least the next decade.

Asked on ABC radio whether he would still be in the parliament when the budget is back in surplus, Mr Frydenberg replied: "I'm not going anywhere."

"But I can tell you that my number one goal has to prevent a generation of Australians going into long-term unemployment."

AMP Capital chief economist Shane Oliver said it makes sense for the government to remain focused on growing the economy.

"Reverting quickly to fiscal austerity would just put all the pressure back on the RBA at a time when it has few levers to pull and delay the return to full employment and decent wages growth," he said.

Treasury estimates the budget initiatives will create 250,000 jobs.

But shadow treasurer Jim Chalmers says the government spent $100 billion in the budget and has racked up $1 trillion in debt.

"I don't think they've got a lot to show for it," he told Sydney's 2GB radio.

"You'd think ... we'd have a much stronger economy at the end of it, but their own budget papers say that even after the four year budget period, real wages will have actually gone backwards."

The budget sugar-hit lifts economic growth to a speedy 4.25 per cent in the 2021/22 financial year, but then it slows to around 2.5 per cent thereafter, and below what is seen as the long-term trend of about 2.8 per cent.

Wages growth ticks up to 1.5 per cent in 2021/22 - lower than inflation at 1.75 per cent - and then runs line-ball for the following two years.

"I think that's an admission of failure," Dr Chalmers said.

Wage growth is predicted to be only slightly over inflation in 2024/25 - 2.75 per cent compared with 2.5 per cent.

Economists don't agree with all of Treasury's predictions, particularly when it comes to iron ore.

Treasury is sticking with its $US55 per tonne forecast for iron ore - albeit being realised next year rather than this one - even though the red metal recently struck a record high of around $US230 per tonne.

"Not many forecasters would agree with that," Westpac chief economist Bill Evans said.

"This upside risk in the iron ore price represents a potentially significant budget windfall."

Global rating agencies have maintained Australia's top-tier AAA credit rating, but some still see the risk of a reduction due to the uncertainties around the pandemic and its impact on the budget.

Australian Associated Press