Ratings agency Moody's says Australia's triple-A credit rating remains intact but has expressed doubt about the federal government's timetable for reducing the budget deficit.
Moody's said on Friday it expects that government revenues will rise more slowly than projections in Tuesday's federal budget, while spending will be higher than forecast.
The agency said it expected government debt to rise to slightly above 40 per cent of GDP within three years - from around 36 per cent in 2014/15 - but that such a debt burden "would be in line with that of other Aaa-rated sovereigns".
In his budget, Treasurer Scott Morrison forecast a deficit of $29.4 billion in 2017/18, with a surplus of $7.4 billion by 2020/21.
The budget also forecast a jump in wage growth well above recent, stagnant levels and a drop in unemployment to 5.25 per cent in 2020/21 from the current 5.9 per cent.
"Moody's points out that in this budget, like in the previous ones, the government projects a rise in revenues as a share of GDP; a trend that has not materialised in the last three years," the agency said in a note on Friday.
"By contrast, Moody's forecasts broadly stable revenues as a share of GDP.
The budget also included a multi-billion dollar infrastructure spending program, embraced by the government as part of a new focus on the acceptability of "good debt" that generates a return, versus "bad debt" incurred to fund recurrent spending on items such as social welfare and health.
Moody's said the government's ambition to restrain spending over the next four years "will likely prove challenging, because of the demands on current and investment spending".
