Federal budget shows 3.75pct jobless rate

The federal budget will predict that Australia's jobless rate will sink to 3.75 per cent in 2022. (AAP)

Forecasts for the unemployment rate have been slashed in the federal budget to levels not seen since the early 1970s.

Treasurer Josh Frydenberg will hand down his fourth budget on Tuesday predicting an unemployment rate falling to 3.75 per cent later this year, the lowest level since August 1974.