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But after that, the firm expects the economy to grow by 5.3 per cent in 2021-22 and then 4 per cent the following year. After big falls in 2020-21, private consumption, housing construction and private investment are also expected to lift.

The forecasts hinge on the nation's borders being reopened and the discovery of a vaccine for the virus.

Government spending will hold up the economy in the mean time, with it to grow 6.5 per cent this year after a surge of 6 per cent in 2019-20.

The budget deficit for the just completed financial year is now on track for a record $90 billion, with Deloitte expecting public debt to reach $1 trillion by 2024. Last week, it hit an all-time high of $691.3 billion.

Deloitte partner Chris Richardson said the economy would benefit from the way the coronavirus had been controlled.

"The recession may well have already past its worst," he said.

"Even so, families are struggling with the toxic trio of high debt, high unemployment and low confidence and 2020 is a shocker of a year. The ranks of the unemployed will be badly swollen for a while."

The firm expects unemployment to average 8.2 per cent in the current financial year. Even by 2024-25, Deloitte is forecasting the jobless rate to still be above its pre-virus low of 5.1 per cent.

Wage growth is tipped to lag inflation out to 2024-25, with full-time employment to grow slower than part-time jobs for several years.

Over the entire period, interest rates are not expected to move.

Mr Richardson said one of the biggest headwinds would be the lack of population growth.

The government is expecting net overseas migration to collapse by up to 85 per cent in 2020-21.

Deloitte said this would translate into 250,000 fewer people living permanently in the country, a shortfall that would affect the economy for years.

"Because we take more migrants than most, Australia's overall population growth has been high. And our population hasn't aged as fast as others either, as our migrants are relatively young," Mr Richardson said.

"But that flow of migrants has now all but turned off. That hurts tourism and education immediately, and it also weighs on recovery, affecting everything from housing construction to the utilities."