A Productivity Commission report examining housing and homelessness found nearly half of all people receiving commonwealth rent assistance were spending more than 30 per cent of their income on rent, the common measurement of housing stress.

Coming in at 45.7 per cent for 2021, that figure was at 40.5 per cent in 2019 and 29.5 per cent in 2020, when a COVID supplement payment was in place.

The report also shows nearly a third of assistance-receiving households with a person aged more than 75 were in housing stress.

It also found social housing supply is not keeping up with Australia's growing population, with supply growing by 4.5 per cent since 2012 compared with population growth of 13.2 per cent.

Everybody's Home national spokesperson Kate Colvin said affordable home supply was "rapidly vanishing" for low and modest income earners.

"The Australian rental market now resembles a great white shark, swallowing family incomes almost whole. It's simply astounding that even after receiving rent assistance, almost half of households are still in housing stress," she said.

"COVID has completely warped our housing market. The benefits are being funnelled to those who already own housing while people in the rental market are forced into a brutal contest for survival."

Ms Colvin said the CRA program needs "a serious adjustment" to address the crisis facing the nation.

"The best way to address this is to lift the historically low rates of social housing investment," she said.

"We need at least 25,000 new social housing units built per year just to begin closing the widening housing gap."

Australian Associated Press