Investors are prematurely offloading their properties before tax changes even hit the market, resulting in a listings boom but fewer rentals.
Rental listings across the country have shown large annual falls, with the steepest downturn so far in May.
All capital cities were part of the trend, with Hobart losing just 0.3 per cent of listing volume, but Darwin was down 2.1 per cent and Melbourne 1.7 per cent.
Sydney was hit hardest in the past year, down 1.5 per cent in May and 9.8 per cent annually, data from Neoval shows.
The figures suggested some of the nation's more vulnerable people were at risk of not finding affordable homes, Ray White chief economist Nerida Conisbee said.
"A home listed for sale does not help someone looking for a lease. Rental availability is what determines how much choice renters have," she said.
