Australia's housing downturn is spreading across the country, with the latest property price data showing previously resilient markets that had recently set record-high prices are now experiencing a decline in values.

New Zealand's housing market is going through the longest and deepest downturn in 30 or 40 years, property data firm Cotality says.

Property values have racked up their biggest fall since Anthony Albanese took office as rates, cost of living and tax changes collide.