More than two million Australian investment properties could require a property-specific valuation as owners prepare for capital gains tax changes taking effect from 1 July 2027, according to property valuation firm Opteon, which estimates around 2.5 million residential, commercial, and agribusiness properties are potentially affected.
The changes stem from this year's federal budget, which will replace the 50% CGT discount with cost-base indexation and a 30% minimum tax on net capital gains from 1 July 2027, while also restricting negative gearing to newly built properties.
The changes make a property's value at the transition point central to future CGT outcomes, and Scott Chapman, Opteon managing director Australia and New Zealand, said owners should start understanding their position now.
"The ATO method applies a standard formula across the period you've owned the property, but property values don't grow evenly year to year," Chapman said, warning that properties which saw most of their growth before July 2027 could be taxed more heavily under the standard formula than under an independent valuation.
In one modelled scenario, a Hawthorn property owner was estimated to save more than $22,000 in capital gains tax by obtaining an independent valuation rather than relying on the proposed ATO apportionment method.
Other valuation firms have flagged similarly high stakes — JLL has estimated the gap between a professional valuation and the ATO's default formula could cost some investors as much as $58,000.
That risk is compounded by how unevenly Australian property has performed.
Opteon's July 2026 Property Pulse Check found Melbourne dwelling values fell 2.6% over the June quarter, while Perth values rose 23.9% over the past year, even as listings there increased and activity moderated. Adelaide recorded no growth in June after a strong run, and Sydney's metro market weakened through the quarter while regional NSW continued to outperform on affordability.
"Some markets have already experienced very strong growth, while others are now flat or falling," Chapman said, noting that a standard apportionment formula may not reflect when a given property actually gained most of its value.
The link between the tax changes and investor behaviour is already visible on the ground.
In the ACT, Opteon's state director reported that CGT-related tax changes weighed on investor demand and confidence from May, contributing to a broader softening in the Canberra market.
In South Australia, the slowdown in Adelaide's market has similarly been linked in part to CGT-related policy changes, which have prompted a number of investors to exit the market altogether.
In South East Queensland, buyers have grown more cautious amid federal policy changes affecting investors, with agents reporting a noticeable pullback in enquiry from first-home buyers and investors at the entry level in particular.
Opteon has already recorded a 30% jump in valuation enquiries in July, alongside softer investor demand for established residential property in several metropolitan markets.
Chapman said any sustained fall in investor participation could add further pressure to already-tight rental markets, particularly where housing supply is constrained, though he noted rents would ultimately depend on local supply, vacancy rates, and tenant affordability.
With just under a year until the changes commence, Chapman said investors don't need to rush, but should use the time to understand what their property is worth and gather the evidence they may need.
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