The cost base is everything in a capital gains tax calculation. If it’s wrong you run the risk of paying more than you should. A retrospective valuation is how you establish market value at a specific date in the past and it needs to hold up under ATO scrutiny, not just look plausible.
What the ATO Actually Requires
Market value for CGT purposes isn’t a number you arrive at by feel. The ATO requires an objective, evidence-based assessment of what a willing buyer would have paid a willing seller at the relevant date. That means comparable market sales from that period, documented methodology, and an independent qualified valuer producing the report.
An online estimate won’t cut it. Neither will a real estate agent’s recollection of what the market was doing.
The Situations That Create the Need
A retrospective valuation isn’t something you commission out of general caution. There are specific events that make one necessary.
Converting your home to a rental. The day your principal place of residence becomes an income-producing property, you need a market value figure for that date. That value becomes your new cost base. If you didn’t get a valuation at the time, you need a retrospective one now.
Moving overseas. Departing Australia can trigger a CGT event on assets that were previously exempt. The market value at the relevant date becomes critical to the calculation.
Transferring property within a family. Family transfers are not exempt from CGT by virtue of being between relatives. Market value at the date of transfer is required, and the ATO will look closely at whether the figure is supportable.
Deceased estates. Where a property passes through an estate, the cost base is typically market value at the date of death. Executors and beneficiaries need a defensible figure; one that can withstand challenge from the ATO or from other parties to the estate.
What Makes a Retrospective Valuation Defensible
The ATO challenges valuations that are poorly supported or that appear to serve the taxpayer’s preferred outcome. A report that holds up will name the effective date clearly, reference verifiable sales evidence from that period, explain the methodology, and come from a qualified, independent valuer with no interest in the result.
The further back the effective date, the harder it becomes to locate comparable sales data and establish the property’s condition at the time. That’s not a reason to avoid commissioning one – it’s a reason to move quickly once you know you need it.
Contemporaneous evidence strengthens the report. Old photographs, council records, prior appraisals, and rental histories all help the valuer reconstruct the market as it was. If you have any of that material, keep it.
What a Weak Valuation Costs You
A challenged cost base means a higher assessed gain. That means more tax than you legally owe, or a dispute with the ATO that costs time and money to resolve – usually both.
The valuation fee is not the expensive part of getting this wrong.
If you’ve converted a property, moved overseas, transferred within the family, or are working through an estate, Vanguard Valuations prepares retrospective CGT valuations across NSW, ACT, VIC, and QLD. Get in touch if you need a report your accountant can rely on.
