When you need one
The common triggers are all moments where the tax law needs a value but no arm's-length sale price exists.
Main residence becomes an investment
When you move out and rent the property, its market value at that date can become the cost base for future capital gains purposes.
Investment becomes a main residence
The reverse change of use also fixes a value at the date of change.
Inherited property
A deceased estate generally requires the market value at the date of death, which may be years before the eventual sale.
Related-party transfers
Transfers between family members, into trusts or into an SMSF require market value, because the stated consideration is not evidence of it.
Pre-CGT and 1985 cost base issues
Some holdings need a value at a legislated historical date to establish a cost base.
Partial use claims
Where part of a property was used to produce income, an apportionment needs a defensible underlying value.
How a retrospective valuation works
A retrospective valuation assesses market value as at a past effective date. The method is the same as a current valuation with one critical discipline: the valuer must use only evidence that was available at that date, and must exclude everything that happened afterwards.
In practice that means analysing sales that settled around the effective date, market commentary and indices from that period, and the property's condition as it existed then. If you renovated in 2022 and the effective date is 2019, the renovation is disregarded. If the market rose 30 per cent after the effective date, that rise is irrelevant.
This is where retrospective work goes wrong most often. Applying a percentage discount to today's value is not a valuation — it is an index adjustment, and it does not withstand ATO review because it ignores the property's own condition and the specific evidence of the period.
What makes a CGT valuation defensible
The ATO does not accept a figure because a valuer asserted it. It accepts a figure because the report demonstrates a methodology and evidence base that a competent professional would reach the same way.
A defensible report names the effective date explicitly, states the basis of value, lists the comparable sales relied on with their dates and prices, shows the adjustments made against each, explains the method chosen and why, and is signed by a valuer registered under the Valuers Registration Act 1992 (Qld). A one-page letter with a number on it satisfies none of that.
Agent appraisals and online estimates
An agent's appraisal is not a valuation and is generally not accepted for capital gains purposes. Neither is an automated online estimate. Both are marketing products, and neither carries a registered valuer's professional liability.
The practical risk of using one is not immediate rejection — it is an amended assessment years later, with interest and possibly penalties, when the figure cannot be substantiated. The cost of a proper valuation is small against that exposure.
Working with your accountant
Your accountant determines what date is required and what the valuation will be used for; we determine the value at that date. That division matters, because the wrong effective date produces a technically correct valuation that is useless for the return.
Before instructing us, confirm with your accountant the exact effective date, whether the valuation should be of the whole property or an apportioned interest, and whether any improvements are to be valued separately. We will then scope the report to match.