The defensibility test
A tax valuation is not accepted because a valuer asserted a number. It is accepted because the report demonstrates a methodology and an evidence base another competent professional would follow to a similar conclusion.
In practice that means five things must be visible in the document: the effective date, the basis of value, the comparable sales relied on with their dates and prices, the adjustments made against each, and the signature of a registered valuer. A one-page letter with a figure on it satisfies none of them, and that is exactly the document that gets challenged on review.
Retrospective work is a discipline, not a discount
Most tax valuations look backwards — to the date a main residence became an investment, the date of death, or a legislated historical date. The correct method uses only evidence available at that date and the property's condition as it then existed.
Applying a percentage to today's value is not a valuation. It ignores the property's own condition at the time and the specific evidence of the period, and it does not withstand scrutiny. If a provider offers a retrospective figure without researching period sales, that is what they are doing.
Coordinate with your adviser first
Your accountant or auditor determines which date is required, whether the whole property or an apportioned interest is being valued, and what evidence standard applies. We determine the value at that date.
Getting that division right avoids the most wasteful outcome in this area: a technically correct valuation at the wrong effective date. Confirm the date before instructing, and where an SMSF audit is involved, confirm what your auditor will accept before the financial year closes rather than during the audit.