Capital gains tax is a significant obligation for Western Australian property owners — and WA's extraordinary market cycles make it a particularly complex one. Perth's history of boom-and-bust price movements, driven by the resources sector, means that the date at which a property's value is established for CGT purposes can make an enormous difference to the taxable gain.
At the centre of most complex WA CGT calculations is a formal property valuation — prepared by a licensed WA valuer, at a specific past or present date, with documented comparable evidence from the Landgate database. The ATO requires this, and the consequences of getting it wrong can be severe.
This guide explains how CGT applies to property in Western Australia, when a formal valuation is required, what the ATO expects, and the specific WA market considerations that make getting the date right so important.
The WA Market Context: Why CGT Valuations Matter More Here
WA's resources-driven market has produced some of Australia's most dramatic property value movements. Perth houses that were worth $300,000 in 2005 reached $600,000 or more by 2012, fell back toward $450,000 by 2017, and may now be worth $900,000 or more. Pilbara investment properties went from $200,000 to $1 million and back in less than a decade.
These extreme movements mean that the date at which a cost base is established — when a property changed from residential to investment use, when it was inherited, or when it was acquired before the CGT introduction — can shift the taxable gain by hundreds of thousands of dollars. In this environment, proper CGT valuation documentation is not a formality; it is a significant financial discipline.
When Is a Formal Valuation Required for CGT in WA?
Change of Use: Home to Rental Property
One of the most common CGT valuation situations in WA is converting a principal residence to a rental property. This happens frequently in WA for resource-sector related reasons: a homeowner takes a FIFO job in the Pilbara and rents out their Perth home; a family relocates to a mining town and leases their metropolitan property; or a buyer in a boom market decides to invest rather than sell when the market peaks.
When this happens, the market value of the property at the date of the change in use becomes the new cost base. A formal valuation from a licensed WA valuer at that date is the only defensible basis for this figure. In a volatile WA market, the difference between the actual date of change and a date a few months earlier or later can be substantial — making precision essential.
Inherited WA Property
When a Western Australian property is inherited, the CGT treatment depends on when the deceased acquired it and how it was used. For properties that were the deceased's main residence at the date of death and acquired post-CGT, beneficiaries selling within two years of death may access a full exemption. For other inherited WA properties, the market value at the date of death is the cost base — making the date-of-death valuation directly relevant to the beneficiary's future CGT liability.
Pre-CGT WA Property (Pre-September 1985)
WA properties acquired before 20 September 1985 use the market value on that date as the cost base. For a Perth suburb house that was worth $80,000 in 1985 and is now worth $1 million, establishing the 1985 value accurately is critical — it largely determines whether the gain is assessed from $80,000 or from some other figure. A formal retrospective valuation as at 20 September 1985, using historical Landgate and REIWA data from that era, is required.
Pilbara and Regional WA Property
WA's regional property markets present specific CGT challenges. Pilbara investment properties acquired during the mining boom and sold during the subsequent correction have produced capital losses — which may be able to offset other capital gains. Conversely, properties sold during the recovery have produced large gains from depression-era cost bases. In both cases, accurate formal valuations at the relevant dates are essential for correct CGT calculation. The volatility of these markets makes documentation even more critical than in metropolitan Perth.
What the ATO Expects from a WA CGT Valuation
The ATO's guidance requires that CGT valuations be prepared by a suitably qualified, independent valuer. For WA properties, this means a valuer licensed under the Land Valuers Licensing Act 1978 (WA). The report must be based on objective evidence — comparable Landgate sales from around the relevant date, documented methodology, and a clearly stated valuation date. An online estimate, an agent's appraisal, or a self-assessment is not acceptable.
The ATO has access to Landgate transfer data for all WA property transactions. CGT returns that appear inconsistent with known Landgate transaction prices, or that lack supporting valuation documentation for cost base claims, are audit triggers. A formal valuation report on file is the best protection.
Frequently Asked Questions
Can I use a real estate agent****'****s appraisal for CGT in WA?
No. The ATO requires that CGT valuations be prepared by a suitably qualified, independent professional — which means a licensed WA valuer, not a real estate agent. An agent's appraisal is a commercial service and does not carry the professional accountability of a licensed valuer's report. Using one as a CGT cost base creates audit risk and, if challenged, the ATO may substitute a less favourable value of their own.
What if I didn****'****t get a valuation when my Perth property changed from home to rental?
You may still be able to commission a retrospective valuation for the relevant past date. The further back the date, the more challenging the assignment — but a well-documented retrospective report from a licensed WA valuer is far better than no valuation. WA's market volatility makes this particularly important: in a rapidly moving market, even a few months' difference in the retrospective date can produce a meaningfully different cost base figure. Speak with your accountant about the extent of your CGT exposure and whether a retrospective valuation is necessary.
What is the CGT treatment for Pilbara investment property that has fallen in value?
If a WA investment property is sold for less than its cost base — producing a capital loss — that loss can be offset against capital gains from other assets in the same year, or carried forward to offset future capital gains. There is no CGT payable on a capital loss itself. However, the capital loss must be calculated correctly: acquisition cost plus eligible expenses, minus the disposal proceeds. If the cost base was inflated (for example, if the original purchase price reflected boom-market conditions), the capital loss may be less than expected. A licensed WA valuer can advise on the historical evidence relevant to your specific situation.