Does Treasury’s free formula cost you, or save you? Pick where and what you bought and when. The calculator fills in the ABS median for that market, projects its value to 1 July 2027, and works the tax both ways: a market valuation on the day, and Treasury's apportioning formula, which assumes the property compounded at one steady daily rate from the day you bought it to the day you sell. Every figure is editable.
| Market | Bought for | Worth 1 Jul 2027 | Formula assumes | Growth to reset | Difference in tax |
|---|
Formula costs more tax Formula saves tax Bars are scaled to the largest difference in the table.
Residential $297, commercial $594, AUD inc. GST. Turnaround 24 to 48 hours.
Capital gains tax is not a separate tax. The net gain goes into your taxable income for the year you sell and is taxed at income tax rates, with the 2% Medicare levy on top, which is why the totals above are the tax on the gain rather than a separate CGT figure. Gains before 1 July 2027 keep the 50% discount. Half the gain is added to your taxable income for the year you sell and taxed at the resident rates that apply from 1 July 2027 (nil to $18,200, then 14%, 30%, 37% and 45%) plus the 2% Medicare levy, so a larger gain is taxed at a higher rate. Gains after the reset are taxed on a cost base indexed at CPI, at the rate reached once the gain sits on top of your income, or 30%, whichever is higher. With a valuation, the 1 July 2027 value is the one you enter. With the formula, Treasury divides your sale price by the purchase price, turns that into a single daily growth rate compounded over every day you owned the asset, and applies it to the days up to the reset. Because it compounds, it loads growth into the later years, so the deemed value usually lands below a straight line and below a real valuation. Treasury released the exposure draft of the legislative instrument on 3 August 2026 and consultation closed on 21 August 2026, so the method can still change. The deemed disposal happens at the end of 30 June 2027, the same instant as the start of 1 July 2027. The choice between methods is made at lodgement for the year of sale.
Australian Bureau of Statistics, Total Value of Dwellings, Table 2: unstratified median prices of established house and attached dwelling transfers by capital city and rest of state, March quarter 2026 release, CC BY 4.0. Purchase prices are the average of the four quarters to September of the year bought. The 1 July 2027 value is the latest four-quarter average rolled forward five quarters at that market’s trailing twelve-month growth, capped at 30% a year. The Australia row is the transfer-weighted average of the fifteen regional medians.
A modelled scenario for a median property, not a calculation for yours. No purchase or selling costs, improvements or depreciation. Treasury's growth rate uses only the first element of the cost base, the purchase price, so improvements are left out of it. The 2% Medicare levy is applied flat, with no low income reduction or exemption. A loss after the reset shows as nil tax, not netted against the gain before it. Not tax advice.
From 1 July 2027 the cost base of an existing asset resets to its market value on that date. Gains built up before the reset keep their existing treatment. Gains after it fall under the new rules: the 50% discount goes, the cost base grows with CPI indexation, and the tax is your marginal rate or 30%, whichever is higher.
You can establish that 1 July 2027 value two ways. A market valuation as at the date, or Treasury's apportioning formula. The formula divides your eventual sale price by the purchase price, turns that into a single daily growth rate, and compounds it over every day you owned the asset up to the reset. Because compounding loads growth into the later years, the deemed value usually lands below what the property was really worth on the day, and more of your gain falls into the post-reset period where the discount no longer applies. That difference is what this calculator prices.
The choice is made at lodgement for the year you sell. A valuation as at 1 July 2027 is what keeps both options open, because the formula is always still available to you, while a valuation obtained years after the date is not.
Only if the formula would cost you more than the valuation does. That depends on how your property performed against one steady compounding growth rate, which is what the calculator above prices for your market and purchase year. Obtaining one keeps the choice open; skipping it means reconstructing the value later, which is harder and costs more.
The extra tax you pay by taking the free apportioning formula instead of a market valuation. It is the cost of a method that assumes one steady compounding growth rate when your property did not grow that way. The calculator above prices it for your market and purchase year.
Yes, though less often than it might seem. Compounding pushes growth towards the end of the ownership period, so the deemed value usually lands below the real one. The formula wins where a property was flat or falling before the reset and then ran hard afterwards, and where the purchase price was high relative to the eventual sale price. On the modelling above, that is the pattern for the slowest markets.
At lodgement for the year of sale, not in 2027. The practical deadline is on the valuation, not the decision: a market value as at 1 July 2027 has to be established on evidence available for that date.
The Treasury Laws Amendment (Tax Reform No. 1) Bill 2026 was introduced on 28 May 2026 and makes market value the default. Treasury released the exposure draft of the legislative instrument setting out the apportioning method on 3 August 2026, and consultation closed on 21 August 2026. The nine-step method modelled here follows that exposure draft, which can still change before it is registered.
No. They are modelled on ABS median prices for each market, not a calculation for your property, and they exclude purchase and selling costs, improvements and depreciation. Use them to see whether a valuation is worth obtaining, then get advice on your own numbers.
Yes. From 1 July 2027 the 50% CGT discount is replaced by CPI indexation of the cost base for individuals, trusts and partnerships. The calculator indexes the 1 July 2027 value at the CPI rate in the assumptions panel, which you can change, and applies it the same way to the valuation case and the formula case. The only thing that differs between the two is the 1 July 2027 value itself.
Yes, and not in the direction most people expect. Treasury works out the growth rate from the first element of the cost base, the purchase price, and nothing else. Money spent on improvements cuts your gain but is left out of that rate, so a property bought cheaply and renovated is treated as though it grew far faster than an already finished one bought for the same total outlay. The higher your original purchase price relative to the sale price, the better the formula treats you. Put your improvement spend into the assumptions panel above to see it.
Real property, and assets with no readily ascertainable market value whose cost base is not itself worked out by reference to market value. Listed shares and exchange traded funds do not use it; they take their market value on the day, which is published.
No. It models one decision: whether a market valuation or Treasury's formula gives the lower tax under the new rules for a property held across 1 July 2027 and sold afterwards. A sale before 1 July 2027 is taxed under the existing rules and is not modelled here.
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