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Estimate a property gain, its current-discount income tax and the tax under the July 2027 indexation rules.
Gain
$200,000Sale price less entered cost baseCGT: current-discount baseline
$33,150Estimate with the 50% discountThe entered gain is $200,000, giving an estimated $33,150 of additional resident income tax under the current rules for 2026-27.
Switch on the comparison to estimate tax under the July 2027 rules.
The normal holding-period test is met.
Example: illustrative taxable income of $80,000.
Rates as of
The calculator subtracts your cost base from the sale price, then estimates the rise in resident income tax when the taxable part of the gain is added to your other taxable income, all for your ownership share.
The current 12-month test excludes the purchase and sale days, and both dates normally mean the contract dates.
Buy on 1 April 2020 with a $600,000 cost base and sign a sale contract on 1 October 2026 for $800,000: a $200,000 gain. The discount leaves $100,000 to add to $80,000 of other taxable income. Under the 2026-27 bands, tax on $180,000 is $47,670 and on $80,000 is $14,520, so the estimated CGT is $33,150.
Selling on 1 October 2030 for $850,000 instead, with an illustrative $760,000 market value at 30 June 2027, halves the $160,000 gain to that date. At the typical 2.5% inflation, the projected CPI factor from the September quarter 2027 to the December quarter 2030 is 1.083, so the indexed cost base is $823,080 and the later gain is $26,920. Tax on the $106,920 net capital gain is an estimated $35,710.40, against $43,600 under the 50% method: a difference of -$7,889.60.
The estimate assumes an Australian resident individual who owns the property directly, with no other capital gains or losses and no main residence exemption. It excludes the Medicare levy, surcharges, offsets, and new residential dwellings and affordable housing. Sales after 30 June 2028 use the 2027-28 rates, the latest enacted. Acquisitions before 20 September 1985 and sales before 1 July 2025 have no tax result.
Costs from 1 July 2027 that you do not list count in the cost base at 30 June 2027, or at a later purchase, with an equal reduced cost base. Capital works deductions from 1 July 2027 reduce the later cost base after indexation, preserving the indexed component under section 110-37(1). They can increase the later gain, without changing the gain to 30 June 2027. Expenditure excluded from an individual cost base element is never included and must not be entered as these reductions. A later loss uses the reduced cost base, with no indexation or listed costs of owning (section 110-55), and offsets the gain to 30 June 2027 before the discount; proceeds between the two cost bases give no later gain or loss.
Consumer Price Index (CPI) figures after the June quarter 2026 are projected from your expected inflation.
Under the Treasury Laws Amendment (Tax Reform No. 1) Act 2026, assented to on 26 June 2026, an individual’s asset held at the end of 30 June 2027 is treated as sold at market value and reacquired on 1 July 2027 (section 112-155 of the Income Tax Assessment Act 1997). That gain is deferred to the sale and keeps the 50% discount if the 12-month test is met (section 112-160).
Later gains get no discount; each cost base element except the third, costs of owning, is indexed (section 110-36(1A)) by a factor to three decimal places, not applied if 1 or less (sections 960-270 and 960-275). Indexation needs 12 months of ownership, ignoring the deemed sale (Division 114). Division 119 adds tax so these gains bear at least 30%, unless you receive a section 119-15 payment, such as the Age Pension, in that income year.
The ATO’s CGT discount guidance explains the current rules. Treasury’s August 2026 draft apportioning method is not law, so this calculator uses market value.
Seek advice before signing a sale contract if the property was ever your home, ownership or residency changed, it was inherited, you have capital losses or cost base reductions from 1 July 2027, it may be a new residential dwelling, you need a 30 June 2027 valuation, or you are unsure which costs belong in the cost base.
Start with the sale proceeds less the correctly adjusted cost base. Under current law, an eligible resident individual who held the property for at least 12 months includes half of a positive gain, or the whole gain for a shorter holding. The estimate here is the increase in resident income tax when that taxable gain is added to your other taxable income. It excludes the Medicare levy, offsets and other capital gains or losses.
In some circumstances, a former home rented out can continue to be treated as your main residence for up to six years. It is not an automatic exemption for any investment property. Eligibility depends on occupation, absence, other homes and residency. Those facts are not inputs here, so this calculator does not apply the exemption.
There is no universal exemption for an investment property. Correct cost-base records, eligible capital losses and applicable statutory exemptions can change the taxable gain, but each has conditions. This calculator assumes a fully taxable investment held by an Australian resident individual with no other capital losses. Ask a tax adviser before claiming an exemption or planning a sale.
The Treasury Laws Amendment (Tax Reform No. 1) Act 2026 replaces the 50% discount with cost base indexation for gains individuals make from 1 July 2027, and adds a 30% minimum tax on those gains. A property held at the end of 30 June 2027 is treated as sold and bought back at its market value, and the gain up to that date can keep the 50% discount when you sell. Switch on the comparison to estimate both results; future CPI is projected from your expected inflation, so the figures are estimates.
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