Australian CGT reform calculator

Model the impact of Australia's 2026-27 Budget capital gains tax (CGT) reform — replacing the 50% discount for individuals with cost-base indexation and a 30% minimum tax rate from 1 July 2027.

Asset details

Purchase price

Sale price

Incidental costs

Purchase and sale costs and other expenses eligible to be deducted from the cost base

Date purchased

Date sold

Property: Eligible new residential build

Tax details

Other taxable income

Include Medicare levy

The Medicare levy adds 2% to your marginal tax rate

Inflation assumption

Avg inflation over holding period

8% max inflation rate

Estimated tax payable

$31,880

Net gain after tax: $118,120

Transitional · split pre/post 1 Jul 2027


Nominal gain	$150,000
Estimated tax payable	$31,880
Effective CGT rate	21.3%
Net gain after tax	$118,120
Difference under new regime*	+$2,630 (+9.0%)
CGT regime	Transitional · split pre/post 1 Jul 2027

*when compared to current rules

Transitional calculation

This asset was purchased before 1 July 2027 and sold after 1 July 2027, so the gain is split. The split uses time-based apportionment of capital gains - this may differ from a formal 1 July 2027 Valuation. Gains before 1 July 2027 use the 50% discount. Gains after 1 July 2027 use indexation and the 30% minimum tax rate.

Pre-1 July 2027

Time held	7.00 yrs
Apportioned gain	$104,984
After 50% discount	$52,492
Tax on this portion	$20,472

Post-1 July 2027

Time held	3.00 yrs
Deemed value at 1 Jul 2027	$204,984
Indexed cost base	$220,749
Real gain	$29,251
Tax on this portion	$11,408

Total tax payable:

$31,880

Effective rate: 21.3%

Marginal tax rate exceeds 30% minimum tax rate

Rule calculation comparison

Compare what the tax would have been paid under the old regime (50% CGT discount) to the new regime (indexation with a 30% minimum tax rate). These calculations assume each rule is applied to the entire capital gain and do not factor in the actual rule or combination of rules applicable for the selected dates.

Current rules

Total tax payable:

$29,250

Effective CGT rate: 19.5%

New rules · from 1 Jul 2027

Total tax payable:

$47,578

Effective CGT rate: 31.7%

Show breakdown

Nominal gain	$150,000
Taxable amount	$75,000
Marginal rate	39.0%

50% discount applied as investment held over 12mo

Cost base	$100,000
Indexed (× 1.280)	$128,004
Real gain	$121,996
Marginal rate	39.0%*

*30% minimum tax rate not applied

Inflation sensitivity

Higher inflation reduces your taxable gain under the new rules. This table shows how your estimated tax changes across different inflation scenarios.

Inflation p.a.	Current rules	Transitional	Difference
1.00%	$29,250	$35,605	+$6,355
2.00%	$29,250	$33,134	+$3,884
2.50%	$29,250	$31,880	+$2,630
3.00%	$29,250	$30,614	+$1,364
4.00%	$29,250	$28,044	-$1,206
5.00%	$29,250	$25,424	-$3,826
6.00%	$29,250	$22,754	-$6,496
7.00%	$29,250	$20,472	-$8,778
8.00%	$29,250	$20,472	-$8,778

This calculator implements the Budget 2026-27 announcement (12 May 2026) for individuals, trusts and partnerships. Primary residence (PPOR) remains exempt; super funds are unaffected. The model assumes gains accrue evenly over the holding period for the transitional calculation (the ATO apportionment method); a 1 July 2027 valuation may produce a different result. The 30% minimum tax only applies to the post-1 July 2027 portion of the gain. Indexation here uses a compounded assumed inflation rate as a proxy for the actual CPI series (mathematically equivalent if inflation runs at the chosen rate). Tax rates use 2025-26 brackets including the 2% Medicare levy. This is a model, not tax advice — consult a registered tax adviser before acting.

Incidental costs

Any additional cost incurred as part of buying or holding the asset, such as brokerage fees, spreads or taxes.

Cost base indexation

From 1 July 2027, indexation increases your asset's original purchase price (cost base) in line with the Consumer Price Index (CPI) before the taxable gain is calculated. This replaces the 50% CGT discount, working alongside the 30% minimum tax floor, so tax applies only to the real gain above inflation.

Transitional calculation

If you bought an asset before 1 July 2027 and sell it after that date, the gain is split based on the asset's deemed value at 1 July 2027. The 50% discount applies to the pre-1 July 2027 portion; indexation and the 30% floor apply to the post-1 July 2027 portion.

Nominal gain

The full gain before any inflation adjustment - sale price minus purchase price and incidental costs.

Real gain

The capital gain that remains after indexation adjusts the cost base for inflation. This is the amount taxed under the post-1 July 2027 rules.

30% minimum tax floor

Under the new rules, you pay tax on real capital gains at your marginal income tax rate or 30%, whichever is higher. The floor applies if your marginal rate sits below 30%.

Eligible new residential build

A new residential build qualifying for the budget's concession on new builds. For these assets, you can choose between the current 50% discount rules and the new indexation method.

Calculate your capital gains tax with Sharesight

Calculate the CGT on your portfolio (including foreign shares) with Sharesight's CGT report. You can also model different sales allocation methods for assets in your portfolio, which could potentially help reduce your capital gains tax.

Illustration of Sharesight's capital gains tax report.

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Frequently asked questions about the CGT reform

When do the new CGT rules take effect?

The new rules apply to capital gains accruing from 1 July 2027. Any gains accrued before that date remain eligible for the current 50% CGT discount. The reform was announced in the 2026-27 Federal Budget but is not yet law.

Do the new rules apply to my existing investments?

Yes — but only to gains accruing from 1 July 2027 onwards. If you bought an asset before 1 July 2027 and sell it after that date, the gain is split based on the asset's deemed value on 1 July 2027. The pre-1 July 2027 portion uses the current 50% discount; the post-1 July 2027 portion uses indexation and the 30% minimum tax floor. These rules apply to assets held by individuals, trusts, and partnerships. The CGT discount for superannuation funds is unchanged, and eligible new residential builds have a separate concession.

What is cost base indexation and how does it work?

Cost base indexation increases an asset's original purchase price (cost base) in line with the Consumer Price Index (CPI) over the holding period. This adjusts for inflation, so only the real gain — the gain above inflation — is taxed. From 1 July 2027, this method will replace the 50% CGT discount for individuals, trusts, and partnerships. For more on how CGT is calculated under current rules, see our CGT guide for Australian investors.

Will I pay more or less tax under the new rules?

That depends on your inflation rate, your return rate, your marginal tax rate, and how long you hold the asset. As a general rule, indexation tends to favour assets where inflation is high relative to returns, while the 50% discount tends to favour assets where returns are high relative to inflation. The 30% minimum tax floor can also change outcomes if your marginal rate sits below 30%. Use the calculator's inflation sensitivity table to see how different scenarios affect your estimated tax.

How will the CGT changes affect property investors?

Property investors are the primary focus of the reform. Existing residential properties retain the 50% CGT discount for gains accrued before 1 July 2027. After that date, indexation and the 30% minimum tax floor apply to most property gains. Eligible new residential builds are an exception — investors can choose between the current 50% discount and the new arrangements (indexation plus the 30% minimum tax floor) when they sell. The reform is paired with changes to negative gearing: from 1 July 2027, losses on existing residential investment properties purchased from 12 May 2026 will only be deductible against income from residential properties, not against other income like wages. Properties held before 12 May 2026 and new builds are exempt from the negative gearing changes.

How will the CGT changes affect ETFs and managed funds?

ETFs and managed funds held by individuals, trusts, and partnerships are subject to the same CGT reform as direct shares. From 1 July 2027, gains will be calculated using indexation, with the 30% minimum tax floor applying to real gains. ETFs and managed funds held inside superannuation funds, including SMSFs, are not affected.

Does this affect my superannuation or main residence?

No. The CGT discount for superannuation funds is unchanged, and the main residence exemption continues to apply.

Does the 12-month holding rule still apply?

Yes. The new indexation method and the 30% minimum tax floor only apply to assets held for at least 12 months — the same threshold as the current 50% CGT discount. Assets held for less than 12 months continue to be taxed in full at your marginal income tax rate, with no change from current rules.

Why is the government replacing the 50% CGT discount?

According to the Treasury, the 50% CGT discount has been criticised for over- or under-compensating investors depending on inflation and returns. The reform is intended to ensure tax is only paid on real (inflation-adjusted) gains and to support housing affordability by reducing tax advantages for property investment. The 30% minimum tax floor is designed to bring effective tax rates on capital gains closer to those paid on wages.

When was cost base indexation last used in Australia?

Indexation was the standard CGT calculation method in Australia from the introduction of CGT in 1985 until 1999, when it was replaced by the 50% CGT discount. The 2026-27 reform reintroduces indexation in a similar form, again using the CPI to adjust the cost base for inflation.

Are these rules final?

Not necessarily. The reform was announced on 12 May 2026 as part of the 2026-27 Federal Budget but has not yet been legislated. The final rules may change as the legislation passes through parliament.

How accurate is the calculator?

The calculator provides an estimate based on the policy as announced. To split your gain across the 1 July 2027 regime change, it uses a straight-line time-based apportionment — the portion of the gain attributed to each period is proportional to the days you held the asset before and after that date. The Treasury fact sheet's worked example uses a slightly different method based on the asset's compound annual growth rate over the holding period, and the ATO's final tools and valuation requirements have not yet been published. Your actual outcome will depend on the final legislation, the asset's deemed value at 1 July 2027, and your specific circumstances. For advice tailored to your situation, speak with a tax professional.

*This Capital Gains Tax (CGT) calculator provides only general estimates for informational purposes. It does not constitute professional tax, legal, or financial advice. While efforts are made for accuracy, results may not reflect all factors or current tax laws. The calculator is mainly for basic CGT estimates on common assets and may not suit every situation or asset type. Users should verify the information and not rely solely on this tool for financial decisions. Always consult a tax professional or the Australian Taxation Office for accurate advice. Sharesight is not liable for reliance on the results, and tax laws are subject to change. Personal data entered is not stored or transmitted.