Australian CGT calculator

Australia's CGT rules are changing on 1 July 2027. The 50% discount is being replaced with two new rules: your cost base will be adjusted for inflation, and a 30% minimum tax rate will apply to capital gains. This calculator estimates how your tax bill might change.

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

$228,262

Net gain after tax: $571,738

Transitional · split pre/post 1 Jul 2027


Nominal gain	$800,000
Effective CGT rate	28.5%
Applied rules	Transitional · split pre/post 1 Jul 2027
Difference in tax payable*	+$40,262 (+21.4%)

*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 a CAGR model of capital gains to determine the 1 July 2027 value - 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	1826 days
Apportioned gain	$331,371
Taxable amount	$165,685*
Marginal tax rate	47.0%
Tax on this portion	$77,872

*50% discount applied as investment held over 12mo

Post-1 July 2027

Time held	1826 days
Deemed value at 1 Jul 2027	$1,131,371
Indexed cost base (2.5% over 1826 days)	$1,280,021*
Taxable gain	$319,979
Marginal tax rate	47.0%**
Tax on this portion	$150,390

*Indexation applied as investment held over 12mo

**Marginal tax rate exceeds 30% minimum tax rate

Total tax payable:

$228,262

Effective CGT rate: 28.5%

Rule calculation comparison

Compare what tax would have been paid under the current rules (50% CGT discount) to the new rules (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:

$188,000

Effective CGT rate: 23.5%

New rules · from 1 Jul 2027

Total tax payable:

$270,704

Effective CGT rate: 33.8%

Show breakdown

Nominal gain	$800,000
Taxable amount	$400,000*
Marginal tax rate	47.0%

*50% discount applied as investment held over 12mo

Cost base	$800,000
Indexed cost base (2.5% over 3652 days)	$1,024,033*
Taxable gain	$575,967
Marginal tax rate	47.0%**

*Indexation applied as investment held over 12mo

**Marginal tax rate exceeds 30% minimum tax rate

Inflation sensitivity

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

Tax payable

Inflation p.a.	Current rules	Transitional	Difference
1.00%	$188,000	$271,007	+$83,007
2.00%	$188,000	$242,791	+$54,791
2.50%	$188,000	$228,262	+$40,262
3.00%	$188,000	$213,447	+$25,447
4.00%	$188,000	$182,941	-$5,059
5.00%	$188,000	$151,239	-$36,761
6.00%	$188,000	$118,307	-$69,693
7.00%	$188,000	$84,108	-$103,892
8.00%	$188,000	$77,872	-$110,128

This calculator attempts to model the impact of the Budget 2026-27 announcement (12 May 2026) for individuals. Please see the FAQs below for details relating to exclusions, methodologies and assumptions. This model provides estimates only, based on the policy as announced and information currently available. This is a model, not tax advice — consult a registered tax adviser before acting.

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 for individuals, partnerships and trusts, working alongside the 30% minimum tax rate, 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% minimum tax rate 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 rate

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

Taxable income and marginal tax rate

Select the bracket your other taxable income falls into to determine your marginal tax rate. Most individuals pay a 2% Medicare levy on top, tick the box to include this if it applies to you under ATO rules.

Incidental costs

Any additional costs incurred as part of buying or holding the asset that have not already been tax deductible, such as brokerage fees, spreads or taxes.

Eligible new residential build property

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.

What methodology applies to transitional arrangements (assets held over 1 July 2027)?

For assets you hold over 1 July 2027, the portion of the gain accrued before that date is taxed under the 50% CGT discount, and the portion after that falls under the new indexation method and 30% minimum tax rate. The asset’s value at 1 July 2027 becomes the cost base used to calculate the post-1 July 2027 portion of the gain under the new indexation method. The government will allow you to set that value via a formal valuation, or a tool that the ATO will supply. The ATO tool hasn’t been published yet, so our calculator estimates the 1 July 2027 value using a compound annual growth rate (CAGR) apportionment method. We’ve chosen CAGR over a simple linear apportionment based on the Treasury fact sheet's worked example — our best guess at the government’s intended approach based on the information available so far.

How accurate is the calculator?

The calculator provides an estimate only, based on the policy as announced and information currently available. The calculations we’ve used for transitional arrangements have required us to make some guesses and assumptions regarding methodology, as the details of 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.