Australian Capital Gains Tax Calculator

Capital gains tax in Australia is not a separate tax — it is part of your income tax. When you sell (or otherwise dispose of) a CGT asset, the resulting capital gain is added to your assessable income and taxed at your marginal tax rate. That means the amount of CGT you pay depends on what other income you earn in the same financial year.

The ATO recognises over 50 different CGT events, but the most common is CGT event A1 — disposing of an asset by selling, gifting, or transferring it. The core formula is straightforward:

Capital gain = Capital proceeds − Cost base

The full process works in five steps: (1) identify the CGT event and confirm the asset was acquired after 20 September 1985 (pre-CGT assets are exempt), (2) determine your capital proceeds (usually the sale price), (3) calculate your cost base (purchase price plus all allowable costs), (4) apply any capital losses, and (5) apply the 50% CGT discount if eligible. The calculator above handles all five steps automatically — you just enter your numbers.

For a complete walkthrough with worked examples, see our guide to capital gains tax in Australia.

Your cost base is the single biggest factor in determining how much CGT you pay. The ATO defines five elements that make up the cost base of a CGT asset:

1. Money paid for the asset — the purchase price, plus brokerage for shares
2. Incidental costs of acquisition — stamp duty, conveyancing fees, valuation costs
3. Non-deductible ownership costs — costs of owning the asset that you couldn't claim as a tax deduction (e.g. interest on a non-income-producing asset)
4. Capital expenditure — renovations, extensions, or structural improvements that increase the asset's value
5. Costs of disposing — real estate agent commissions, legal fees on sale, advertising costs

These costs add up. For example, $27,000 in stamp duty on a $750,000 investment property saves approximately $6,075 in CGT at the 45% marginal rate (after applying the 50% discount). For shares, note that buy brokerage falls under Element 1 and sell brokerage under Element 5. You can enter all of these in the calculator's advanced mode using the cost base fields.

See asset-specific cost base breakdowns in our investment property CGT guide and shares and ETF CGT guide.

The CGT discount is the single most valuable concession for Australian taxpayers. If you hold an asset for at least 12 months before disposing of it, you can reduce your capital gain by:

• 50% for individuals and trusts
• 33.33% for complying superannuation funds
• 0% for companies — no discount available

The 12-month clock starts the day after acquisition and runs to the disposal date. If you bought shares on 15 January 2025, the earliest disposal date to qualify for the discount is 16 January 2026. Selling on 15 January 2026 is one day too early. The calculator above checks this automatically based on the dates you enter.

Foreign residents lost access to the CGT discount for gains accruing after 8 May 2012. If you became a non-resident after holding an asset as a resident, you may still receive a proportional discount for the period you were a resident.

There is one critical ordering rule that catches people out: capital losses must be applied before the discount. If you have a $100,000 gain and $20,000 in losses, you subtract the losses first ($80,000) and then apply the 50% discount ($40,000 taxable). Getting this wrong — discounting first, then subtracting losses — would give you $30,000 taxable, which understates your obligation by $10,000.

For a deep dive, see our complete guide to the 50% CGT discount.

Capital losses occur when your cost base exceeds your capital proceeds. Unlike capital gains, capital losses can only be offset against capital gains — you cannot deduct them from your salary, wages, or other ordinary income. However, unused losses carry forward indefinitely with no time limit, so they remain available to offset future gains.

The correct ordering for applying losses is:

1. Apply current-year capital losses against current-year gains
2. Apply carried-forward losses from previous years
3. Then apply the 50% CGT discount to the remaining net gain

One additional rule: losses on collectables (artwork, jewellery, rare coins) can only be offset against gains on other collectables — they cannot reduce gains on shares, property, or other assets. The calculator handles this quarantining automatically when you select the collectable asset type.

Different asset types have different cost base rules and common pitfalls. Here are the key considerations for the three most common CGT assets in Australia.