Capital Gains Tax Calculator Australia

What the Capital Gains Tax Calculator Does

The capital gains tax calculator estimates the CGT you may owe when you sell an asset such as shares or an investment property. It applies the 50% CGT discount for assets held longer than 12 months, taxes the remaining gain at your marginal rate, and shows your net profit after tax. Instead of guessing at your after-tax proceeds, you get a clear estimate before you commit to a sale.

Capital gains tax in Australia is not a separate flat tax. A net capital gain is added to your income for the year, which is why the tool asks for your marginal rate and considers how long you held the asset.

How Capital Gains Tax Works in Australia

When you sell an asset for more than it cost you, the difference is a capital gain. That gain is included in your assessable income and taxed at your marginal rate. Three inputs drive the outcome:

• The sale price you receive for the asset
• The cost base , broadly what you paid plus associated costs
• The holding period , which determines whether the discount applies

If you sell for less than the cost base, you make a capital loss. Losses cannot reduce your ordinary income, but they can offset other capital gains in the same year or be carried forward to future years.

The Role of the 50% Discount

The most important feature for long-term investors is the CGT discount. For eligible assets held more than 12 months, only half the gain is taxable. This single rule can dramatically change the outcome of a sale and is often the reason investors wait past the 12-month mark before selling.

The calculator handles this automatically. When you indicate the asset was held for more than a year, it halves the taxable gain before applying your marginal rate. When it was held for a year or less, the full gain is taxed.

How to Use the Calculator

Getting an estimate takes only a few inputs:

1. Enter the sale price of the asset.
2. Enter your cost base, including purchase price and associated costs.
3. Add any selling costs, such as agent or brokerage fees.
4. Indicate whether you held the asset for more than 12 months.
5. Select or enter your marginal tax rate.

The tool then shows your gross gain, the taxable portion after any discount, the estimated tax, and your net profit.

Why Accuracy of the Cost Base Matters

A common and costly mistake is understating the cost base. The cost base is more than the purchase price. It can include:

• Brokerage or agent fees on purchase
• Legal and transfer costs
• Certain capital improvements to a property

Every dollar you correctly add to the cost base reduces your taxable gain. Keeping thorough records from the day you acquire an asset can meaningfully lower the tax when you eventually sell.

Planning Around Capital Gains Tax

Because a capital gain is added to your income, the timing of a sale matters. Selling in a year when your other income is lower can reduce the marginal rate applied to the gain. Spreading disposals across financial years, or realising a loss to offset a gain, are strategies many investors consider.

• Hold past 12 months where practical to access the discount.
• Match gains and losses in the same year to reduce the net taxable amount.
• Consider your income year so the gain is not taxed at your highest possible rate.

These are general considerations, not recommendations. Your circumstances, and the current thresholds and rules the calculator applies, determine the right approach.

Capital Gains on Different Assets

The calculator works for any asset that attracts CGT, but the details differ by type. When you sell shares or managed funds, the cost base is usually straightforward: the purchase price plus brokerage. When you sell property, the picture is more complex, because the cost base can include stamp duty, legal fees, and capital improvements made over the years you owned it.

Your main residence is generally treated differently from an investment property, and some assets acquired before capital gains tax existed may be exempt. These distinctions can significantly change the outcome, so it is worth understanding which rules apply to the specific asset you are selling.

• Shares and funds: cost base is typically purchase price plus brokerage.
• Investment property: cost base can include acquisition costs and capital improvements.
• Collectables and personal-use assets: special rules and thresholds may apply.

Because the treatment varies so much, use the calculator as a general estimate and confirm the correct cost base and any exemptions for your particular asset before relying on the figure.

Reading and Using Your Result

Treat the figure as an estimate to guide planning, not an exact assessment. The calculator uses the up-to-date rates and discount rules it maintains, but your final position depends on your complete tax situation, including other income, offsets, and any losses carried forward.

Use it to compare scenarios: what your net profit looks like if you sell now versus after passing the 12-month mark, or how a different marginal rate changes the outcome. Seeing those differences before you sell helps you make a more informed decision and avoid surprises at tax time.

For a transaction of any size, confirm your position with the relevant tax authority or a registered tax agent before acting.

This article is general information only and is not financial advice.

About This Capital Gains Tax Calculator

Use this capital gains tax calculator to get an instant, accurate estimate. The figures follow official ATO guidance and every rate and threshold is kept up to date for 2026. Adjust the inputs above to match your situation, or browse all our calculators to plan your next step.