Capital Gains Tax Calculator (Investments) Australia

Use this Pro calculator to estimate the capital gains tax on selling an Australian investment, shares or property. It builds the full cost base, applies the 50% discount for assets held over 12 months and any carried-forward capital losses, then taxes the net gain at your marginal rate on top of your other income.

How CGT is calculated

Capital gains tax in Australia is not a separate tax with its own rate. The net gain is added to your taxable income for the year and taxed at your marginal rates. So the tax you pay on a gain depends on your other income: the same gain costs more for a high earner than for someone on a low income.

The calculator works out your total tax with and without the gain and reports the difference as the CGT payable, using the current resident brackets and Medicare levy. This "with and without" approach is more accurate than multiplying the gain by a single rate, because a large gain can straddle two or more brackets: the first slice might be taxed at 30% and the top slice at 37% or 45%. Comparing your whole-of-year tax bill either way captures that bracket creep automatically and shows the genuine marginal cost of the sale.

The cost base and the 50% discount

Your capital gain is the sale price minus the cost base. The cost base is more than the purchase price: it includes buying costs (stamp duty, legal fees), capital improvements, and selling costs (agent commission, legal). Getting the cost base right can noticeably reduce the gain.

If you held the asset for more than 12 months, individuals get a 50% CGT discount, only half the gain is taxable. The calculator shows the tax with the discount, and how much the discount saves you compared with selling inside 12 months.

Carried-forward capital losses

Capital losses from earlier years (or other assets sold this year) can be applied against the gain before the discount, reducing the taxable amount. Enter any carried-forward losses and the calculator subtracts them first, then applies the discount to what remains.

A worked example

Suppose you bought parcels of shares for A$60,000, paying A$400 in brokerage, and sell them 18 months later for A$110,000 with A$550 in selling costs. You also have A$4,000 of carried-forward capital losses from a previous year.

• Cost base : A$60,000 + A$400 + A$550 = A$60,950.
• Raw gain : A$110,000 − A$60,950 = A$49,050.
• Apply losses first : A$49,050 − A$4,000 = A$45,050.
• 50% discount (held over 12 months): A$45,050 × 50% = A$22,525 taxable gain.

That A$22,525 is added to your other income. If your salary is A$95,000, the gain is taxed largely at the 37% marginal rate plus 2% Medicare levy, adding roughly A$8,785 in tax. Had you sold at 11 months instead, no discount would apply and the full A$45,050 would be taxable, nearly doubling the tax. Waiting past the 12-month mark saved you thousands.

The order of operations matters

The sequence is deliberate and easy to get wrong: capital losses are always subtracted before the 50% discount is applied, never after. If you applied the discount first and then the losses, you would overstate your taxable gain and pay too much. The calculator follows the ATO order: net your current-year gains and losses, subtract prior-year losses, then discount eligible gains, so the result reflects the most tax-effective legal outcome. Losses can only offset capital gains, not ordinary income, and unused losses carry forward indefinitely until a future gain absorbs them.

Timing the sale to manage the tax

Because the gain lands in the year you enter into the sale contract, the year you choose to sell can matter as much as the price. Selling in a year when your other income is low, a career break, parental leave, or the year you retire, can mean the gain is taxed in lower brackets. Some investors deliberately spread disposals across two financial years, or bring forward a loss-making sale into the same year as a gain so the loss can be netted off. The calculator lets you test different "other income" figures to see how much your marginal position changes the result before you commit to a sale date.

Common mistakes to avoid

• Understating the cost base. Forgetting stamp duty, brokerage, legal fees and capital improvements inflates your gain and your tax bill.
• Selling just before the 12-month mark. A day short of 12 months means no discount, so check the acquisition date carefully (it is generally contract date, not settlement date).
• Expecting losses to reduce salary tax. Capital losses only offset capital gains; they cannot be deducted against wages.
• Forgetting the gain lifts your marginal rate. A large gain can push part of your income into a higher bracket for that year.
• Assuming the discount applies to companies. The 50% discount is for individuals and trusts; companies do not get it, which affects how you hold an asset.

Assumptions and limitations

The calculator covers the individual resident case with the standard 50% discount. It does not model the CGT main-residence exemption, the six-year rule, partnerships or company/trust rates, or foreign-resident rules. Confirm your cost base and eligibility with a registered tax agent.

This is general information, not tax advice.

About This Investment Capital Gains Tax Calculator

Use this investment 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.