Capital Gains Tax Calculator

People look for a capital gains tax rate and there is not one. A net capital gain is added to your taxable income for the year of the CGT event and taxed at your marginal rate, so the same gain costs a different amount depending on what else you earned that year.

That is why this calculator asks for your other income. It works out your tax bill without the gain, then with it, and the difference is the capital gains tax. A tool that applies a flat percentage to the gain is answering an easier question than the one you asked.

It also means the year you sell in is a lever. A gain landing in a year when your income is low costs less than the same gain in a year when it is high.

The CGT event happens when you sign the sale contract, not when it settles. A contract signed in late June with settlement in August falls in the earlier financial year, which can mean the tax is payable on a gain before the money has arrived.

The same rule applies at the other end, so the twelve months that earns the discount is measured contract to contract. Eleven months and three weeks gets you nothing, and a sale signed a week early can cost half the discount on the whole gain.

This is why the calculator takes two dates rather than a number of years. The precision is not decoration; it decides both the discount and, now, which set of rules taxes which part of your gain.

Capital works deductions claimed while you held the property come off the cost base. Claim $12,000 a year for ten years and your cost base is $120,000 lower, so the gain is $120,000 higher.

This catches people out because the deduction felt like a benefit at the time and the bill arrives years later. Put what you claimed into the capital works field and the tool shows the effect rather than hiding it.

Taking the deduction is still usually the better order. It reduces taxable income at your marginal rate every year you hold, and only half of what it adds back is taxed if you qualify for the discount. But it is a deferral, not a gift, and it should be in the number you plan around.

The rule bites even if you did not claim. Where you were entitled to a capital works deduction, the cost base is generally reduced whether or not you actually took it, so there is rarely an advantage in leaving it unclaimed.

The Treasury Laws Amendment (Tax Reform No. 1) Act 2026 received assent on 26 June 2026. From 1 July 2027 it replaces the 50% discount, for individuals, trusts and partnerships, with cost base indexation and a minimum tax rate of 30% on real capital gains.

Indexation lifts the cost base with inflation so you are taxed on the above-inflation profit rather than the whole nominal gain. Whether that is better or worse than half the gain depends entirely on inflation over your holding period, which is why nobody can tell you in advance which regime treats you more kindly.

It turns on when the gain accrues, not when you sell. The 50% discount still applies to gains accruing up until 1 July 2027, and the new arrangements apply to gains accruing after. A property bought before and sold after has a gain in two parts.

An investor who buys a new build can choose either the 50% discount or indexation, and recipients of certain government payments including the Age Pension and JobSeeker are exempt from the 30% minimum.

It does not print a post-2027 tax figure. When a hold straddles 1 July 2027 the tool shows the share of the holding period each side of the line and stops there.

That is a deliberate refusal rather than an omission. The Act lets a taxpayer elect between a market valuation of the property at 1 July 2027 and an apportionment method, and the two produce different answers. The formula and the indexation reference periods are not yet published in a form anyone can cite. A calculator that produced a confident dollar figure from that would be inventing precision on a tax page, and we would rather show you the shape of the split honestly.

Three other things are outside it. It assumes an individual, so company and trust rates do not apply. It does not handle the main residence exemption or its apportionment, which turns on dates and use in a way no web tool resolves. And it takes no account of capital losses carried forward from earlier years, which offset gains before the discount is applied.

If any of those are in play, the number here is a starting point for a conversation with your accountant rather than an answer.