When to pay
Although it sounds like it, capital gains tax isn’t a separate tax. Your net capital gains form part of your assessable income in whatever year your capital gains tax happened.
Capital gains tax is payable as part of your income tax assessment for the relevant income year.
When not to pay
If you make a net capital loss in an income year, you shouldn’t pay capital gains tax. But the net capital loss is unable to offset tax on any other income, and can only be ‘carried forward’ to offset capital gains in future income years.
It’s worth noting, some assets and events are exempt from capital gains tax. These include selling your principle home or personal car, or selling an asset acquired before capital gains tax was introduced on 20 September 1985.
Have a read of the ATO’s full list of capital gains tax exemptions.
Working out your capital gain (or loss)
To quickly figure out how much capital gains tax you’ll pay - when selling your asset, take the selling price and subtract its original cost and associated expenses (like legal fees, stamp duty, etc.). The remaining amount is your capital gain (or loss).
If you’ve made a capital gain and you've held an asset for greater than 12 months (assuming you don’t have other capital losses), you can apply the 50% discount to work out your net capital gain (unless the indexation method applies).
Companies and individuals pay different rates of capital gains tax. If you’re a company, you’re not entitled to any capital gains tax discount and you’ll pay 30% tax on any net capital gains. If you’re an individual, the rate paid is the same as your income tax rate for that year. For SMSF, the tax rate is 15% and the discount is 33.3% (rather than 50% for individuals).