Whether you own just a few listed shares or have an extensive portfolio, understanding how capital gains tax (CGT) applies when you sell your shares can help you plan your trades effectively. If you trade shares on a scale that amounts to a business of share trading, talk to your tax adviser about the different tax regime that applies.

Each time you sell a parcel of shares, you trigger a “CGT event” and you must work out whether you’ve made a capital gain on that parcel (where the proceeds you receive exceed the cost base) or capital loss (where the cost base exceeds the proceeds). You also trigger a CGT event if you give the shares away as a gift – perhaps to a family member. For tax purposes, you’re deemed to have disposed of the shares at their full market value.

All of your capital gains for the income year are tallied and reduced by any capital losses. This includes your gains and losses from all of your assets that year, not just shares. If you have an overall “net capital gain”, this is included in your assessable income and taxed at your marginal tax rate. If you have a “net capital loss”, you can’t offset this against ordinary income like salary or rental income. Instead, a net capital loss can be carried forward to future years to apply against future capital gains.