The technical trigger that crystallises a capital gain or loss for tax purposes - most commonly the disposal of a CGT asset.
There are over 50 CGT events defined in the ITAA 1997. The most common for property investors is Event A1 (disposal of a CGT asset) under s 104-10. Other events relevant to property include E1 (creating a trust), E4 (capital payment from a trust), and rollover events. Byrz models Event A1 only.