Employee Share Option Plans - or ESOPs - give you an option to receive a share. That option might vest in the future, or it might not. Hence, taxation occurs only at the vesting point. Or in other words: The taxation point is at the point of vesting.

PSI in TR 2022/3 - steps 7 to 9 is about the employees test, business premises test as well as ATO PSI Determinations and of course the special agent rules.