As an eligible employer, you can claim the Employment Tax Incentive (ETI) for a maximum of 24 months per qualifying employee, and these 24 months do not need to be consecutive. Here are the details:

The ETI can be claimed for a total of 24 individual months per qualifying employee.
This 24-month period is determined with reference to the period that a qualifying employee is employed, not necessarily the periods during which the ETI is actually claimed.
If, for example, an employer does not claim the ETI for a qualifying employee in a particular month, that month still counts towards the 24 qualifying months.