Selecting tax class is crucial for system to withhold correct amount of tax. Tax Class is provided by the Tax Office and is usually derived from Tax File Number declaration that the Employee provides. Employee can complete TFN declaration on Employee Portal, or you can do it yourself:
Menu: Staff > Payroll > Employees > List / select the employee / Payroll Details tab > Employee tax details link.
Employee can only complete TFN declaration. You can either complete the declaration and let the system select correct tax class, or you can select the tax class directly.