If you change an employee's Tax Details or the information on their TFN Declaration, this may change the employee's Income Type. When the Income Type is changed for an employee, you will be asked how you want to apply the changes.
If you select 'Yes', then the Income Type will be changed for the whole of the tax year, meaning that any previously reported transactions will be attached to the new Income Type.
If you select 'No', then the Income Type will be applied from the next period, meaning that the employee's earnings will be split between multiple Income Types.