Remember, the FBT year is different to the income tax year. The FBT year is from 1 April until 31 March. Like income tax, you must lodge a return at the end of each year, in this case a Fringe benefits tax (FBT) return. 

The date you need to lodge your return by can differ. If you lodge your own return the due date is 21 May. If a registered tax agent lodges for you, the lodgment date may be 21 May or 25 June, depending on circumstances. Your tax agent will know which date applies.