(from Australian Tax Office)
Fuel tax credits provide businesses with a credit for the fuel tax (excise or customs duty) that's included in the price of fuel used in:
The amount depends on when you acquire the fuel, what fuel you use and the activity you use it in. Fuel tax credits rates also change regularly so it's important to check the rates each time you do your business activity statement (BAS).
Some fuels and activities are not eligible including fuel you use in light vehicles of 4.5 tonnes gross vehicle mass (GVM) or less, travelling on public roads.