Fringe benefits tax (FBT) is a tax employers pay on certain benefits you provide to your employees, including your employees' family or other associates. The benefits may be in addition to, or part of, salary or wages packages. FBT is separate from income tax.
If you were required to pay FBT of $3,000 or more in the past financial year, then you need to lodge your BAS and pay quarterly.
See also:
How to complete labels F1, F2, F3, F4, 6A and 6B on your BAS.