To correctly determine whether a worker is an employee or contractor, you need to look at the whole working arrangement. A worker isn't automatically a contractor just because they have an ABN or specialist skills or you only need them during busy periods. Your tax, super and other government obligations will vary depending on whether your worker is an employee or contractor.
Use the ATO online Employee/Contractor decision tool to work out your obligations.
Are you engaging a worker in the building and construction industry? Use the Building & Construction Industry - Employee/Contractor decision tool.