If you earned money in this financial year and are an Australian resident for tax purposes then yes, you will have to lodge an Australian tax return. If you have not paid tax on the money you earned ie; you earned less than the tax free threshold currently at $18,200, and no tax has been withheld by an employee or by Centrelink, then you will still need to lodge a non-lodgement advice instead. If you don’t, the ATO will assume you need to lodge and take action to force you to lodge.