Do you need to lodge a tax return if your taxable income is under the tax free threshold?- by Brenda
Conditions which require you to lodge a tax return
• Your PAYG (pay as you go) has been withheld from payments received during the year.
• There is a reportable fringe benefits amount or employer superannuation contributions on your PAYG payment summary.
• You are entitled to the private health insurance refund but did not claim what you are entitled to.
• You are an Australian resident for tax purposes and had exempt foreign employment income and $1 or more of other income.
• You made or can claim a loss made in a preceding year.
• You are a liable or recipient parent under a child support assessment, except if both of the following conditions are applied:
• You are a recipient of one or more Australian Government allowances, pensions or payments for the whole year.
Source from ATO.