Please consult https://www.ato.gov.au/Business/GST/In-detail/Managing-GST-in-your-business/General-guides/The-sharing-economy-and-tax/#Iamprovidinggoodsorservicestopeopleforaf for further details.
If you are perform spare-time activity or pastime pursued for pleasure or recreation then you may be engaged in a hobby, in which case tax or reporting obligations do not apply. If you provide goods or services for payment through a sharing economy website or app where it is more than an occasional pastime or hobby, then the payments you receive are assessable income. This means:
- you must declare the income in your tax return
- you can claim deductions for associated expenses.
You declare the income and any associated expenses for the income year in your income tax return.
Here you can find the differentiation between hobby and business: https://www.ato.gov.au/business/starting-your-own-business/business-or-hobby-/