The following is taken from the Australian Customs Service TRS for travellers link, which says in part:

About the Tourist Refund Scheme (TRS)

The TRS enables you to claim a refund, subject to certain conditions, of the goods and services tax (GST) and wine equalisation tax (WET) that you pay on goods you buy in Australia.

To claim a refund you must:
  • Spend $300 (GST inclusive) or more in the one store and get a single tax invoice
  • Buy goods no more than 30 days before departure
  • Wear or carry the goods on board the aircraft or ship and present them along with your original tax invoice, passport and international boarding pass to a Customs Officer at a TRS facility
  • Claims at airports are only available up to 30 minutes prior to the scheduled departure of your flight.
  • Claims at seaports should be made no earlier than 4 hours and no later than 1 hour prior to the scheduled departure time of the vessel.
The refund only applies to goods you take with you as hand luggage or wear onto the aircraft or ship when you leave Australia. It does not apply to services or goods consumed or partly consumed in Australia, such as wine, chocolate or perfume. However, unlike other tourist shopping schemes, most of the goods, such as clothing and cameras, can be used in Australia before departure.

The TRS is open to all overseas visitors and Australian residents, except operating air and sea crew.

The GST refund is calculated by dividing the total amount of the purchase by 11. The WET refund is 14.5 percent of the price paid for wine. For example, if you buy goods for a GST-inclusive price of $660 you will receive a refund of $60. If the $660 is made up of a camera ($460) and wine ($200), you will receive a total refund of $89 (total GST refund of $60 plus $29 WET refund on the wine).

More details available from Australian Customs Service's Advice for travellers link here, including the following topics: