Under the Thailand-Australian Free Trade Agreement (TAFTA), goods qualifying as Thai originating goods according to the TAFTA Rules of Origin, may enter Australia at preferential rates of duty. The same Rules of Origin apply for Australian originating goods entering Thailand.
More information on TAFTA is available via the following links.
Australian Customs Notices
Practice Statement and Associated Documents
Claiming preference under the Integrated Cargo System (ICS)
Australian Exporters to Thailand
Example of Thai Certificate of Origin