Australian tourists travelling to Thailand through one of the international airports on an Australian passport may currently enter Thailand for up to 30 days without obtaining a visa in advance. This is referred to as a “visa exemption”. Australian tourists travelling overland into Thailand through a border crossing may enter Thailand for up to 15 days without obtaining a visa in advance. A visa is required for longer stays or for travellers intending to work or to travel for other than tourism purposes in Thailand.
Thai authorities require all travellers to have at least six months validity remaining on their passports. You may be refused entry to Thailand, or may not be permitted to board your Thailand-bound flight, if your passport has less than six months validity.
Long story short - When it comes to Thailand (or any Southeast Asian country for that matter), make sure you play by their entry / exit rules. Matters can get *very* nasty otherwise. about 9 years ago