An International Drivers Permit (IDP) is a translation of the category/s of vehicles on your Australian drivers licence into an internationally recognised symbol system. This is a widely recognised document accepted in most countries globally, when carried with your Australian drivers licence.
An IDP allows you to drive overseas without further tests or applications, provided your Australian drivers licence is still current. Many car hire companies’ state in their terms and conditions of the hire agreement, that you are required to hold an IDP.
In some countries it is a requirement of the country that you hold the permit. This requirement is for the country only. This is separate to any requirements or needs by a car hire or insurance company (even if the country does not require it, car hire or travel insurance companies may still).
Whilst the Australian Automobile Association (specifically RAC in WA) makes every effort to have the most up to date information regarding an IDP, it is ultimately the responsibility of the traveller to contact local motoring authorities of the country of destination to find out the requirements of documents they are required to hold, prior to travelling.
What if I don't have an IDP? Whilst you may not be asked to present your IDP when travelling, it may still be a requirement to hold one. Failure to do so may result in the inability to pick up a rental vehicle. It may also trigger exclusions under your travel insurance policy, if claiming for loss or damage caused while driving a motor vehicle overseas.