There are several ways you can participate if you’re overseas, depending on whether you are a registered overseas elector or are still enrolled at your Australian address.
You have the option to ask a trusted person to receive your form on your behalf, open it, complete it based on your instructions and return it to the ABS. More information about this option can be found here.
You can also request a Secure Access Code from the ABS through the Information Line (1800 572 113 or +61 2 6252 5262 from overseas, 7 days a week, 8am - 8pm) or the ABS website until 20 October 2017. Then you will be able to complete the plebiscite online, via the automated telephony service or via a call centre.