This excerpt from melbourneit.com.au
Applies to .au domain names
When a .au domain name is registered, it can be transferred between registries immediately (unlike GTLD domains, which have a 60 day embargo period). Your .au domain is always registered for a two year period – .au domains cannot be registered for a longer or shorter period than this.
An .au domain can only be renewed when it is within 90 days of it’s expiry date. When the domain is renewed, two years is added to the existing expiry date – if my domain expired on January 1 2014 and I renewed on October 1, my new expiry date would be January 1 2016. This means there is no penalty for renewing early.
If you chose, you can change the registrant (owner) of your .au domain name during it’s lifespan. If you do so, a new licence is issued in the name of the new registrant for two years. This means that the if you were to transfer the ownership of a domain expiring (for example) March 1 2015 on January 1 2014, the new expiry date would be January 1 2016.
When an .au domain expires, it can be renewed without penalty for 30 days after expiry. There is no redemption phase on .au domains – after the 30 days the domain status changes from “Expired” to “Pending delete”. This lasts 24-48 hours, after which the domain becomes available again.
The full auDA policy on domain expiry can be read at http://www.auda.org.au/policies/index-of-published-policies/2010/2010-01/
Do not gamble on lapsing your registration to avoid losing your domain
It is becoming increasingly common for domain names to be back ordered, which means that your expiring domain name could already be scheduled for registration by another person. Domains are commonly being registered the instant they become available by “domain monetisers” (people who make money by buying and selling domains), who then charge the original domain owner an exorbitant price to regain control of the domain.