Changing your surname to your spouse's name after you are married is a custom and not required by law.
If you would like to change your surname and you were married in Australia, then you do not need to formally apply for a change of name with the Registry of Births, Deaths & Marriages.
You can immediately start using your new married name.
What you will need to do is tell everyone your new name such as banks and government agencies like Medicare and change all your personal documentation such as driver's licence and passport.
Different organisations have different requirements to change your name in their system so you will need to:
1. make a list of who you need to tell (examples below)
2.contact each organisation and ask them what evidence do they need AND what is the process eg by letter, visit to their office, by email etc.
In most cases they will want to at least see your "official marriage certificate".
The official marriage certificate is not the commemorative (ie pretty) certificate you are given at your wedding ceremony.
Even though you are married and your celebrant registered your marriage, you must still apply for the official certificate which involves three forms of ID and a registration fee.
Check out my Blog of 26 January where I explain what's involved in obtaining an official marriage certificate. My gift to each of my wedding couples is to prepare the application, lodge and pay the registration fee for the official marriage certificate -all you do is sign the application.
If you were born overseas and married here those organisations you need to change your name with may require you to formally apply to the Registry for a change of name and the official marriage certificate may not be sufficient. Just ask them.
Who To Tell
passport, driver's licence, car registration, bank accounts, credit cards, Australian Tax Office, local council, Australian Electoral Commission, Medicare, private health fund, insurance policies, doctor & dentist, superannuation, accountant, your will (talk to your lawyer) subscriptions, memberships, landlord if you rent, body corporate if you own a unit.