Australian common law allows a person to change their name simply by taking and using the name. However, this is not enough to satisfy businesses or organisations, like banks, government agencies and other places. These places require legal evidence you have changed your name.
The way to get this legal evidence is to change your name with your local Births, Deaths and Marriages (BDM) Registry. Anyone in Australia can change their name to almost any name they like whenever they like, as long as they are not changing their name for criminal purposes (ie. committing fraud).
A legal change of name is as simple filling out the form at your local BDM, paying a fee and collecting your name change certificate. Fees for changing your name across Australia range from $55 to $180 depending on your state/territory. When your new name is legally registered, you will need to provide copies of your name change certificate to all the offices, banks, agencies etc where you need to change your name.
Find your local BDM registry and follow the links to ‘Change of Name’