Hi David72,
There is no clear answer to that. Easiest way to put it is (1) what you negotiate between you or (2) what the family court decides.
What was the nature of your relationship prior to separation, were you married or de facto (this usually requires that you ahve either been together at least 2 years or had a child together)? Persons who are in these types of relationships which have broken down can apply to the family court for orders regarding property divisions, however generally there are time limitations as to how long after separation (in the case of de facto couples) and divorce (in the case of married couples) you have to bring such an application.
If the family court is to determine your matter it follows a four-step process in arriving at a just and equitable outcome for both partners:
It considers: the total value of all joint assets, the financial and non financial contributions of each party and future needs of each party.
This is a very commonly considered topic on this forum, check out this recent thread:
SA - Separation with Partner - Get More than 50% of Property Settlement? | LawAnswers.com.au