People often seek an answer to this question because it has a financial impact on them. Family courts have jurisdiction to make orders in respect to maintenance and property settlement between persons living in de facto relationships if they are satisfied that there is a de facto relationship, and the total of the periods of that relationship are at least 2 years; or that there is a child of the de facto relationship; or that the claimant has made direct or indirect financial and/or non-financial and/or homemaking contributions to their property and a failure to make an order would result in serious injustice to the claimant.
You cannot be in a de facto relationship with another person if you are married to that person, or if you are the child or adopted child or descendant of the other person; or you have a parent in common, who may be an adoptive parent of either or both of you.
The Family Law Act states that you will be in a de facto relationship with another person if, having regard to all the circumstances of your relationship, you have a relationship as a couple living together on a genuine domestic basis. Unfortunately this definition is as clear as mud in today’s complex society and it is often necessary to undertake a detailed enquiry into the multiple aspects of a relationship to determine whether 2 persons are together as companions, or as friends with benefits, or a couple living together on a genuine domestic basis.
One size does not fit all, and one judge has questioned rhetorically, “how then is a judge expected to decide whether a relationship between a man and a woman (or indeed under this legislation same-sex couples) is marriage like in circumstances where married couples straddle the spectrum from the deliriously happy to the homicidally estranged?”