It is not uncommon for spouses or domestic partners to die at the same time or within a short time of each other. Before 1 January 2025, there was no codified presumption under South Australian law to provide certainty as to the legal effect of such deaths. Where there was no proof of who died first, it would sometimes be necessary to apply to the court for guidance as to the distribution of the estates.

Because of this legal uncertainty, testators often provided for this situation in their will by including a clause that set out the period for which their spouse or partner must outlive them in order to be considered to have "survived" them (usually 28 days, consistent with the previous law for dying intestate [but see Succession Act 2023 (SA) s 101(4) which has increased this to 30 days]). A clause would also be included that clarified that if 2 spouses or partners died together or the order of their deaths was uncertain, the deaths were to be taken to have occurred in order of seniority (in other words, the older of the 2 would be taken to have died first).

From 1 January 2025, s 126 of the Succession Act explicitly provides for this, clarifying that when 2 persons die in circumstances where it is uncertain who died first, the oldest will be taken to have died first, and the younger will be taken to have survived the elder by a period of 1 day.

New s 127 of the Succession Act 2023 (SA) also clarifies that where 2 or more persons who jointly own property die in an order that is uncertain, the jointly-owned property will pass as if the joint owners held the property as tenants in common in equal shares.