To get married in Australia, you must not be married, not be marrying a parent, grandparent, child, grandchild, brother or sister, be at least 18 years old (unless a court has approved a marriage where 1 person is 16-18 years old), understand what marriage means and freely agree to marry, use specific words during the ceremony, give a notice of intended marriage form to an authorised marriage celebrant at least 1 month and no more than 18 months before your wedding AND be married by an authorised marriage celebrant.