To be legally married in Australia, a man and woman must:  Not be married to someone else  Not be marrying a parent, grandparent, child, grandchild, brother or sister  Be at least eighteen years old, unless a court has approved a marriage where one party is aged between sixteen and eighteen years old  Understand what marriage means and freely consent to becoming husband and wife  Use specific words during the ceremony  A Notice of Intended Marriage form (NoIM) must be activated with your celebrant at least one month and up to eighteen months before the wedding  You will need to give your celebrant evidence of date and place of birth, identity and the end of any previous marriages for each party. You don't have to be an Australian citizen or a permanent resident of Australia to legally marry here. You can find marriage visa information on the Department of Immigration and Border Protection website, if you hope to live in Australia after your marriage. On the day of your wedding, you will sign three marriage certificates. Each certificate should be signed by you, your celebrant and two witnesses.