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What is a valid marriage?

Marriage is defined in Marriage Act 1961 as being: 'the union of 2 people to the exclusion of all others, voluntarily entered into for life'.

For a marriage to be valid:

  • it must be a voluntary union of 2 people
  • it must be solemnised by authorised celebrant, registered minister of religion, state and territory officer or foreign diplomatic or consular officer
  • it must be between parties of marriageable age (18 or over). If one party is 16 years or over the marriage must be authorised by a judge or magistrate
  • parties must not, at time of marriage, be lawfully married to someone else
  • it must not be a prohibited relationship, that is:
    • an ancestor or descendant—(that is their grandparents, parents or their children)
    • a sibling—(that is brother or sister, either of whole- or half-blood—including a sibling by adoption)
    • dependent on when marriage took place—the definition was wider for marriages between 1 February 1961 and 19 June 1977 (inclusive)
  • it must be consented to without duress or fraud
  • it must be made in full knowledge of the identity of the person they are marrying and of the marriage ceremony, and
  • parties must be mentally capable of understanding the marriage ceremony.

Marriages and unions not recognised under Australian law

Celebration of polygamous marriage is not permitted in Australia, however, the Family Law Act 1975 recognises a valid polygamous marriage celebrated overseas, so long as there has been no fraud or duress, parties are over 16 years and mentally capable, the marriage is not between siblings, parents or grandparents, and there is no mistake as to identity of the parties, or nature of ceremony.

Foreign marriages between minors, where one party is 16 years and the other party is less than 16 years are not valid in Australia.

More information


Marriage Act 1961 (Cth)

  • s. 5—interpretation
  • s. 11—marriageable age
  • s. 12—authorisation of marriage of person under age of 18 years in exceptional circumstances
  • s. 23—grounds on which marriages are void
  • s. 23B—grounds on which marriages are void
  • s. 46—certain authorised celebrants to explain nature of marriage relationship
  • s. 88EA—certain unions are not marriages
  • Part IV—solemnisation of marriages

See Marriage Act 1961 (Cth).

Family Law Act 1975 (Cth)

  • s. 6—polygamous marriages

See Family Law Act 1975 (Cth).

Attorney General's Department (Cth)