The Department of Internal Affairs says it will be ready for 19 August - the first day same-sex couples will be able to legally wed.
The department says that from 16 August, all couples will have to use the new "notice of intended marriage" forms as a result of the Marriage Amendment Act which allows two people to marry regardless of their sex, sexual orientation or gender identity.
The Registrar-General of Births, Deaths and Marriages, Jeff Montgomery, is anticipating strong demand from same-sex couples in New Zealand and from other countries.
Mr Montgomery also expects a number of couples to change their civil unions to a marriage.