How long does a prenup last in NZ
Updated 2026-08-09. General information, not legal advice.
A prenup in New Zealand lasts indefinitely. A contracting out agreement under the Property (Relationships) Act 1976 has no expiry date and does not lapse when you marry, have children or hit an anniversary. It stays in force until the two of you replace it with a new agreement, or a court sets it aside. The practical risk is not expiry but ageing: an agreement that was fair when signed can become unfair as life changes, and the more unfair it becomes, the easier it is to challenge.
Does a prenup expire after marriage or after time?
No. Unlike some overseas jurisdictions, NZ law has no rule that an agreement lapses on marriage or after a set number of years. An agreement signed as a de facto couple continues to apply if you later marry, provided it was drafted to say so, which well-drafted agreements are. If yours predates a marriage and never contemplated one, have it reviewed, because coverage gaps, not expiry, are the real risk.
Some couples deliberately include a review clause or a sunset clause, for example an agreement that softens after ten years or on the birth of children. That is a design choice, not a legal requirement, and it needs careful drafting so the agreement does not simply fall away.
When should you update a prenup?
Review the agreement at every major life event: marriage or civil union, children, buying or selling a home, a business starting or growing, a trust being settled, a significant inheritance, or a move overseas. The test is simple: does the agreement still describe your actual life? An agreement about two flats and two KiwiSavers does not answer questions about the company you built together five years later.
Updating means signing a new agreement or a formal variation, and the section 21F formalities apply again: independent advice, witnessing and certification for both partners. A handwritten amendment or an email agreeing changes has no effect.
What ends a prenup?
Three things. Replacement: a new certified agreement supersedes the old one. Court order: a court can set an agreement aside for serious injustice under section 21J, or find it void for missing the formal requirements. And performance: once the relationship ends and property is divided according to the agreement, it has done its work. Separation itself does not cancel the agreement; separation is precisely when it operates.
Common questions
- How long does a prenup last in NZ?
- Indefinitely. A contracting out agreement has no expiry date and remains in force until replaced by a new certified agreement or set aside by a court. Regular reviews at major life events keep it fair and therefore durable.
- Does a prenup still apply after we get married?
- A properly drafted agreement signed before marriage continues to apply after it, because agreements are made in contemplation of the relationship continuing into marriage. If your agreement was signed years before marrying and never mentions marriage, have it reviewed.
- Can we change our prenup later?
- Yes, at any time, by agreement. The change must go through the same formalities as the original: written, signed, independent legal advice for each partner, witnessing and certification. Informal changes have no legal effect.
- Does an old unfair prenup still count?
- It remains technically in force, but age and changed circumstances feed directly into a section 21J challenge: a court can set aside an agreement where enforcing it would now cause serious injustice. The older and more outdated the agreement, the weaker its protection.
Sources
All information published on prenup.nz, including this guide, is general information only and is not to be construed as legal advice. We strongly recommend seeking independent legal advice about your own situation. A contracting out agreement only binds you once each partner has taken independent legal advice and a lawyer has witnessed and certified each signature, as section 21F of the Property (Relationships) Act 1976 requires.