Most people only think about relationship property law at one of two moments: when a relationship is beginning and feels permanent, or when it has ended and feels anything but. Both moments call for the same tool. A properly drafted relationship property agreement, and both are moments when people are least inclined to pick up the phone and ask for one.

The Property (Relationships) Act 1976 governs how property is divided between couples, whether married, in a civil union, or in a de facto relationship of three years or more. Without an agreement, the Act's default rules apply, and those defaults do not always match what either person actually wants.

Getting married, or moving in together

A contracting out agreement, commonly known as a ‘pre-nup’, is made under section 21 of the Act. It allows a couple to decide in advance how property will be divided if the relationship ends, rather than leaving it to the Act's default sharing rules.

These agreements are not just for people with significant existing wealth. They matter for anyone bringing something into the relationship that they want protected, a family home, a business, an inheritance, or shares in a company. They are especially common for blended families, where one or both partners want to preserve assets for children from an earlier relationship.

The Act sets specific requirements for these agreements to be enforceable. Each party must receive independent legal advice before signing, and the agreement must be in writing and witnessed correctly. An agreement drafted without meeting these requirements can be set aside by the Family Court, which defeats the entire purpose of having one.

The best time to have this conversation is well before the wedding or the move-in date, not the week before. Rushed agreements signed under time pressure are more vulnerable to later challenge, and no one wants their relationship property agreement to become the first major disagreement of the relationship.

Getting unmarried

When a relationship ends, a separation agreement under section 21A of the Act sets out how property will actually be divided, rather than relying on default entitlements that either party has to apply to the Court to enforce.

A good separation agreement covers more than who keeps the house. It should address the family home and any mortgage, KiwiSaver and superannuation splitting, business interests, trusts, debts, and, where relevant, ongoing financial support. Left unresolved, these issues tend to resurface later, usually at a worse time and often through lawyers on both sides.

As with contracting out agreements, separation agreements require independent legal advice for both parties to be binding. This is not a formality to be worked around. It is the safeguard that makes the agreement stand up if either party later has second thoughts.

Whether a couple is getting married or getting unmarried, the underlying question is identical: what happens to the property if things do not go the way either person expects? Addressing it early, with proper advice on both sides, is what makes an agreement actually hold up. Addressing it late, or not at all, is what fills up the Family Court's list.

The takeaway

A relationship property agreement is not a sign of mistrust. It is a practical document that removes ambiguity at exactly the point in a relationship, beginning or end, when clear thinking is hardest to come by. Whether you are planning a wedding or working through a separation, getting advice early gives you options that are much harder to create after the fact.