Financial agreements for WA de facto couples: the rules that differ from the rest of Australia

A binding financial agreement lets a couple decide for themselves how their property will be divided if they separate, without a court making that decision. Across most of Australia these agreements are made under the Family Law Act 1975 (Cth). For de facto couples in Western Australia they are not.

WA kept its de facto property powers rather than referring them to the Commonwealth, so a WA de facto couple cannot make a de facto agreement under the federal Act (s 90UA, read with s 90RA(3)). Their agreement is made under Part 5A of the Family Court Act 1997 (WA). The WA rules for when such an agreement is binding are older and stricter than the federal ones, and an agreement built from a template written for another state can fail on a technicality.

Married couples in WA, and couples who are about to marry, use the federal Act like everyone else.

The three kinds of WA de facto agreement

The WA Act allows a financial agreement:

(a) before a de facto relationship starts (s 205ZN);

(b) during the relationship (s 205ZO); and

(c) after it ends (s 205ZP).

Any of them can deal with property, financial resources and maintenance. Since 28 September 2022 they can also deal with superannuation, which is then split under federal law (s 205ZPA). If the agreement is binding and covers the matter, the court cannot make its own property order about it (s 205W).

When the agreement is binding: s 205ZS

Section 205ZS(1) says a WA de facto agreement is binding only if all of these are met:

(a) it is signed by both parties;

(b) the agreement itself contains, for each party, a statement that before signing they received independent legal advice about the effect of the agreement on their rights and its advantages and disadvantages to them at that time;

(c) an annexure to the agreement contains a certificate, signed by each adviser, stating that the advice was given;

(d) it has not been terminated or set aside by a court; and

(e) after signing, the original agreement is given to one party and a copy to the other.

Why a federal template can fail in WA

Three of those requirements differ from the federal rules in s 90G.

The statement has to be inside the agreement

Under the federal Act, each lawyer gives their client a signed statement that advice was provided, and copies are exchanged. In WA the statement about advice must be written into the agreement, and the lawyer's certificate must be in an annexure to it. The same advice can be given, but an agreement that is put together the federal way may not meet the WA structure.

There is only one original

In WA one party keeps the original and the other keeps a copy. An agreement signed the federal way, with each lawyer holding a signed original, does not follow this step.

There is no rescue provision

The federal Act has a safety net. A court can declare an agreement binding even though some of the advice formalities were not met, if it would be unjust and inequitable for it not to be binding (s 90G(1A)). The WA Act has no equivalent. If a WA de facto agreement misses a formality, it is not binding, and the court can then divide the property as if there were no agreement.

That is why each party's lawyer matters so much. The lawyers are not only explaining the deal. They are each certifying a step the agreement depends on.

Setting an agreement aside

Even a properly made agreement can be set aside on the grounds in s 205ZV. These include:

(a) fraud, including failing to disclose something material;

(b) the agreement being void, voidable or unenforceable, for example because of duress or undue influence;

(c) circumstances arising that make it impracticable to carry out;

(d) a material change relating to the care of a child that would cause hardship; and

(e) unconscionable conduct.

Full disclosure of each party's finances before signing is the best protection against a later challenge.

If you marry, or move

Two events can change the position.

(a) If a de facto couple later marries, the federal Act then governs any property claim between them as a married couple. The WA Act does not say what happens to a WA de facto agreement on marriage, and we are not aware of a decided case on it. A common approach is to make a new agreement under the federal Act at the time of the marriage. Get advice before the wedding, not after.

(b) If a couple with a WA agreement moves to another state, the federal Act may treat the agreement as a federal de facto agreement from that point (s 90UE), and it is then enforced, varied or set aside under federal law.

Tax and duty

A transfer of property made under a financial agreement that complies with s 205ZS(1) can qualify for the capital gains tax rollover for relationship breakdowns (Income Tax Assessment Act 1997 (Cth) s 126-5). The Australian Taxation Office names the WA section expressly. An informal, private division does not qualify.

In WA, a transfer of property between the former partners under a qualifying agreement attracts no duty, or only $20 nominal duty, if the conditions in the Duties Act 2008 (WA) are met (ss 113, 131).

Getting it right

A financial agreement is a document that may sit in a drawer for twenty years before anyone tests it. For a WA de facto couple, the cost of a missed formality is the whole agreement. The safest course is for each of you to have your own WA family lawyer, for the agreement to be drafted for Part 5A from the start, and for the signing and the original to be handled exactly as s 205ZS requires.

This article is general information about the law in Western Australia as at 27 October 2026. It is not legal advice about your situation.