Post-Nuptial Financial Agreement | s.90C Family Law Act

A financial agreement made after a marriage has already taken place is signed under section 90C of the Family Law Act 1975 (Cth), while one made after separation but before or without divorce falls under section 90D. For couples in a de facto relationship, the mirror provision is section 90UD within Part VIIIAB. People loosely call all of these a "post-nup", but the section you rely on changes depending on your relationship status and timing, and getting that wrong is one of the fastest ways to render the document vulnerable.

The distinction that matters most is between a financial agreement and consent orders. A financial agreement is a private contract between the two of you: no judge reads it, no court seals it, and its strength comes entirely from strict statutory compliance. Consent orders, by contrast, are filed with the Federal Circuit and Family Court of Australia and approved by a registrar, which makes them enforceable like any court order but also subjects them to the court's "just and equitable" scrutiny. A post-nuptial agreement trades that judicial safety net for privacy and control. You decide the outcome yourselves, which is exactly why the law insists each party walks in with their own solicitor. If protecting a business sits at the centre of your planning, it often pairs naturally with the way owners structure control through a shareholders agreement for a Pty Ltd company.

Everything begins with the Family Law Act 1975 (Cth). A financial agreement made during a marriage sits under section 90C, one made after separation under section 90D, and the de facto equivalents under sections 90UD and 90UE in Part VIIIAB. Whichever provision applies, the agreement only becomes binding if it satisfies the technical checklist in section 90G (marriages) or section 90UJ (de facto relationships). Those sections are not aspirational. Strict compliance is mandatory, and the courts have set aside agreements over deficiencies that looked minor on paper.

The central requirement is independent legal advice. Before signing, each party must receive advice from a separate legal practitioner about the effect of the agreement on their rights and about the advantages and disadvantages of signing at the time the advice is given. Husband and wife cannot share the same solicitor, and a de facto couple cannot lean on one adviser between them. Each lawyer then provides a signed statement of independent legal advice, often called a solicitor's certificate, and a copy is exchanged with the other side. The Full Court has made clear that this advice must be tailored to your actual asset pool and contribution history, referencing the section 75(2) factors and each party's likely entitlement under section 79. Template letters do not satisfy the section.

There is a discretionary safety valve. Under sections 90G(1A) and 90UJ(1A), a court may still declare an agreement binding despite a technical defect if it would be unjust or inequitable not to, a power the courts have used sparingly in cases such as Connery & Sims [2025]. Do not build a strategy around it. The court can also set an agreement aside entirely under section 90K or section 90UM, most commonly for fraud, material non-disclosure, or where circumstances relating to a child cause hardship. Since the Family Law Amendment Act 2024 commenced on 10 June 2025, the duty of financial disclosure now lives in the Act itself rather than the court rules, so hiding an asset is riskier than ever. The Federal Circuit and Family Court of Australia publishes the full list of formal requirements in its official guidance on financial agreements.

The most common driver is an inheritance or an expected gift that one party wants to keep separate from the shared pool. Australian courts treat inheritances as a contribution rather than an automatic exclusion, so a couple who assume "it's mine because grandma left it to me" are often surprised. A post-nuptial agreement records the intention clearly while both partners are still on good terms, which is worth far more than an argument about it years later. The next frequent scenario is the family business or professional practice. Owners who bring a company into a marriage, or build one during it, use these agreements to ring-fence equity and protect co-owners who never signed up to a family law dispute landing on the boardroom table.

Second marriages sit close behind. When one or both partners have children from an earlier relationship, a financial agreement can protect an estate plan so that assets flow to those children rather than being absorbed into a fresh property division. It works alongside, not instead of, a properly drafted Australian will under the Succession Act. De facto couples reach the same crossroads, often when buying property together or merging finances after years apart. De facto partners should not assume they have less to protect than married couples; Part VIIIAB gives them substantially the same rights, and the same 2025 reforms apply to them. One edge case worth flagging is the couple reconciling after a separation, where an earlier separation-stage agreement needs to be formally terminated before a new one can operate cleanly.

• The identification of the parties and relationship status fixes which head of power applies, whether section 90C for a current marriage or section 90UD for a de facto relationship. This single choice determines which binding requirements govern the agreement, so the template pins it down before anything else.
• The full asset, liability and superannuation schedule captures the property pool at the date of signing. Since the disclosure duty moved into the Family Law Act 1975 on 10 June 2025, an incomplete schedule is now a direct statutory breach, not merely a procedural slip, and it is a favourite ground for a later challenge under section 90K.
• The quarantining and division clauses set out exactly what stays separate (the inheritance, the business, the pre-relationship home) and how any shared property is split if the relationship ends. Vague drafting here is where most agreements come undone, so each item is described specifically rather than in general terms.
• The spousal or de facto maintenance provisions state whether either party gives up the right to seek maintenance, which the agreement can validly exclude if the drafting meets the statutory threshold. This is a powerful clause and one the template flags for close attention during your legal advice.
• The independent legal advice certificates annexe the signed statement from each party's solicitor confirming the s.90G or s.90UJ advice was given. Without these, the agreement is not binding, and the template is built around their inclusion rather than treating them as an afterthought.

Family law in Australia is federal, so the Family Law Act 1975 (Cth) governs financial agreements uniformly across every state and territory, which is a rare simplification in a country where most legal documents change at the border. New South Wales, Victoria and Queensland couples all sign under the same Part VIIIA and Part VIIIAB provisions, and the Federal Circuit and Family Court of Australia hears any resulting dispute regardless of postcode. What varies is the surrounding machinery. Western Australia runs its own Family Court of Western Australia, and for de facto couples in that state the agreements operate under the Family Court Act 1997 (WA) rather than the Commonwealth Part VIIIAB, a distinction that trips up couples who move west assuming their federal agreement automatically transposes.

Stamp duty and property transfer treatment also differ by state revenue office when an agreement moves real estate between partners, so a clause transferring a home in Queensland carries different duty consequences from the same transfer in South Australia. Superannuation splitting, by contrast, follows a single national regime, though the 2025 removal of certain separation declaration requirements for larger super interests applies everywhere. If your agreement deals with jointly held real property, it interacts with how ownership is recorded, and reviewing the practical handover often runs parallel to the sort of arrangements set out in a separation agreement under the Family Law Act. Couples with children frequently pair the financial agreement with a section 63C parenting plan so the money and the care arrangements are settled in one sitting.

You begin by confirming your relationship status, because that selects the correct statutory pathway between a marriage agreement and a de facto one, and the template adjusts its clause references accordingly. From there you build the asset schedule, listing every property, account, superannuation interest, business holding and liability in the names of both parties, since the disclosure obligation now sits inside the Family Law Act 1975 and demands nothing less. The form then walks you through what you want to quarantine and how any shared property should be divided, prompting you to describe each item specifically rather than in loose language that a court could later read against you.

Once the substance is drafted, the template generates the framework for the two independent legal advice certificates. This is the step you cannot shortcut. Each party must take the draft to a separate solicitor, receive tailored advice, and obtain a signed statement before the agreement is executed. The document is delivered in Word and PDF so you can refine wording during negotiation, then finalise a clean copy for signing and for your solicitors to certify. Business owners often review the finished agreement against their company constitution under s.136 of the Corporations Act to make sure nothing conflicts.

The single most damaging error is treating the independent legal advice as a formality. Couples who use one lawyer between them, or who sign first and seek advice later, hand the other side a ready-made ground to set the agreement aside. The advice must be genuinely independent, given before signing, and tailored to your real financial position rather than delivered from a template letter, because the Full Court has made plain that generic advice does not satisfy section 90G. Almost as common is incomplete disclosure. Leaving a superannuation interest or a business valuation off the schedule feels harmless when the relationship is happy, yet since 10 June 2025 it breaches a statutory duty and invites a challenge for material non-disclosure under section 90K.

People also assume the agreement is permanent once signed. It can be set aside where there has been fraud, unconscionable conduct, or a material change relating to a child that causes hardship, so an agreement drafted a decade ago may no longer reflect reality. Relying on an old agreement without reviewing it after a major life change is a genuine risk. Others forget that third parties are not bound by private agreements: a bank does not release you from a joint mortgage just because your document says one name comes off the loan, and refinancing needs its own process. Finally, some couples try to shorten or waive the statutory requirements in the drafting itself, which achieves nothing, because the Family Law Act 1975 sets the floor and no clause can lower it.