Understanding postnuptial agreements

Many people are familiar with the idea of a prenuptial agreement: a contract couples sign before marriage to determine how their assets will be divided if they separate. But what about agreements made after the wedding? That’s where postnuptial agreements (or “post nups”) come in.

A post prenuptial agreement, sometimes called a post marriage agreement or post nup, is a legal document couples enter into after marriage to clarify how finances, property and assets will be divided in the event of separation or divorce. .

In Australia, these agreements fall under the category of Binding Financial Agreements (BFAs), regulated by the Family Law Act 1975 (Cth). While they can provide clarity and security, they must be drafted carefully to be enforceable. A family lawyer who works with BFAs regularly can explain whether a post nup is appropriate for your situation or whether another structure would offer better protection.

Here are six important things you need to know about postnuptial agreements.

1. What is a postnuptial agreement?

A postnup is a written legal contract entered into by spouses after marriage. It typically addresses:

• How assets and debts will be divided if the marriage ends.
• Provisions for spousal maintenance.
• Financial arrangements during the marriage (in some cases).

Example: A couple marries without a prenup. Five years later, they buy a business together. They decide to draft a post marriage agreement to protect each spouse’s interests in case the marriage breaks down. In this scenario, the post nup provides clarity on how assets would be divided, reducing the risk of dispute later. 

2. Why would couples sign a post marriage agreement?

There are several reasons couples may decide to enter into a postnuptial agreement:

• Significant financial changes: One partner inherits money, acquires property or starts a business.
• Second marriages: To protect assets for children from previous relationships.
• Debt protection: Ensuring one partner is not responsible for the other’s debts.
• Strengthening the marriage: Sometimes used as a tool to provide financial clarity during reconciliation after relationship difficulties.
• Missed prenuptial opportunity: Couples who didn’t sign a prenup before the wedding can use a postnup instead.

Example: A woman receives a large inheritance after marriage. To protect the inheritance, the couple signs a postnuptial agreement outlining that the inheritance remains her separate property.

3. Legal requirements for a postnuptial agreement in Australia

In Australia, postnuptial agreements fall under the same legal framework as prenuptial agreements. This means they must meet strict legal requirements to be enforceable. To be valid under Australian law, a postnup must meet strict conditions:

• Independent legal advice: Each spouse must receive independent legal advice from a qualified family lawyer.
• Written and signed: The agreement must be in writing and signed by both parties.
• Lawyer’s certificates: Each lawyer must sign a certificate confirming they provided advice.
• Voluntary consent: Both parties must enter the agreement freely, without pressure, coercion or fraud.
• Full disclosure: All assets, liabilities and income must be disclosed honestly.
• No unconscionable conduct: The agreement must not be affected by factors such as duress, fraud, unconscionable conduct or material non-disclosure, as these can give the court grounds to set it aside. 

Key point: If these requirements are not met, the court can declare the postnup invalid. Courts can also set aside a postnuptial agreement in limited situations, for example if there was fraud, major non-disclosure or if caring responsibilities for children change in a way that makes the agreement clearly unfair.

Because of these risks, it is sensible to work with an experienced family lawyer who understands how courts have treated Binding Financial Agreements in past cases. Bark can help you compare family lawyers across Australia and request quotes before you commit.

4. Benefits of a post nup

• Financial certainty: Both parties know where they stand if the relationship ends.
• Asset protection: Safeguards inheritances, businesses and family wealth.
• Reduces conflict: Helps avoid lengthy, expensive court battles in the event of separation.
• Flexibility: Can be tailored to the couple’s specific circumstances.

Example: A couple who own investment properties together uses a post marriage agreement to outline how rental income and mortgage obligations will be divided if they separate. This prevents disputes later.

A well drafted post nup can also reduce the emotional temperature during separation, because both partners already know what to expect financially.

5. Risks and limitations of postnuptial agreements

While useful, postnups also come with risks:

• Possibility of being overturned: Courts can set aside a postnup if there was pressure, unfairness or lack of disclosure. They may also intervene if circumstances have changed so significantly, particularly around children, that enforcing the agreement would cause serious hardship.
• Relationship strain: Negotiating a financial agreement after marriage may cause emotional tension.
• Not a replacement for good communication: A postnup addresses finances but cannot guarantee harmony in the relationship.
• Ongoing legal costs: Drafting a valid postnup requires independent legal advice, which adds to costs.

Example: A husband pressures his wife to sign a postnuptial agreement just before he invests in a business. If she later challenges it, the court may declare the agreement invalid due to duress.

6. How family lawyers can help with postnuptial agreements

Because post marriage agreements must meet strict legal requirements, engaging an experienced family lawyer is essential. A lawyer can:

• Provide advice on your rights and obligations.
• Ensure the agreement is fair, enforceable and tailored to your situation.
• Prevent future disputes by drafting precise clauses.
• Represent you if the agreement is challenged in court.

Tip: Always seek independent legal advice as it protects both you and your spouse, ensuring the agreement stands up in court.

If you are considering a post marriage agreement but are unsure how to raise it with your partner, many family lawyers offer initial consultations where you can explore options and likely outcomes before deciding whether to proceed. You can use Bark to find family lawyers in Australia  who specialise in Binding Financial Agreements and compare their approach and pricing.

Conclusion: Navigating postnuptial agreements 

For many people, a postnuptial agreement (postnup) offers peace of mind, financial security and clarity in marriage. While not romantic, these agreements can be practical tools that protect both partners and reduce conflict if separation occurs.

If you’re considering a post marriage agreement, it’s essential to get independent legal advice. With Bark, you can connect with experienced family lawyers who can guide you through the process and ensure your postnup is fair, enforceable, and tailored to your unique circumstances.

Taking this step does not mean you expect the relationship to end; it simply means you are planning ahead so that both partners are protected if the unexpected happens.