πŸ’‘ Money & Relationships

What Is a Prenup in Australia? The Complete Guide

A prenup in Australia is legally called a binding financial agreement. What it covers, when courts can set it aside, and who actually needs one.

Timothy Hirou GaschereauBy Timothy Hirou GaschereauPublished

10 min read

⚠️ Before you read on

This article is general information only. It is not financial advice and not legal advice. Binding financial agreements are legally technical, and a badly drafted one can cause more problems than having no agreement at all. Nothing here creates a lawyer-client relationship. Always talk to a qualified family law solicitor before entering into any financial agreement.

"Prenup" is the word that gets searched. In Australia, the legal name is a binding financial agreement, or BFA, and it's governed by the Family Law Act 1975. This is part of a wider guide to money and relationships on Snowball Invest. Wondering what one actually costs? We've broken that down separately in how much a prenup costs in Australia.

Quick answer

A prenup in Australia is officially a binding financial agreement. It sets out how assets and liabilities get split if a relationship ends, and it can hold up in court, but only if it's drafted properly, both people get independent legal advice, and it's signed and certified the right way. A badly done one is genuinely worse than not having one.

In this guide

  • β†’What a binding financial agreement actually is
  • β†’When courts can, and can't, set one aside
  • β†’The difference between a prenup, postnup and separation agreement (there isn't much)
  • β†’What a BFA can and can't cover, children are always off the table
  • β†’Who genuinely benefits from getting one

πŸ“œ What is a prenup in Australia?

A binding financial agreement is a private contract between two people that sets out, in advance, how their assets and liabilities will be divided if the relationship breaks down. It can also cover spousal maintenance, whether one person will financially support the other after separation, and on what terms.

What a BFA can and can't cover
Can coverCannot cover
Property owned before the relationshipChild custody arrangements
Property acquired togetherChild support payments
Inheritances and gifts
Business interests
Superannuation
Spousal maintenance

Courts always keep jurisdiction over children, full stop. No private contract can override a child's right to appropriate financial support or care arrangements. Try to squeeze child-related terms into a BFA and those clauses simply won't be enforceable.

βš–οΈ Does it actually hold up in court?

🎯 The essential: Yes, if it meets the requirements in the Family Law Act 1975. The word "if" is doing a lot of work in that sentence.

For a BFA to be binding, it generally must be in writing, signed by both parties, and each party must have received independent legal advice from their own separate solicitor before signing, with a signed certificate confirming that advice was given and exchanged between the parties.

The independent legal advice requirement isn't negotiable. Each person engages their own lawyer, not the same one, and that lawyer has to actually advise them on the agreement's effect on their rights before they sign. A court can set an agreement aside where there was fraud (including failing to disclose assets), where the agreement is void, voidable or unenforceable under general legal principles (this is where undue influence or unconscionable conduct come in), where it's impracticable to carry out, or where circumstances relating to children have materially changed since signing in a way that would cause hardship if the agreement was enforced as written.

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A poorly drafted BFA can be worse than having none at all. Courts have set agreements aside over technical defects, like a defective legal advice certificate or inadequate advice. Cutting corners here isn't a saving, it's a risk.

πŸ—“οΈ Prenup, postnup, same thing

There's no real legal difference. "Prenup" just means a BFA made before marriage. The same type of agreement can be made at several points in a relationship, each with its own naming convention.

Before marriage

Prenup

During marriage

Postnup

After separation

Separation agreement

Same document, same legal requirements, different name depending on when it’s signed

A binding financial agreement made before marriage, during marriage, or after separation, it's the same legal document with the same requirements, just a different name.
When a binding financial agreement can be made
TimingCommon name
Before marriagePrenup
During marriagePostnup
After separation or divorceSeparation agreement
Before a de facto relationshipDe facto prenup
During a de facto relationshipDe facto postnup
After a de facto relationship endsDe facto separation agreement

De facto couples, including same-sex couples, have had access to binding financial agreements since 2009. The requirements for validity are essentially the same as for married couples. We cover the broader picture of de facto rights in de facto relationships and money.

πŸ’Ό What it can and can't cover, in more detail

  • Pre-relationship property: the home you already owned, an investment property, savings, can be ring-fenced so it stays yours.
  • Property acquired together: how jointly built-up assets get split.
  • Inheritances and gifts: money or property from family during the relationship, which can otherwise end up in the shared asset pool.
  • Business interests: your stake in a business, particularly important if a separation could otherwise destabilise it.
  • Superannuation: often one of the largest assets either person holds.

What it cannot touch: anything about children. Child support runs on separate legislation, and parenting arrangements are always subject to the court's oversight of what's in the child's best interests.

🎯 Who should actually consider one

A BFA isn't really about distrust. It's about clarity, having the honest money conversation before emotions run high. Strong candidates include people with a significant asset gap between partners, business owners, people with kids from a previous relationship, anyone expecting a meaningful inheritance, and people entering a second marriage with more assets and more complexity to protect.

Couples with minimal assets, no children from earlier relationships, and roughly equal financial positions probably don't need one, though that calculus shifts as wealth grows. Moneysmart notes that if you have assets you want to protect, like property or super, a binding financial agreement is worth considering. The key is going in with clear eyes about what it can and can't actually do.

🧭 How you actually get one

  1. Full disclosure. Both parties disclose all assets and liabilities, property, savings, super, debts, business interests, trusts, everything. Hiding assets is grounds for a court to set the agreement aside later.
  2. Separate solicitors. Each party engages their own independent family law solicitor.
  3. Drafting and review. Typically one side's solicitor drafts the agreement, the other reviews it and may negotiate changes.
  4. Advice and signing. Each solicitor advises their client, signs a certificate confirming it, and both parties sign the agreement itself.
  5. Safe storage. A BFA doesn't need to be filed with a court. Both parties keep a copy, and so does each solicitor.

Curious what all of this actually costs? See our full breakdown in how much a prenup costs in Australia.

🧐 Common myths, cleared up

Myth: signing a BFA means you expect the relationship to fail. Most family lawyers would push back on that framing. It's closer to buying insurance, you're not planning for disaster, you're just not leaving a major financial question entirely to chance.

Myth: a BFA is bulletproof once it's signed. Not quite. It's only as strong as the process behind it, correct legal advice, full and honest disclosure, and the right sections cited. A sloppy one can be picked apart in court just as easily as having no agreement at all.

Myth: you only need one if you're wealthy. Wealth raises the stakes, but it isn't the only reason people get one. Business owners, people supporting kids from an earlier relationship, and anyone who wants a clear-eyed conversation about money before things get serious all have reasons to consider it, regardless of the numbers involved.

Myth: once you're married, it's too late. It isn't. A postnup made during the marriage carries exactly the same legal weight as one made beforehand, provided it meets the same requirements.

πŸšͺ What happens without one

If there's no BFA, the Family Law Act 1975 applies by default when a relationship ends. The Federal Circuit and Family Court of Australia weighs each person's financial and non-financial contributions, future needs like age, health and care of children, and everything in the shared asset pool, including super.

There's no automatic 50/50 split, the court assesses what's just and equitable in the circumstances. But there's also no automatic protection for assets you brought into the relationship. A home you owned before you met your partner can become part of the shared pool, particularly in a long relationship. That's the exact gap a BFA is designed to fill.

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❓ Frequently asked questions

Can you write your own prenup in Australia?

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You can draft your own document, but it won't be a valid binding financial agreement. For it to be enforceable under the Family Law Act 1975, both people need independent legal advice from separate solicitors before signing, with signed certificates confirming it happened. Without that, the agreement isn't binding.

Does a prenup expire in Australia?

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There's no automatic expiry. It stays in force until it's replaced by a new agreement, formally terminated in writing by both parties, or set aside by a court. It can become vulnerable over time if circumstances change significantly, particularly around children.

Can a prenup be challenged in court?

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Yes. A court can set aside an agreement for reasons including fraud or non-disclosure of assets, the agreement being void, voidable or unenforceable at general law (which is where things like undue influence or unconscionable conduct come in), the agreement being impracticable to carry out, or a material change in circumstances relating to children that would cause hardship if the agreement stood. Courts don't set agreements aside just because one party later feels they got a bad deal, but they will act where the process was flawed.

Can you get a prenup after you're already married?

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Yes. An agreement made during a marriage is often called a postnup. It has the same requirements as one made before marriage, independent legal advice, a written agreement, and signed certificates from each solicitor.

Does a prenup cover superannuation?

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Yes. Super is treated as property under Australian family law, and it's often one of the largest assets either person holds, so a binding financial agreement can specify exactly how it's dealt with if the relationship ends.

Is getting a prenup just about not trusting your partner?

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Not really, most family lawyers describe it as practical rather than pessimistic. It's an honest conversation about money had upfront, while things are calm, instead of during a stressful separation. Plenty of couples find the process clarifying rather than awkward.

Do de facto couples need a different type of agreement?

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De facto couples use the same type of agreement, a binding financial agreement, just under different sections of the Family Law Act. The requirements for it to be valid are essentially identical, including mandatory independent legal advice for both people.

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Timothy Hirou Gaschereau

Timothy Hirou Gaschereau

Founder of Snowball Invest, not a financial adviser.

I write about what I'm learning myself, because nobody ever taught us how to take control of our own money. It's a skill, not a mystery, and it's never too late to learn it. The best day to start was yesterday, the second best is today.