Binding Financial Agreements (Prenups) in Australia (2026)
A Binding Financial Agreement (BFA) is a private contract, made under the Family Law Act 1975, that decides how you and your partner will divide property and money if you separate, and when it is done properly it stops the court from making its own property orders.
In Australia, a prenup is simply a BFA signed before marriage or before you move in together. The same document can also be signed during the relationship (often called a postnup) or after you separate (often called a separation agreement). All three are the same legal creature with different timing. We advise on what a BFA is, what makes it legally binding, how it compares with consent orders, when it is the right tool, and the specific grounds on which a court can overturn one. We act for couples thinking about a prenup, people who have been handed one to sign, and anyone who signed one years ago and now wonders whether it will hold.
Key Takeaways
5 pointsA BFA can be made before, during or after a marriage (ss 90B, 90C, 90D) or a de facto relationship (ss 90UB, 90UC, 90UD). It is never filed with or approved by a court.
It only binds if both of you received independent legal advice and each lawyer signed a statement saying so (s 90G). Small paperwork failures have sunk agreements, although s 90G(1A) can now rescue some.
Unlike consent orders, a BFA does not have to be fair. A court will not undo it just because it turned out to be a bad bargain.
A court can set a BFA aside under s 90K for fraud or hidden assets, undue influence or unconscionable conduct, impracticability, a material change involving children, or because it is void or uncertain.
The High Court in Thorne v Kennedy [2017] HCA 49 showed that a prenup signed under wedding-eve pressure can fall even when the weaker party had a lawyer.
What Is a Binding Financial Agreement (Prenup)?
A Binding Financial Agreement is a written contract between current, future or former partners that sets out how your property, financial resources and spousal maintenance will be dealt with if the relationship ends, and it takes the place of a court decision on those issues.
The legal name in the Family Law Act is simply a financial agreement. People add the word binding because that is the whole point: once it meets the requirements, section 71A says the court's usual power to divide property no longer applies to the matters it covers. For de facto couples, section 90SA does the same job.
The Act sorts these agreements by when they are signed. The label matters because each agreement must say which section it is made under. In Balzia & Covich [2009] FamCA 1357, an agreement drafted under s 90B as a prenup was signed the day after the wedding, when s 90C should have been used, and the court declared it was not a valid financial agreement.
- s 90BDe facto couples s 90UB
Prenup, prenuptial agreement
Before marriage or before living together
- s 90CDe facto couples s 90UC
Postnup, postnuptial agreement, separation agreement
During the relationship (together or separated)
- s 90DDe facto couples s 90UD
Separation agreement, BFA after separation
After divorce or after the de facto relationship ends
A BFA can deal with:
- Property you own now, property you will acquire later, and debts
- Superannuation, including splitting it
- Spousal or de facto partner maintenance, as long as the agreement names who receives it and how much (s 90E), or releases it properly (s 90F)
- Specific assets you want to quarantine, such as a business, an inheritance or a home owned before the relationship
A BFA cannot decide where your children live or how much time they spend with each parent. Parenting arrangements are made through a parenting plan or parenting orders, and child support has its own system.
So are prenups legally binding in Australia? Yes, and since 2000 they have been part of the Family Law Act. But a prenup is only as strong as the way it was made. The next section explains the formal requirements that decide whether yours is binding at all.
What Makes a BFA Legally Binding?
A BFA is binding only if it is in writing, signed by both of you, signed after each of you received independent legal advice about its effect and its advantages and disadvantages, and each lawyer gave a signed statement of that advice which was also passed to the other side (s 90G).
Section 90G is a checklist, and the courts treat it seriously. The Full Court in Senior & Anderson [2011] FamCAFC 129 confirmed that compliance is mandatory. For an agreement made today, you need:
A written agreement signed by both parties
s 90G(1)(a)
Independent legal advice to each party, before signing, about how the agreement affects your rights and its advantages and disadvantages to you at that time
s 90G(1)(b)
A signed statement from each lawyer confirming that advice was given
s 90G(1)(c)
A copy of each lawyer's statement given to the other party or their lawyer
s 90G(1)(ca)
The agreement has not been terminated or set aside
s 90G(1)(d)
For married couples, the property terms of a BFA do not take effect until one of you signs a separation declaration after you separate, unless you have already divorced (s 90DA). For de facto couples the equivalent rules sit in ss 90UF and 90UJ.
Small gaps have had big consequences.
In Black [2008] FamCAFC 7 the Full Court set an agreement aside because it lacked a statement acknowledging the legal advice that the law then required. In Fevia & Carmel-Fevia [2009] FamCA 816 a prenup failed because the schedule listing the husband's assets was not attached when the wife signed.
Parliament responded in 2010 with s 90G(1A).
It lets a court declare an agreement binding despite defects in the advice or the statements, if it would be unjust and inequitable not to. Dragomirov [2024] FedCFamC1A 187 shows how this works. The wife's lawyer gave her only an outline of the law and did not explain what she was giving up, so the appeal court found the advice requirement was not met. But the agreement gave her about $28,000 less than half of a $1,433,083 pool, and the court upheld it under s 90G(1A).
What this means for you
Proof also matters. In Hoult [2013] FamCAFC 109 the Full Court held that a signed lawyer's statement is good first evidence that the advice was given, and the person attacking the agreement must produce evidence that throws it into doubt.
For the full breakdown of each requirement and how the rescue provision is applied, read Is Your Binding Financial Agreement Actually Binding?.
Binding Financial Agreement vs Consent Orders: What Is the Difference?
Consent orders are court orders that a registrar approves only if the division is just and equitable, while a BFA is a private contract that no court reviews and that does not need to be fair.
Both tools let you settle property without a trial. Both can split superannuation and deal with spousal maintenance. The differences are in timing, scrutiny, cost and how each can later be undone.
| Binding Financial Agreement | Consent Orders | |
|---|---|---|
| When you can make it | Before, during or after the relationship | Only after separation |
| Does it go to court? | No. It is never filed or approved | Yes. You file an application and the court reviews it |
| Fairness test | None. A lopsided deal can stand | Court must be satisfied it is just and equitable (s 79(2)) |
| Legal advice | Compulsory for both parties, with signed statements (s 90G) | Not compulsory, though strongly recommended |
| Typical cost | Usually higher: two lawyers, drafting and advice | Usually lower: court filing fee (currently $215) plus legal help if you use it |
| Privacy | Fully private document | Filed with the court and kept on the court record |
| Time limit to make it | No deadline in the Act | Within 12 months of divorce, or 2 years after a de facto separation (s 44), unless the court grants leave |
| How it can be overturned | s 90K grounds, plus contract law (s 90KA) | s 79A: miscarriage of justice by fraud, duress or non-disclosure, impracticability, default, or exceptional circumstances relating to a child |
| Covers future property | Yes | No, only what exists at the time |
Two practical points stand out.
What this means for you
First, the fairness gap cuts both ways. If you are the financially stronger party, a BFA can protect assets a court might otherwise share. If you are the weaker party, you can lock yourself into a result well below what the court would order. To see what courts actually order without an agreement, compare what property settlement percentages Australian courts order and real divorce property settlement case examples.
Second, a BFA can be harder to rely on than people think. Because no judge checks it at the start, disputes about whether it is valid usually surface years later, at separation. Consent orders are tested when they are made. The child-related ground is also easier to use against a BFA: s 90K needs only a material change, while s 79A needs circumstances of an exceptional nature. The Full Court noted this lower threshold in Fewster & Drake [2016] FamCAFC 214.
So, does a BFA need to go to court? No. That is its main appeal, and its main risk.
When Is a Financial Agreement the Right Choice?
A financial agreement works best when it has a clear, limited purpose that makes sense to both of you, such as protecting specific assets for children of a previous relationship, and it is riskiest when used to quarantine everything one partner owns from a partner who may later depend on them.
The Family Law Book, a leading practitioner text, identifies three situations where a BFA is most likely to be appropriate and to hold up:
Mutual quarantine. You both have assets from before the relationship, often for children from earlier marriages, and you each agree to keep them out of any future claim.
Limited unilateral quarantine. One of you protects a specific special asset, such as a family business, farm or inheritance, and everything else is left for the normal process.
Release of spousal maintenance after separation. You agree to a property division in exchange for a clean break from future maintenance claims.
A fourth model, keeping existing assets separate while sharing everything acquired later, was upheld in Cording & Oster [2010] FamCA 511. That couple had no children and signed late in the relationship, which helped.
A BFA tends to be the wrong tool when:
You plan to have children. The birth of a child and a parent stepping back from work is the classic material change that lets a court set an agreement aside under s 90K(1)(d).
You are the financially weaker party with no children planned. If your health or job fails, there is no hardship escape route without children, and the agreement can bind you to a poor result.
It is being drafted days before the wedding. Last-minute agreements invite claims of undue influence.
Neither of you has significant assets. The cost and complexity usually outweigh the benefit, and consent orders after separation are simpler.
It quarantines everything for one partner. The wider and more one-sided the agreement, the more likely it is to be attacked.
Some people use a family trust instead of, or alongside, a BFA. Trusts do not automatically protect assets in a separation, so read Does a Family Trust Protect Assets in a Divorce in Australia? before relying on one. If your main concern is an inheritance, our guide on how courts treat inheritance in divorce explains what happens without an agreement. And if you have already separated and simply want to formalise a deal, consent orders are often cheaper and safer, provided you file within the time limits for property claims after separation.
Can a Binding Financial Agreement Be Overturned?
Yes, but only on the specific grounds listed in section 90K of the Family Law Act, and regret or a bad outcome is never enough on its own.
This is the most important thing to understand about BFAs. The court has no general power to rewrite one because it seems unfair. In Dragomirov [2024] FedCFamC1A 187 at [49], Campton J put it simply:
Parties are perfectly free to enter into a bad bargain by way of a financial agreement.
The grounds in s 90K(1) (and s 90UM for de facto couples) are:
| Ground | Section | What it means in practice |
|---|---|---|
| Fraud, including non-disclosure of a material matter | s 90K(1)(a) | Your partner hid assets or lied about their finances to get you to sign |
| Defeating creditors | s 90K(1)(aa) | The agreement was made to defeat or recklessly disregard creditors |
| Void, voidable or unenforceable | s 90K(1)(b) | Contract law problems: duress, undue influence, mistake, uncertainty |
| Impracticability | s 90K(1)(c) | Something has happened since signing that makes it impracticable to carry out |
| Material change relating to a child | s 90K(1)(d) | A change in a child's care, welfare or development causes hardship |
| Unconscionable conduct | s 90K(1)(e) | One party took unfair advantage of the other's special disadvantage when it was made |
| Superannuation problems | s 90K(1)(f), (g) | A payment flag will not be lifted, or a super interest cannot be split |
Separate from s 90K, an agreement may simply not be binding because it failed the s 90G formalities discussed above. In practice, challenges are often run on both tracks at once: the agreement was never binding, and even if it was, it should be set aside.
Section 90KA adds that questions of validity are decided under the ordinary law of contract. That is how drafting problems come in. In Kostres [2009] FamCAFC 222 the Full Court found clauses about future assets so ambiguous that they could not be enforced.
The burden is on the person challenging the agreement, and these cases are expensive. For a full walkthrough of each ground with recent decisions, see When Can a Financial Agreement Be Set Aside in Australia?. The next two sections cover the grounds that come up most often.
Hidden Assets, Pressure and Unconscionable Conduct
The most common successful challenges involve what happened when the agreement was signed: one partner hid assets, or pressured or took advantage of the other, and these grounds can succeed even where the weaker party had independent legal advice.
Fraud and non-disclosure
Fraud means knowingly or recklessly making a false statement to get an unfair advantage, and it is hard to prove, as Wallace & Stelzer [2011] FamCA 54 shows. Non-disclosure is often easier. In Adame [2014] FCCA 42 the husband told his own lawyer to leave a Californian property out of the asset schedule because his wife did not know about it. Judge Jarrett found the agreement voidable at the wife's election, and also found she had signed under duress. If you suspect your partner understated their wealth, our article on what to do when a spouse hides assets explains how disclosure is forced in court.
Case: Wallace & Stelzer [2011] FamCA 54
Case: Adame [2014] FCCA 42
Undue influence and unconscionable conduct
The leading case is Thorne v Kennedy [2017] HCA 49. Ms Thorne was 36, had no substantial assets and had moved to Australia to marry Mr Kennedy, a 67-year-old property developer with assets of $18 million to $24 million. She signed the prenup four days before the wedding. It gave her nothing if they separated within three years, and a lump sum of $50,000 after that. Her own lawyer advised her strongly not to sign. She signed anyway, then signed a near-identical postnup after the wedding.
The High Court set both agreements aside for undue influence and unconscionable conduct. The majority listed factors that can matter for prenups and postnups:
- Whether the agreement was offered on a take-it-or-leave-it basis
- The emotional circumstances, including any threat to call off the wedding or end the relationship
- Whether there was time for careful reflection
- The nature of the relationship
- The relative financial positions of the parties
- The independent advice received, and whether there was time to reflect on it
The key lesson: independent legal advice does not guarantee a prenup will stand. If you signed against your lawyer's advice because you felt you had no real choice, that can count against the agreement.
Unconscionable conduct comes from Commercial Bank of Australia v Amadio [1983] HCA 14: one party has a special disadvantage, the other knows of it and takes unfair advantage. Similar pressure appears in Jacobs & Vale [2008] FMCAfam 641, where a husband said he signed during a 30-minute lunch-break meeting, five days before the wedding, after being told there would be no wedding otherwise. The court only decided that his challenge was arguable enough to go ahead, not that it would win, but the facts show the pattern courts look for.
For a full explanation of s 90K(1)(e) and how it differs from a simple bad deal, read Can a Binding Financial Agreement Be Overturned in Australia?.
Changed Circumstances: Children, Impracticability and Falling Asset Values
Life changing after you sign is generally not a ground to overturn a BFA, with two exceptions: the agreement has become impracticable to carry out, or a material change involving a child would cause hardship if the agreement stood.
Children (s 90K(1)(d))
This ground is designed to protect children and the parent caring for them. The usual example is a couple who sign before children, then one parent leaves work to raise them. But the hardship must come from the change itself. In Fewster & Drake [2016] FamCAFC 214 the wife was pregnant when the agreement was signed in 2006, and a second child followed in 2009. The trial judge set the agreement aside, but the Full Court allowed the husband's appeal because the hardship had to flow from the change in circumstances relating to the children, not from some other cause such as the terms of the agreement.
Impracticability (s 90K(1)(c))
This works like the contract doctrine of frustration. It covers events no one could reasonably foresee that make the agreement impracticable to carry out, not ordinary ups and downs. In La Rocca [1991] FamCA 97, a case on the same wording for court orders, a downturn that reduced a business's value was not enough. By contrast, in Herold & Kay [2012] FMCAfam 1071 an agreement was held unenforceable for impracticability when a party was unable to refinance a home mortgage.
Case: La Rocca [1991] FamCA 97
Falling asset values
In Sanger [2011] FamCAFC 210 the husband agreed to pay the wife $350,000. A company valued at $400,000 later went into liquidation and the former home, agreed at $750,000, sold for $649,000, so he ended up with far less than the 40 per cent he expected. The Full Court still held him to the agreement, saying:
As is not in doubt, the provisions of s 90K are not designed to, and do not facilitate a party escaping from what proves, or is perceived to be a "bad bargain".
If the value of assets in your BFA has dropped sharply, read Can Asset Depreciation Overturn a BFA in Australia? for when a value change can and cannot help you. If a business is involved, our guide on capital gains tax in divorce is also worth reading, since transfers under a BFA can carry tax consequences.
What Happens If a BFA Is Set Aside, or a Partner Dies?
If a BFA is set aside or found not binding, the court decides your property settlement under the normal rules in section 79 as if the agreement never existed, and if a partner dies, a valid BFA binds their estate.
Once an agreement falls away, you are back in the standard process. The court identifies the asset pool, assesses each person's contributions, looks at future needs, and checks that the result is just and equitable. Our guide to how Australian courts divide property walks through those steps. When it sets an agreement aside, the court can also make orders, including property transfers, to adjust the parties' rights (s 90K(3)).
That outcome can be very different from what the agreement said, and the 70/30 and other percentage splits courts order give you a sense of the range. Timing matters too: if your BFA was supposed to resolve everything and it fails, you may need the court's permission to bring a late property claim.
Some other rules people often miss:
s 90H
Death
A binding agreement continues after a party dies and binds their personal representative (s 90H, or s 90UK for de facto couples). Your will should be consistent with it. If a partner dies in the middle of a dispute, see what happens if a party dies during property settlement.
s 90J
Ending a BFA by agreement
You can cancel a BFA with a termination agreement, which needs the same legal advice and signed statements as the original (s 90J).
s 90L
Stamp duty
Transfers made under a BFA are exempt from state stamp duty (s 90L, or s 90WA for de facto couples).
s 90F
Spousal maintenance
A release of maintenance only works if the agreement records that the person giving it up could support themselves without an income-tested pension, allowance or benefit (s 90F). Without a valid release, a claim may still be possible, as explained in spousal maintenance claims after divorce.
How to Make a BFA That Holds Up, and What It Costs
A BFA that survives a challenge is one negotiated early, with full disclosure, a clear and limited purpose, separate lawyers for each of you, and time to reflect before signing.
Whether you are asking for a prenup or being asked to sign one, use this checklist:
Start months before the wedding or move-in date
Thorne v Kennedy and Jacobs & Vale both involved signing within days of the wedding.
Exchange full financial disclosure
List every asset, debt, trust interest, business and expected inheritance, and attach the schedules to the copy each person signs.
Use two separate law firms
Each of you needs your own lawyer, who advises you alone and signs the statement of advice.
Keep the purpose narrow and the drafting clear
Vague clauses about future assets failed in Kostres. A simple quarantine of named assets is easier to enforce.
Plan for children
Include a review or termination trigger if a child is born, because that is when agreements are most exposed.
Keep it negotiable
An agreement presented as non-negotiable is one of the Thorne v Kennedy warning signs.
Update it when life changes
A new child, a business sale or a large inheritance are all reasons to revisit it.
How much does a prenup cost in Australia? There is no set fee. Published pricing from Australian family law firms puts drafting a straightforward BFA at roughly $3,000 to $8,000, with larger firms and complex asset structures at the top of that range or above. The other party also pays their own lawyer for independent advice and a signed statement. Businesses, trusts, blended families and lengthy negotiations all push the price up. For comparison, a contested property case that runs to trial can cost each party far more. Consent orders are usually cheaper, with a court filing fee of $215 plus any legal fees.
Can you use a BFA template or DIY kit? You can start from a template, but you cannot finish one alone. A BFA is not binding unless both of you receive independent legal advice and signed lawyer statements, so there is no truly do-it-yourself version. Template wording also tends to fail on exactly the points courts examine: attached schedules, clear definitions, and properly drafted maintenance clauses.
If you were handed a prenup to sign, the most useful thing your lawyer can do is tell you plainly what you are giving up compared with what a court would likely order. If they advise against signing, take that seriously, and give yourself time to think it over.
Frequently Asked Questions
The basics
What is a prenup in Australia?
A prenup is a Binding Financial Agreement signed before marriage under s 90B of the Family Law Act, or before a de facto relationship under s 90UB. It sets out how property, super and maintenance will be divided if you separate, and if it meets the legal requirements, it replaces a court decision on those matters.
What does BFA mean?
BFA stands for Binding Financial Agreement. It is the everyday name for a financial agreement under Part VIIIA (married couples) or Part VIIIAB (de facto couples) of the Family Law Act, whether it is signed before, during or after the relationship.
Are prenups legally binding in Australia?
Yes, if they meet the requirements in s 90G: a signed written agreement, independent legal advice to each party, and signed statements from each lawyer exchanged between you. A prenup that meets those requirements can still be set aside on the limited grounds in s 90K, such as hidden assets or undue influence. See what makes a BFA binding under s 90G.
Timing and court
Can I make a BFA after separation?
Yes. Separated couples can make a BFA under s 90C (still married) or s 90D (after divorce), and de facto couples under s 90UC or s 90UD. Many separated couples choose consent orders instead, because a court checks they are fair and they are usually cheaper.
Does a BFA need to be registered with the court?
No. A BFA is a private contract that is never filed with, registered by or approved by the court. That keeps it private, but it also means nobody tests it until a dispute arises, often years later.
Challenges and cost
Can a binding financial agreement be overturned?
Yes, but only on the grounds in s 90K, including fraud or non-disclosure, undue influence, unconscionable conduct, impracticability, a material change involving a child that causes hardship, or the agreement being void or uncertain. A bad bargain on its own is not enough. Read our detailed guide to setting aside a financial agreement.
How much does a BFA cost?
Fees vary with complexity. Published pricing from Australian firms commonly falls between about $3,000 and $8,000 for drafting, plus a separate fee for the other party's independent advice. Agreements involving businesses, trusts or extended negotiation cost more.
Summary
A Binding Financial Agreement lets you decide your own property outcome instead of leaving it to a court, but it only protects you if it is made properly and fairly enough to survive scrutiny later.
What it is. A prenup, postnup or separation agreement is a financial agreement under ss 90B to 90D (or ss 90UB to 90UD for de facto couples). It replaces the court's power to divide the property it covers.
What makes it binding. Independent legal advice and signed lawyer statements under s 90G are essential. Section 90G(1A) can rescue some defective agreements, as in Dragomirov, but you should not plan to rely on it.
BFA vs consent orders. A BFA is private, flexible and can be made at any stage, but it has no fairness check and costs more. Consent orders are court-approved, cheaper and only available after separation.
When it fails. Courts set BFAs aside for hidden assets, pressure and unconscionable conduct (Thorne v Kennedy), impracticability, child-related hardship, and unclear drafting, but not for a bad bargain (Sanger).
Need professional legal help?
If you are considering a prenup, have been asked to sign one, or want to know whether an existing BFA will hold, get advice from a family lawyer who can compare the agreement with what a court would likely order in your situation.
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