In this guide(12 sections)
If you're about to move in together — or you already have, and one of you owns the home, a business or most of the savings — you may be wondering whether you need "something in writing". That's a sensible question, not an unromantic one. The good news: Australian law lets de facto couples agree in advance how their finances would be dealt with if they ever separated, and a well-made agreement gives you both certainty. Below is how cohabitation agreements work in plain English — and if any of it feels daunting, you don't have to work it out alone. Fill in the enquiry form and Elisa will call you back. The first 30 minutes are free.
At a glance — cohabitation agreements in Australia
| What it is | A Binding Financial Agreement (BFA) between de facto partners |
| The law | Part VIIIAB of the Family Law Act 1975 (Cth) |
| Before living together | s 90UB |
| During the relationship | s 90UC |
| After separating | s 90UD |
| When de facto property rights usually start | 2 years together, a child together, significant contributions, or a registered relationship (s 90SB) |
| What makes it binding | Signed by both, independent legal advice for each of you, and a signed statement of that advice (s 90UJ) |
| What it can cover | Property, superannuation, financial resources and spousal maintenance |
| What it can't cover | Parenting arrangements; child support needs a separate agreement |
| Can it be set aside? | Yes, on limited grounds (s 90UM) — such as non-disclosure, fraud or unconscionable conduct |
| Our fee | From $4,400 (straightforward); $6,600–$9,900 where there are business, trust or complex assets — confirmed in writing |
| Western Australia | Different legislation applies to WA de facto couples |
What is a cohabitation agreement?
A cohabitation agreement is the everyday name for a Binding Financial Agreement made by de facto partners under Part VIIIAB of the Family Law Act 1975 (Cth) — section 90UB before you start living together, section 90UC during the relationship, and section 90UD after it ends. It sets out how your property, superannuation and financial resources would be divided if you separated, and whether either of you would pay maintenance to the other.
Think of it as the de facto version of a prenup. Married couples (and couples planning to marry) make their agreements under different sections of the same Act; the rules are very similar. If you're planning a wedding, our guide to prenuptial agreements explains that path.
The first 30 minutes are free, with no obligation. Book a free consultation → · or speak to Eliana, our assistant, any time on 03 4328 5084 — she'll get your matter to Elisa quickly.
When do de facto property rights actually start?
Under section 90SB of the Family Law Act 1975, a court can generally only make property orders for a de facto couple if the relationship lasted at least two years in total, there is a child of the relationship, one partner made substantial contributions and serious injustice would result without an order, or the relationship was registered under a state or territory law. That's why many couples choose to put an agreement in place early — before the two-year mark arrives and the law's default rules begin to apply.
It's a common myth that nothing changes until you've lived together for two years. In reality, the "two years" is a total period and doesn't always need to be continuous, a child or a registered relationship can bring the rules in sooner, and the question of whether you were in a de facto relationship at all depends on the whole picture of your life together. Our guides on de facto property rights and how a de facto relationship is proved go into more detail.
Why would we need one?
A cohabitation agreement lets you decide your own arrangements in advance instead of leaving them to the court's discretion under the Family Law Act 1975. Couples most often want one when:
- One of you owns the home you'll be living in, or brings significantly more savings into the relationship
- There's a family business, a share in one, or a family trust
- One of you expects an inheritance or has family wealth to protect
- You've been through a separation before and want clarity this time
- You have children from an earlier relationship and want to protect what they'll inherit
- You're buying property together in unequal shares
Not every couple needs one. If you're starting out with similar assets and similar earnings, the free first call is a good place to work out whether an agreement is genuinely worth it for you.
What makes a cohabitation agreement legally binding?
Under section 90UJ of the Family Law Act 1975, a de facto financial agreement is binding only if it's signed by both of you, each of you received independent legal advice about its effect on your rights and its advantages and disadvantages before signing, and each of you was given a signed statement from your lawyer confirming that advice. These requirements are strict. If any of them is missed, the agreement may not bind you at all.
In practice, that means:
- Separate lawyers. One lawyer can't advise you both. Elisa acts for one of you; your partner engages their own lawyer.
- Full disclosure. Each of you sets out your assets, debts, income and super honestly. Leaving something out is one of the main reasons agreements fail.
- Real advice, not a rubber stamp. The advice must be genuine — what you're giving up, what you're protecting, and what could happen if circumstances change.
- Time to think. Nobody should be signing under pressure, such as the day before moving in or settlement on a shared home.
Want to know if your situation needs one? That's exactly what the free first call is for. Book a free 30-minute call → · or reach Eliana any time on 03 4328 5084
What can a cohabitation agreement cover — and what can't it?
A cohabitation agreement made under Part VIIIAB of the Family Law Act 1975 can deal with your property, superannuation, financial resources and spousal maintenance — but it can't decide arrangements for children. It can cover:
- Who keeps what — the home, investments, cars, savings
- How superannuation is treated, including whether it's split
- Assets acquired during the relationship, and how growth in value is shared
- Gifts and inheritances, and whether they're kept separate
- Whether either partner pays maintenance after separation
What it can't do: parenting arrangements are always decided according to the children's best interests, so they can't be locked in by a financial agreement. Child support needs a separate child support agreement. And a cohabitation agreement doesn't replace a will — if you're protecting assets for children or family, it's worth updating your wills at the same time.
When can a cohabitation agreement be set aside?
A court can set aside a de facto financial agreement only on the limited grounds in section 90UM of the Family Law Act 1975 — including fraud or non-disclosure of a material matter, the agreement being void, voidable or unenforceable, unconscionable conduct, circumstances making it impracticable to carry out, and a material change relating to the care of a child that would cause hardship. Duress and undue influence can also make an agreement voidable.
The protective steps are the same ones that make it binding in the first place: disclose everything, get genuine independent advice, give each other time, and build in sensible review points for big life changes such as having children.
What goes wrong with cohabitation agreements?
These are common situations where cohabitation agreements come apart — described generally, not as any particular client's matter:
The agreement signed on moving day. One partner is handed a document to sign the week the keys change hands. Even with a lawyer's certificate attached, an agreement signed under that kind of pressure is exposed to challenge.
The template from the internet. A couple downloads a "cohabitation agreement" and both sign it at the kitchen table. Without independent legal advice and signed statements, it doesn't meet section 90UJ and isn't binding.
The agreement that didn't grow with the family. It was made when there were no children. Years later, one partner has stepped back from work to raise them, and the agreement makes no provision for that — a material change relating to children is one of the grounds for setting it aside.
The investment property that wasn't listed. One partner leaves out an asset. When the relationship ends, the non-disclosure becomes the reason the whole agreement is challenged.
None of these mean agreements don't work. They mean the way an agreement is made matters as much as what it says.
How much does a cohabitation agreement cost?
At Fogarty Oliver Rothschild, a cohabitation agreement (a Binding Financial Agreement under Part VIIIAB of the Family Law Act 1975) starts from a fixed $4,400 for straightforward matters, and $6,600–$9,900 where there are business interests, trusts or complex assets. Your fee is confirmed in writing after a free 30-minute consultation, once it's clear what your situation needs, and before any work begins. Your partner's independent lawyer charges separately, because each of you must have your own advice.
Across the market, fees commonly range from a few thousand dollars per person for a simple agreement to considerably more where trusts, businesses or overseas assets are involved. For the full breakdown, see what a Binding Financial Agreement costs and our fixed-fee packages.
How we make it easy: (1) a free, unhurried first call · (2) your fee in writing · (3) Elisa drafts the agreement around what you both want to protect · (4) your partner gets their own independent advice · (5) you sign with time to spare — no pressure, no surprises.
What happens when you call us: Eliana takes a few details and passes them to Elisa, who calls you back. In that first conversation she'll ask about your relationship, what each of you owns and what you're hoping to protect, explain whether an agreement makes sense, and confirm the fee in writing if you decide to go ahead.
What if we later marry?
Couples who make a cohabitation agreement and later marry should have it reviewed, because married couples' agreements are dealt with under different sections of the Family Law Act 1975. Depending on how the agreement was drafted, it may need to be updated or replaced so it continues to work the way you both intend. It's a straightforward conversation to have before the wedding — and a good reason to start well ahead of the date.
Frequently asked questions
What is a cohabitation agreement in Australia?
It's a Binding Financial Agreement between de facto partners, made under Part VIIIAB of the Family Law Act 1975 (Cth) — section 90UB before you live together, section 90UC during the relationship, or section 90UD after separation. It sets out how property, super and finances would be dealt with if you separate.
Are cohabitation agreements legally binding in Australia?
Yes, if they meet the requirements of section 90UJ: signed by both of you, independent legal advice for each of you before signing, and a signed statement of that advice from each lawyer. An agreement without those steps may not be binding.
When do de facto property rights start?
Generally, under section 90SB, a court can make property orders if you've been together for at least two years in total, have a child together, one of you made substantial contributions and serious injustice would otherwise result, or your relationship was registered.
Can we use the same lawyer?
No. Each of you must receive independent legal advice from your own lawyer. Elisa acts for one partner only.
Can a cohabitation agreement cover our children?
No. Parenting arrangements are always decided according to the children's best interests, and child support needs a separate child support agreement. A cohabitation agreement covers property, superannuation and spousal maintenance.
How much does a cohabitation agreement cost?
At Fogarty Oliver Rothschild, from $4,400 for a straightforward agreement and $6,600–$9,900 where business, trust or complex assets are involved, confirmed in writing after a free 30-minute consultation. Your partner's lawyer charges separately.
Can a cohabitation agreement be overturned?
Only on limited grounds in section 90UM of the Family Law Act — such as non-disclosure, fraud, unconscionable conduct, impracticability, or a material change relating to children causing hardship. Full disclosure, independent advice and time to consider are what make an agreement hold.
Does this apply in Western Australia?
De facto financial agreements in Western Australia are made under separate state legislation. Elisa advises on agreements under the Family Law Act 1975 for couples elsewhere in Australia.
Feeling unsure? That's exactly what Elisa is here for
Wanting clarity before you share a home is a caring thing to do — for both of you. Elisa helps couples put fair, workable agreements in place, calmly and in plain language, with the fee agreed in writing up front.
The first 30 minutes are free.
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Written and reviewed by Elisa Rothschild BA/LLB — Principal Lawyer, Fogarty Oliver Rothschild. Admitted to legal practice in Victoria. Family and property law in Melbourne since 2012.Last reviewed 21 October 2026.
This guide is general information about Australian family law, not legal advice for your specific situation. For advice on your matter, book a free 30-minute consultation.