A binding financial agreement (BFA) can include a sunset clause, which ends the agreement or part of it on a set date or life event, but it only works when paired with a proper termination agreement.
Lifestyle clauses about behaviour and fidelity clauses that punish cheating can be written in, but there is no case law confirming a court would enforce them, so they carry real risk and rarely add reliable protection.
The gap between a clause that holds up and one that a court simply ignores comes down to what the clause is actually trying to do. Here is what each type can and cannot achieve under Australian law.
Can a BFA Include a Sunset Clause?
Yes, a BFA can include a sunset clause, and this is the one clause type on this list that courts will readily give effect to when it is drafted correctly.
A sunset clause is a term that makes the whole agreement, or a specific part of it, stop operating on a chosen date or when a certain event happens.
The most common trigger used in practice is the birth of a first child, at which point many couples want their financial arrangement to fall away so their new circumstances can be assessed afresh.
Once a sunset clause brings the agreement, or part of it, to an end, that part no longer shuts the court out of those matters, so the ordinary property and maintenance framework under the Family Law Act 1975 can apply again if the couple later separates.
What Does a Sunset Clause in a BFA Actually Do?
A sunset clause sets a clear end point so an agreement does not lock a couple into terms that no longer fit their lives.
Some couples use it to protect assets brought into a relationship for a set number of years only, with those protections stepping down over time or ending on a milestone.
Others use it as a full expiry date, after which the whole agreement lapses and both people are free to negotiate again or rely on the law.
This flexibility is one of the genuine strengths of a BFA over a court order, because the couple designs the timing rather than a judge imposing it.
Why a “Review Only” Sunset Clause Can Fail
A sunset clause that simply says the couple must “review” the agreement when an event occurs is not enforceable on its own, and this is a trap that catches poorly drafted agreements.
A promise to renegotiate in the future is too uncertain for a court to give effect to, because it does not actually decide anything.
To make a sunset clause work, the agreement usually has to be built as a combined document that includes a valid termination agreement, so the ending of the old terms is legally clean.
That means the same strict requirements apply, including independent legal advice for both people, which is why this kind of clause needs careful drafting rather than a template.
Can a BFA Include a Fidelity Clause?
You can write a fidelity clause into a BFA, but there is no case law confirming an Australian court would enforce one, and the prospects of it being upheld are poor.
A fidelity clause tries to impose a financial penalty on a partner who is unfaithful, often by shifting more of the property to the other person if cheating occurs.
This kind of clause works as a punishment for personal conduct, which sits outside the property, financial resource, and maintenance matters a BFA is built to decide, and it has been many years since fault of this sort was relevant to a family law property outcome.
The wider legal backdrop matters here too, because Australia has had no-fault divorce since the Family Law Act came into force in 1975, and the system deliberately moved away from blaming one partner for the end of a relationship.
Bringing fault back in through a private contract runs against that whole approach, and there is a further risk that a clause found to be invalid or too uncertain could give a court scope to set aside the wider agreement.
In practice, a couple who feels strongly about honesty is far better served by open conversation and, where relevant, by keeping certain assets clearly separated in the financial terms that a court will actually uphold.
Can a BFA Include Lifestyle Clauses?
Lifestyle clauses can be written into a BFA, but there is no case law confirming a court would enforce them, and they are generally seen as risky because they ask a court to weigh personal behaviour rather than divide property.
These are terms that try to control day-to-day conduct, such as appearance, weight, household chores, how often a couple socialises, or activity on social media.
A term that penalises a partner for gaining weight or skipping the housework is unlikely to be given effect, partly because judges may be reluctant to rule on private conduct that the Family Law Act does not require them to decide.
Pets are a special case worth understanding, because a “who keeps the dog” term is really about ownership of property rather than behaviour.
Australian law has long treated animals as property, and from 10 June 2025, the courts must weigh a specific list of factors when deciding disputes about companion animals and cannot order shared ownership.
A clearly drafted BFA can still record who owns and keeps a pet as part of the property settlement, which lets a couple avoid that court process entirely.
What Can a BFA Legally Cover?
A BFA is limited by statute to financial matters, and understanding those limits explains why some clauses hold and others do not.
Under the Family Law Act 1975, married couples can make an agreement before marriage, during the marriage, or after divorce, dealing with how property and financial resources are split and how spousal maintenance is handled.
Agreements for married couples can also cover matters that are incidental or ancillary to those financial issues, plus a category the Act calls “other matters,” although any “other matters” provision has no force or effect unless and until the marriage breaks down.
De facto couples have their own set of provisions, and importantly, their agreements can only add matters that are incidental or ancillary to the financial terms, not the broader “other matters” category open to married couples.
There is very little case law on how far these extra categories reach, which is a big part of why a lifestyle or fidelity clause has no settled place in the framework and no clear path to being enforced.
The table below compares the three clause types across the questions couples most often ask.
| Clause type | Can it be written into a BFA? | Likely to be enforced by a court? | What the law treats it as |
| Sunset clause | Yes, when paired with a valid termination agreement | Yes, if drafted correctly; a “review only” trigger is not | A valid way to end the agreement or part of it on a date or event |
| Fidelity clause | Yes, usually framed as a financial penalty for cheating | Untested; prospects poor | A penalty for conduct, outside the core property and maintenance matters |
| Lifestyle clause | Yes, though often purely behavioural | Untested; widely seen as risky | A personal or behavioural term with no settled place in the Act |
The pattern is clear once the framework is understood, because the clauses tied to money and to ending the agreement are the ones that carry legal force.
Behavioural and moral clauses can sit in the document, but they sit outside the part of the agreement a court can reliably act on.
Why Do Unenforceable Clauses Still Cause Problems?
Including a clause that a court will ignore is not harmless because it can create false confidence and invite disputes later.
A partner who signs believing a fidelity clause protects them may make life decisions on that basis, only to find the term collapses when it is tested.
There is also a drafting risk, since a badly worded or clearly invalid clause may need to be severed from the agreement, and any confusion it creates can become a foothold to have the agreement set aside.
The cleaner approach is to keep the financial core of the agreement precise and well drafted, and to leave out terms that add emotional weight but no legal substance.
That way, the property, maintenance, and any sunset arrangements stand on solid ground, rather than being tangled up with clauses that were never going to hold.
Should You Put These Clauses in Your BFA?
For most couples, a well-drafted sunset clause is worth considering, while fidelity and lifestyle clauses are better left out.
A sunset clause gives a genuine, enforceable way to match the agreement to changing circumstances, which is valuable given how long relationships often last before they end.
There were 47,216 divorces granted in Australia in 2024, and the median marriage lasted 13.2 years from wedding to divorce, so an agreement signed early may need to flex over more than a decade of change.
Fidelity and lifestyle clauses, by contrast, tend to add friction to the negotiation and create expectations the law will not back up.
If honesty, shared responsibilities, or similar values matter to a couple, those are worth talking through directly rather than trying to force them into a financial contract.
A lawyer can help separate what belongs in the agreement from what belongs in the relationship, so the final document does the job it is meant to do.
Need Help With Lifestyle, Fidelity, or Sunset Clauses in Your BFA?
The clauses that make a BFA strong are the ones drafted to match your circumstances and the requirements of the Family Law Act, and getting the wording right, especially for sunset clauses, is what keeps an agreement standing when it matters most.
As binding financial agreement lawyers, the team at my law firm can prepare a clear, fixed-fee BFA that protects what matters to you and leaves out the terms that would only cause trouble later.
Call us today on 1300-529-888 to talk through your situation.
Frequently Asked Questions
Can you put a fidelity clause in an Australian BFA?
You can write a fidelity clause into an Australian BFA, but there is no case law confirming a court would enforce one, so it carries real risk. Australia has had no-fault divorce since 1975, and a penalty for cheating sits outside the property and maintenance matters a BFA is built to decide, so its prospects of being upheld are poor.
Are lifestyle clauses in a BFA legally binding?
Lifestyle clauses covering behaviour, appearance, chores, or social media can be included in a BFA, but there is no case law confirming an Australian court would enforce them. They are widely seen as risky because they sit outside the property and maintenance matters a BFA is designed to settle, so they rarely add reliable protection.
What is a sunset clause in a binding financial agreement?
A sunset clause makes a BFA, or part of it, stop operating on a set date or on a certain event, such as a child’s birth. To be effective, it must be paired with a termination agreement under the Family Law Act. A clause that only asks the couple to review it is not enforceable on its own.
Can a BFA decide who keeps the family pet?
A BFA can record who keeps a family pet as part of dividing property, since the law has long treated animals as property. From 10 June 2025, courts deciding pet disputes must weigh specific factors and cannot order shared ownership. A clearly drafted BFA still lets a couple settle this themselves and avoid that court process.
Does a BFA have to be only about money?
A BFA does not have to deal only with money, but its enforceable core is financial. For married couples, the law allows property, financial resources, maintenance, and certain other matters. Non-financial terms like fidelity or lifestyle clauses can appear, yet their enforceability is untested and uncertain, because a court’s power under a BFA centres on property and finances.