What Goes in a Prenup? Clauses, Provisions, and What to Leave Out

A prenup in Canada — called a marriage contract in Ontario — covers property division, spousal support, debt allocation, pension treatment, inheritance protection, and estate coordination. The document typically runs 10–30 pages and is organized by asset class. What's in it, and how it's drafted, determines whether it holds up when it matters.

Property — what stays separate, what gets shared

The largest and most important section of any marriage contract. Under s. 52(1) of the Family Law Act R.S.O. 1990, c. F.3, a marriage contract can address ownership and division of property acquired at any point — before or during the marriage. Property clauses define three things.

Separate property: What stays with the person who owns it — pre-marriage assets, gifts, inheritances, specific accounts or business interests. Named specifically wherever possible. "Spouse A's RRSP at [institution], account number [X], with a balance of $[Y] as of the date of this agreement" is more defensible than "Spouse A's registered savings."

Shared (marital) property: What will be divided at separation — typically assets acquired together during the marriage, joint home equity, savings built from joint income. The contract can set a specific division formula rather than deferring entirely to the default equalization calculation.

Growth and appreciation: Whether the increase in value of separate property during the marriage is shared or stays with the original owner. This is where the matrimonial home rule creates Ontario's most significant surprise — under FLA s. 4(1), a home that becomes the matrimonial home cannot have pre-marital equity deducted. A property clause specifically addressing this is the most common and most financially consequential clause in Ontario marriage contracts.

Property clauses have the highest survival rate in Ontario courts. Dougherty v. Dougherty (2016 ONCA 781) confirmed that a court cannot set aside a contract merely because the outcome is unequal — there must be a procedural defect. Well-documented property exclusions with attached financial disclosure schedules are the most defensible provisions in any prenup.

For the full picture on what a marriage contract covers under Ontario's Family Law Act, including what property clauses can and can't do for the matrimonial home, that article covers the legal framework in detail.

Spousal support — the most contested section

Support clauses define whether either spouse can claim support at separation, in what amount, for how long, and under what conditions. The range of options:

A bare waiver. "Neither party shall have any obligation to pay spousal support." This is the most vulnerable clause type. Under FLA s. 33(4), courts can override a support waiver if enforcing it would leave a spouse in financial hardship serious enough to require social assistance. Bare waivers where one spouse later sacrificed career for family are regularly challenged and modified.

An SSAG-anchored formula. Support is defined within the Spousal Support Advisory Guidelines range, with specified caps, duration limits, and review triggers. Courts are substantially more comfortable upholding structured support provisions than bare waivers — they demonstrate the parties were not trying to produce an unconscionable outcome, just a defined one.

A minimum guarantee. A floor that exceeds what default law would provide — used when one spouse anticipates reducing their career for family. A marriage contract can guarantee more than the law would otherwise give, not just less.

Career interruption compensation. Lump-sum payments, mandatory RRSP contributions, or enhanced property shares triggered by a career pause for caregiving. Expressly permissible under FLA s. 52(1)(b) and (d). This is one of the most practically important provisions for couples where one partner plans to reduce paid work for children — it addresses the financial asymmetry that spousal support alone rarely compensates fully.

Support provisions are the most frequently challenged section of any prenup in Canada. Structured, SSAG-referenced clauses with review triggers are substantially more durable than absolute waivers.

Debt — keeping your financial problems separate

Debt clauses confirm that pre-marital and business liabilities stay with the person who brought them in, and define how debt incurred during the marriage is handled.

Standard language: "Each party's pre-existing debts as listed in Schedule [X] remain solely that party's responsibility. No claim shall lie against the other party for those debts." The financial disclosure schedule — listing all current debts at the time of signing — is what makes this clause documentable and defensible.

For couples where one partner owns a business or carries professional liability exposure, debt clauses define that business creditors cannot reach the other spouse's personal assets through the marriage structure. The important caveat: the contract binds the spouses, not third-party creditors. What it does is maintain genuine structural separation between one spouse's liabilities and the other's assets — making the pathway to those assets harder, not contractually blocked.

Student loan allocation is increasingly common in Canadian prenups — roughly 40% of millennials cite debt protection as their primary motivation for a prenup, often specifically to protect their partner from their own student debt rather than the other way around.

Pensions and retirement assets

Pension clauses define how pension value is treated at separation — what portion is excluded, how it's valued, and how it's offset against other assets. In Ontario, pension value accumulated during marriage is included in net family property equalization by default, covering both defined-benefit and defined-contribution plans.

A pension clause typically addresses three things:

Pre-marriage accrual exclusion. "The value of Spouse A's DB pension accrued before the date of marriage is excluded from net family property. Only pension growth during the marriage is subject to equalization." For a public-sector worker with eight or ten years of service before marriage, this exclusion can protect $80,000–$200,000 in accrued pension value.

Valuation methodology. Pre-agreeing on the termination or retirement method — which can produce significantly different numbers for the same pension — eliminates a common and expensive dispute at separation.

Offsetting mechanism. The pension is offset against home equity or investment portfolio rather than divided directly, preventing a situation where one spouse is forced to commute a DB pension to satisfy equalization.

One limitation that cannot be contracted around: CPP credit splitting on divorce under Canada Pension Plan s. 55.1. Ontario has not enacted opt-out legislation. A pension clause addresses employer pensions, RRSPs, and TFSAs — not CPP credits accumulated during the marriage.

Inheritance and estate provisions

Inheritance clauses protect assets received during the marriage from the commingling that causes them to lose their exclusion — the process by which inherited funds become shareable when mixed into joint accounts or used toward the matrimonial home.

In Ontario, inheritances are already excluded from net family property by default. But that exclusion is fragile. A marriage contract makes it explicit and adds anti-commingling provisions: "Any inheritance received by Spouse A during the marriage shall remain Spouse A's separate property, regardless of how those funds are held or used." This removes the burden of tracing — the inheriting spouse no longer needs to prove funds stayed separate.

Estate provisions address what happens when a spouse dies. Under FLA s. 5(2), a surviving spouse in Ontario has the right to claim equalization of net family property on the death of their partner, the same calculation that applies at separation. A death provision can waive or limit this claim — particularly important for blended families where children from prior relationships are the intended beneficiaries of the estate. These provisions need to coordinate with the will: if the marriage contract waives equalization on death, the will needs to point in the same direction.

What courts won't enforce

Three categories of provisions that are void or unenforceable in every Canadian province:

Child custody and child support. Courts are legally required to determine both at the time of separation based on the child's best interests. No prior agreement can bind this outcome. Including these clauses doesn't void the rest of the contract — a severability clause handles that — but they have no legal effect and their presence signals to courts that the agreement was drafted without adequate care about scope.

Restrictions on possession of the matrimonial home during marriage. Under FLA s. 26(1), both spouses have equal possessory rights during the marriage regardless of title or what the contract says. A prenup can define how equity is treated at separation — it cannot remove the right to live there while married.

Quebec's family patrimony. Under the Civil Code of Québec, the family patrimony — family residences, furnishings, motor vehicles, and certain pension benefits accumulated during the marriage — cannot be waived or modified by marriage contract. Quebec operates a mandatory regime that is fundamentally different from common-law provinces; planning in Quebec requires a notarial contract and works within the patrimony rather than around it.

Lifestyle and infidelity clauses — weight, appearance, household chores, sexual frequency, penalties for infidelity — are generally unenforceable in Canada and can undermine the agreement's credibility with a court even for the clauses that would otherwise hold up. Courts treat them as non-financial and contrary to public policy. A clause that might seem harmless in isolation can invite scrutiny of the entire document.

The enforceability spectrum — from strong to weak

Not all permissible clauses are equally defensible in practice:

Strongest: Specific property exclusions with named assets, current values, and attached signed disclosure schedules. Rare for courts to interfere with clear, well-documented property division.

Strong: SSAG-anchored spousal support with defined ranges, duration caps, and review triggers. Demonstrates the parties weren't producing an unconscionable outcome — just a predictable one.

Moderate: Business protection clauses with pre-agreed valuation methodology, especially when attached to a CBV valuation at signing. More defensible with specifics; weaker with general exclusion language.

Weaker: Career interruption and lifestyle provisions. Permissible under Ontario law but less tested at the appellate level. More enforceable when financially specific rather than aspirational.

Weakest: Bare support waivers and infidelity penalties. Support waivers are the most frequently challenged provisions in Canadian prenup litigation. Infidelity clauses are specifically flagged in Ontario as problematic — the conduct of spouses is not to be considered in support determinations under the Divorce Act.

For everything courts look for when a marriage contract is challenged, see what makes a prenup enforceable in Canada — including the ranked grounds for setting agreements aside.

How it differs by province

The core content is consistent across Canada but three specific rules vary meaningfully:

Alberta has the strictest formalities in common-law Canada. Under the Matrimonial Property Act, both parties must receive independent legal advice from their own separate lawyers, and each lawyer must sign a Certificate of Acknowledgment. Without those certificates, property-division provisions can be set aside regardless of how fair the terms are.

BC assesses fairness at the time of enforcement, not formation. An agreement that was reasonable at signing can be reopened if changed circumstances make it "significantly unfair" at the time it's applied — a materially broader standard than Ontario's approach.

Ontario and most common-law provinces assess fairness at formation. If the agreement was procedurally sound and reasonably fair when signed, courts are generally reluctant to override it. The onus falls on the party seeking to set aside the agreement, not the party trying to enforce it.

Quebec is an entirely different framework — marriage contracts executed before a notary, matrimonial regimes chosen from defined options, and a mandatory family patrimony that cannot be waived.

Frequently Asked Questions

What is the most important clause in a prenup?

Financial disclosure is the foundation, not a clause — without it, no clause is safe. Among the substantive provisions, property clauses are the most defensible and the most important for couples with significant pre-marriage assets. Support clauses are often the most financially consequential for couples with income gaps or planned caregiving arrangements — and the most frequently challenged.

Can a prenup include anything about children?

Not meaningfully. Child custody, parenting time, and child support cannot be predetermined in a prenup anywhere in Canada. Courts determine these at separation based on the child's best interests. Financial expectations for children's education (RESP contributions, private school, extracurriculars) are sometimes included but are generally unenforceable as binding obligations.

What's the difference between a sunset clause and a review clause?

A sunset clause terminates the entire prenup after a specified period or event — after 15 years of marriage, or on the birth of a child. A review clause requires the parties to revisit the agreement at intervals without automatically terminating it. Review clauses are generally more protective for both parties than sunset clauses, which can leave a marriage without any agreement at all at exactly the moment circumstances have changed most significantly.

Can a prenup cover a business started after marriage?

Yes — under Ontario's FLA s. 52(1), a marriage contract can address property regardless of when it's acquired. A clause can state that any business started by a named spouse during the marriage, and any increase in its value, is excluded from equalization. The clause needs to be specific about the asset type and pre-agree on a valuation methodology. See can a prenup protect future assets in Canada for the full breakdown by asset class.

What makes a prenup clause unenforceable?

The most common grounds: the clause involves something courts are legally required to decide (child custody, child support); it's so one-sided it shocks the conscience; it relies on provisions specifically voided by statute (restricting possession of the matrimonial home in Ontario, waiving Quebec's family patrimony); or it was drafted without full financial disclosure or ILA for both parties. Lifestyle clauses about personal behaviour are generally unenforceable in practice even when not specifically prohibited.

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This article provides general information about Canadian family law and does not constitute legal advice. Laws vary by province. For advice specific to your situation, consult a licensed family lawyer in your province.