What is a marriage contract?
A marriage contract, often called a prenup, is a written agreement that sets your own rules for property, support and other matters if the marriage ends. It can be signed before or during the marriage. It usually holds up if it is in writing, signed and witnessed, both spouses disclosed their finances, and each understood it, ideally with their own lawyer.
Key points
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A marriage contract can decide how property is divided, protect a business or a family gift, and set or waive spousal support.
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It cannot decide parenting arrangements in advance, and it cannot limit a spouse's rights to the matrimonial home.
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It must be in writing, signed by both spouses and witnessed, or it is unenforceable.
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A court can set it aside if a spouse hid significant assets or debts, did not understand it, or was pressured. The bar is high.
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Full financial disclosure, time before the wedding, and independent legal advice for each spouse help it last.
Planning to marry? Book a free 15-minute call about a marriage contract.
What can a marriage contract cover?
Under the Family Law Act, people who are married, or intend to marry, can make a marriage contract. It can set their rights during the marriage, on separation, on annulment or divorce, and on death. Some subjects are off limits or stay under the court's control.
It can cover:
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how property is owned and divided, including excluding assets from net family property;
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a business, professional practice, family company or trust interest;
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gifts and inheritances, and the income and growth from them;
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spousal support: an amount, a time limit, or a waiver;
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debts, and who is responsible for them;
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rights on death, alongside your wills; and
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the children's education and moral training, subject to their best interests.
It cannot cover, or a court can override:
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Parenting. Decision-making responsibility and parenting time are decided when the time comes, in the children's best interests.
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The matrimonial home. A term that limits a spouse's rights to the home, such as living there or consenting before it is sold or mortgaged, is unenforceable.
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Child support. A court can disregard child support terms that are unreasonable compared with the Child Support Guidelines. It can also disregard terms on the children's education or upbringing that are not in their best interests.
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Chastity clauses. A term that makes a spouse's rights after separation depend on remaining "chaste" is unenforceable.
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Unfair support terms. A court can set aside a support term or waiver that leaves a spouse in unconscionable circumstances or on public assistance, or where support payments are in default.
A cohabitation agreement automatically becomes a marriage contract if the couple later marry each other. See Cohabitation agreements in Ontario.
Why is the matrimonial home often the reason for a marriage contract?
Ontario treats the matrimonial home differently from other property. If you own a home when you marry, you normally get credit for its value on the wedding day when property is divided. But if it is the family home when you separate, that credit is lost, and its full value goes into your net family property. See Property division in Ontario and The matrimonial home in Ontario.
The same is true of a home bought with a gift or inheritance. Inherited property is usually excluded, but not if it becomes the matrimonial home.
A marriage contract can change this. It can say the home, or the value you brought in, stays yours. What it cannot do is limit your spouse's right to live in the home, or let you sell or mortgage it without their consent.
Other common clauses:
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Business protection: excluding a business or professional corporation, and its growth, from equalization, often with a promise not to claim against it.
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Gifts and inheritances: keeping their growth and income separate, and agreeing they will not go into the home or joint accounts.
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Spousal support: a waiver, a cap, or a formula tied to the length of the marriage. Courts look closely at these, especially after a long marriage or once children are born; see below.
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Debts: each spouse is responsible for debts in their own name.
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Death: whether a surviving spouse can choose an equalization payment instead of what the will gives them.
Will a marriage contract hold up in court?
A well-made one usually does. Courts start from respect for agreements that adults made with advice. The person trying to undo one has to prove why it should go.
The formal requirements. A domestic contract is unenforceable unless it is in writing, signed by both spouses, and witnessed. A handwritten note or an exchange of emails is not enough.
When a court can set it aside. A court may set aside a marriage contract, or part of it, in three situations:
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a spouse failed to disclose significant assets, debts or other liabilities that existed when the contract was made;
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a spouse did not understand the nature or consequences of the contract; or
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it is invalid under the ordinary law of contract, for example because of duress, undue influence, misrepresentation or unconscionability.
The Court of Appeal applies this in two steps. First, the spouse challenging the contract must prove one of these grounds. Second, the judge decides whether it is fair, in all the circumstances, to set the contract aside (Butty v. Butty, 2009 ONCA 852). Proving a ground does not guarantee the contract will be set aside.
What failure looks like. In LeVan v. LeVan, 2008 ONCA 388, the husband's family required a marriage contract protecting a business worth tens of millions. His disclosure was misleading, and the wife's legal advice was rushed and based on that disclosure. She signed two days before the wedding after being told there would be no marriage otherwise. The contract was set aside, and she received a large equalization payment.
What success looks like. In Gorman v. Sadja, 2020 ONSC 6192, the husband argued that disclosure was incomplete and that the contract was presented ten days before the wedding. The court disagreed. He had a lawyer, knew the wife's assets and chose not to ask for more, and the timing alone was not duress.
Spousal support waivers. A waiver can still be reviewed. Under the Family Law Act, a court can set it aside if it results in unconscionable circumstances, leaves a spouse on public assistance, or support is in default. In a divorce, courts ask whether the agreement was fair when made and whether it still reflects what the spouses expected (Miglin v. Miglin, 2003 SCC 24). Contracts signed before children were born are especially open to review on support.
How do you make a marriage contract that lasts?
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Start early. Begin at least three to four months before the wedding, and sign well before the invitations go out. A contract signed days before the ceremony invites an argument about pressure, even though timing alone does not decide it.
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Disclose everything significant. Exchange a written summary of assets, debts and income, with values and supporting documents, and attach it to the contract. Leaving out a significant asset is one of the main reasons contracts are set aside.
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Each spouse gets their own lawyer. One lawyer cannot act for both. Independent legal advice for the spouse giving up rights is the main protection against a later claim that they did not understand the contract. See Independent legal advice in Ontario family law.
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Explain the trade-off in plain words. The contract should show what each spouse would receive under the Family Law Act and what they will receive instead. Courts are more likely to uphold an agreement whose consequences were spelled out.
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Keep it fair enough to survive change. Consider reviews or step-ups for spousal support after a set number of years or when children arrive, rather than a flat waiver.
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Follow it. If you mix excluded money into the home or a joint account, the contract may not protect it. Keep separate property separate, and update the contract if your plans change.
You can also sign a marriage contract after the wedding, sometimes called a postnup. The same rules apply. If you have already separated, the agreement you need is a separation agreement. See Separation agreements in Ontario.
Talk to a family lawyer about a marriage contract
Start with a free 15-minute call to talk through your plans and the next step. From there, we can draft your marriage contract, or advise you on one your partner's lawyer prepared.
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A free 15-minute phone call to talk through your situation and the next step
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Marriage/Prenuptial Agreement from $1,299 plus HST, including a consultation, drafting and two rounds of revisions
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Independent Legal Advice on a contract your partner's lawyer prepared: $699 plus HST
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Other work at $275 an hour or under a limited-scope retainer
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Later meetings by phone, by video or in person at 5200 Yonge Street, Suite 200, North York
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Urgent or out-of-hours: leave a voicemail or send a text to 416-858-1320
Book a free 15-minute call about your separation agreement · Call 416-858-1320
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Last reviewed: October 12, 2026
This page is general information about Ontario and federal law, not legal advice. Reading it or contacting us does not create a lawyer-client relationship. Laws and court fees change; check the date above.