Prenuptial Agreements in Canada: Marriage Contract Rules

Yes, you can sign a prenup in Canada, but there is no single Canadian prenup law. Each province sets its own rules for what the agreement must look like, what it can cover and when a court can set it aside. Ontario calls a prenup a marriage contract, and an agreement between unmarried partners a cohabitation agreement; Quebec requires a notarial marriage contract; BC and Alberta deal with spousal agreements inside their family property and support statutes.

This guide covers four jurisdictions: Ontario (Family Law Act, RSO 1990, c F.3, Part IV), British Columbia (Family Law Act, SBC 2011, c 25), Alberta (Family Property Act, RSA 2000, c F-4.7, and Family Law Act, SA 2003, c F-4.5) and Quebec (Civil Code of Québec), plus the federal Divorce Act on spousal support. It reflects the Ontario, BC, Quebec and federal consolidations current in October 2026 and the Alberta consolidations as published by Alberta King's Printer (Family Property Act current as of November 16, 2022; Family Law Act current as of June 11, 2025). Other provinces and territories are not covered.

What a prenup is called in each province

The name changes with the province, and so does the legal machinery behind it.

Ontario. Section 51 of the Family Law Act defines a "domestic contract" as "a marriage contract, separation agreement, cohabitation agreement, paternity agreement or family arbitration agreement." A prenup is a marriage contract under section 52. Section 52 also applies to people who are already married, so an agreement signed after the wedding (a postnup) is a marriage contract too.

British Columbia. The BC Family Law Act has no separate prenup or cohabitation-agreement category. Spouses "may make agreements respecting the division of property and debt" (s 92) and agreements on spousal support (s 163). "Spouse" in section 3 includes a married person and someone who has lived in a marriage-like relationship for at least two years (or, outside the property and pension parts, who has a child with the other person). Our BC common-law guide explains how that definition works for unmarried couples.

Alberta. Section 37 of the Family Property Act lets "spouses or adult interdependent partners" make a written agreement that "provides for the status, ownership and division of that property." If the agreement is enforceable under section 38, the Act's property-division rules in Part 1 do not apply to that property. Spousal and partner support agreements fall under section 62 of the Alberta Family Law Act.

Quebec. Spouses choose their matrimonial regime in a marriage contract. Under article 432 of the Civil Code, spouses who do not make one "are subject to the regime of partnership of acquests." Article 431 says "Any kind of stipulation may be made in a marriage contract, subject to the imperative provisions of law and public order," and those imperative provisions are where most of the limits come from.

How to make a valid prenup: the formal requirements

Getting the form wrong can make an otherwise careful agreement unenforceable. The four jurisdictions take quite different approaches.

Ontario: writing, signatures and a witness

Section 55(1) of Ontario's Family Law Act says a domestic contract, and an agreement to amend or rescind one, is "unenforceable unless made in writing, signed by the parties and witnessed." Sections 52 to 55 do not add a requirement for independent legal advice or financial disclosure; those come in later, as grounds a court can use to set the contract aside.

A minor can make a domestic contract, but only "subject to the approval of the court" (s 55(2)). Sections 55(3) and (4) deal with people who lack mental capacity, through a guardian or attorney with the court's prior approval, or the Public Guardian and Trustee.

British Columbia: written, signed and witnessed signatures

The BC Act defines a "written agreement" as one "in writing and signed by all parties" (s 1). For property agreements, the court's set-aside tests in section 93 apply to "a written agreement respecting division of property and debt, with the signature of each spouse witnessed by at least one other person"; the same person can witness both signatures (s 93(2)). A court may also apply section 93 to an unwitnessed written agreement "if the court is satisfied it would be appropriate to do so" (s 93(6)).

Alberta: a separate acknowledgment before your own lawyer

Alberta is the one jurisdiction here where a lawyer is built into the enforceability rule for property. Section 38(1) of the Family Property Act says the agreement "is enforceable if each party to the agreement has acknowledged, in writing, apart from the other party":

(a) that the party is aware of the nature and the effect of the agreement, (b) that the party is aware of the possible future claims to property the party may have under this Act and that the party intends to give up these claims to the extent necessary to give effect to the agreement, and (c) that the party is executing the agreement freely and voluntarily without any compulsion on the part of the other party.

Section 38(2) adds that the acknowledgment "shall be made before a lawyer other than the lawyer acting for the other party or before whom the acknowledgement is made by the other party." In practice, that means each of you sees a different lawyer.

Timing matters too. Under section 37(2), an agreement "entered into by 2 persons before marriage is unenforceable after the marriage unless it is clear in the agreement that the parties intended the agreement to apply or continue to apply after the marriage." A prenup that does not say it survives the wedding can fail on that ground alone.

Quebec: a notarial act

Article 440 of the Civil Code says "Marriage contracts shall be established by a notarial act en minute, on pain of absolute nullity." A signed private document is not enough. The notary also has notice of the contract entered in the register of personal and movable real rights (art 442).

The regime takes effect "on the day when the marriage is solemnized," and the parties cannot pick another date (art 433). Before the wedding, changes need all the parties to the contract and must themselves be made by marriage contract (art 437). During the marriage, the regime can be changed "provided the change itself is made by marriage contract" (art 438).

What a prenup can and cannot cover

Ontario, BC and Alberta all let couples agree on property and spousal support, and Quebec lets spouses set their matrimonial regime. In Ontario and BC, terms about your children's parenting and support do not bind a court in advance, and in Alberta a child support agreement does not stop either of you from applying for a child support order.

What you can include

Section 52(1) of Ontario's Act lets a marriage contract set out your "respective rights and obligations under the marriage or on separation, on the annulment or dissolution of the marriage or on death, including":

(a) ownership in or division of property; (b) support obligations; (c) the right to direct the education and moral training of their children, but not the right to decision-making responsibility or parenting time with respect to their children; and (d) any other matter in the settlement of their affairs.

Part I of the Act speaks to how property terms interact with equalization. Section 2(10) says "A domestic contract dealing with a matter that is also dealt with in this Act prevails unless this Act provides otherwise," and section 4(2), paragraph 6, lists among the property whose value "does not form part of the spouse's net family property": "Property that the spouses have agreed by a domestic contract is not to be included in the spouse's net family property." The matrimonial home rule in section 52(2) and the set-aside grounds in section 56(4) still apply; a family lawyer can tell you how they affect the terms you want. For pensions, section 56.1(2) says a domestic contract "may provide for the immediate transfer of a lump sum out of a pension plan, but, except as permitted under subsection (3), not for any other division of a party's interest in the plan."

In BC, section 92 lets spouses agree to:

(a) divide family property or family debt, or both, and do so equally or unequally; (b) include as family property or family debt items of property or debt that would not otherwise be included; (c) exclude as family property or family debt items of property or debt that would otherwise be included; (d) value family property or family debt differently than it would be valued under section 87

In Alberta, a section 37 agreement "may provide for the distribution of property between the spouses or adult interdependent partners at any time," including on separation or the dissolution of the marriage, and may cover property owned at or after the time the agreement is made (s 37(3)).

Our guide to dividing property on divorce explains the default rules a prenup would be changing in each province.

What you cannot lock in

Parenting arrangements and child support. In Ontario, a court "may disregard any provision of a domestic contract" on education, moral training, decision-making responsibility or parenting time where doing so is in the best interests of the child (s 56(1)), and may disregard a child support provision "where the provision is unreasonable having regard to the child support guidelines" (s 56(1.1)). BC goes further: an agreement on parenting arrangements (s 44(2)) or child support (s 148(1)) "is binding only if" it is made after separation, or when the parties are about to separate for the purpose of being effective on separation. A prenup signed before any separation is in sight cannot meet that test. In Alberta, a child support agreement "does not preclude a person from applying for a child support order" (FLA s 53(2)).

Ontario's matrimonial home. Section 52(2) says "A provision in a marriage contract purporting to limit a spouse's rights under Part II (Matrimonial Home) is unenforceable."

Ontario's chastity clauses. A provision taking effect on separation that makes a right "dependent upon remaining chaste" is unenforceable, although a term that ends on remarriage or cohabitation with someone else is not affected (s 56(2)).

Quebec's family patrimony. Article 414 says marriage "entails the establishment of a family patrimony," and article 415 lists what it includes: the family residences, household movables, "the motor vehicles used for family travel," "the benefits accrued during the marriage under a retirement plan" and Quebec Pension Plan registered earnings. Property received by succession or gift is excluded. On separation from bed and board, or when the marriage ends by divorce, death or nullity, its net value is divided equally (art 416). Article 423 then closes the door on contracting out:

The spouses may not, by way of their marriage contract or otherwise, renounce their rights in the family patrimony.

A spouse can renounce those rights only after the other spouse's death or after a judgment of divorce, separation from bed and board or nullity, by notarial act en minute or by a recorded judicial declaration (art 423), and a renunciation made by notarial act can be annulled for lesion or any other cause of nullity of contracts (art 424). Article 391 adds that spouses cannot derogate from the provisions of its chapter "whatever their matrimonial regime." So a Quebec marriage contract can set your matrimonial regime in place of the default partnership of acquests, but it cannot remove the family patrimony.

When a court can set a prenup aside

A signed agreement is a strong starting point, not a guarantee. Each province gives its courts specific grounds to undo all or part of it.

Ontario

Section 56(4) of the Family Law Act says a court may, on application, set aside a domestic contract or a provision in it:

(a) if a party failed to disclose to the other significant assets, or significant debts or other liabilities, existing when the domestic contract was made; (b) if a party did not understand the nature or consequences of the domestic contract; or (c) otherwise in accordance with the law of contract.

Those grounds apply "despite any agreement to the contrary" (s 56(7)), so a clause saying neither of you will ever challenge the contract does not switch them off.

British Columbia

For a witnessed property agreement, section 93(3) lets the court set aside or replace it only if one or more of these existed when you signed:

(a) a spouse failed to disclose significant property or debts, or other information relevant to the negotiation of the agreement; (b) a spouse took improper advantage of the other spouse's vulnerability, including the other spouse's ignorance, need or distress; (c) a spouse did not understand the nature or consequences of the agreement; (d) other circumstances that would, under the common law, cause all or part of a contract to be voidable.

Even if none of those applies, section 93(5) lets the court act if "the agreement is significantly unfair" considering "(a) the length of time that has passed since the agreement was made; (b) the intention of the spouses, in making the agreement, to achieve certainty; (c) the degree to which the spouses relied on the terms of the agreement." The court can also decline to act if it would not make an order substantially different from the agreement (s 93(4)). Unless all or part of the agreement is set aside, the court does not make a property order on the matters it covers (s 94(2)).

Alberta

Alberta's property rule works differently. The question is mainly whether the agreement met section 38 (the separate written acknowledgments before lawyers) and, for a prenup, section 37(2) (clear intent to continue after the marriage). Sections 37 and 38 do not list disclosure as an element. Section 37(4) also makes an agreement unenforceable by a spouse who, when it was made, "knew or had reason to believe that the marriage was void."

Quebec

A marriage contract not made by notarial act en minute is absolutely null (art 440), and every stipulation in it is subject to the imperative provisions of law and public order (art 431), including article 423. Other grounds for challenging a Quebec marriage contract are not addressed in this guide.

Agreements signed when a couple separates follow the same statutes but raise different practical issues; our guide to separation agreements in Canada covers those.

Spousal support waivers

Many prenups include a clause that one or both of you will not claim spousal support. Ontario, BC and Alberta allow that kind of term in principle, and each keeps a way for a court to look behind it; for married couples who divorce, the federal Divorce Act adds its own.

Ontario. Section 33(4) of the Family Law Act says the court "may set aside a provision for support or a waiver of the right to support in a domestic contract and may determine and order support," even if the contract excludes that section, in three situations:

(a) if the provision for support or the waiver of the right to support results in unconscionable circumstances; (b) if the provision for support is in favour of or the waiver is by or on behalf of a dependant who qualifies for an allowance for support out of public money; or (c) if there is default in the payment of support under the contract at the time the application is made.

British Columbia. Section 163(2) says a spouse "may agree to release the other spouse from liability for spousal support." Section 164(3) lets a court set aside or replace a support agreement on the same four grounds as the property rule, with disclosure framed as failing to disclose "income, significant property or debts." Under section 164(5), the court can also act where the agreement is significantly unfair, considering the time since it was made, changes in either spouse's "condition, means, needs or other circumstances," the intention to achieve certainty, reliance on its terms, and how well it meets the objectives in section 161.

Alberta. Section 62(1)(b) of the Family Law Act lets one spouse or adult interdependent partner agree "to release the other ... from liability for support." Under section 62(3), the court may not make a support order that differs from the agreement "unless the court is satisfied that the agreement is inequitable" and one of these exists: the person challenging it signed "without receiving independent legal advice"; for spouses, the removal of barriers to remarriage within a faith was a consideration; for adult interdependent partners, they later married each other; or one of them receives government financial assistance without reasonable support from the other.

The federal Divorce Act. Married couples who divorce can apply for spousal support under section 15.2 of the Divorce Act. Section 15.2(4) tells the court to consider "the condition, means, needs and other circumstances of each spouse," including "any order, agreement or arrangement relating to support of either spouse." A prenup is a factor, not a bar. The Divorce Act applies only to married spouses; unmarried partners rely on provincial law.

Justice Canada's Spousal Support Advisory Guidelines user's guide describes how courts approach a final agreement "waiving or time limiting spousal support or fixing a lump sum" on an initial application: "the two-part Miglin test applies to determine the weight to be given to the agreement." The same guide says the advisory guidelines "give no power to invalidate or override prior agreements," that providing less than the guidelines suggest "is not in and of itself a reason to set aside the agreement," and that "complete waivers" of spousal support "are often fairly easily overridden or set aside, especially where there are children." Our spousal support guide covers how support is calculated when there is no agreement.

Independent legal advice and financial disclosure

People often assume both are legal requirements for every prenup. The statutes split them more carefully than that.

Even where a statute does not require a lawyer, each of you getting separate advice and exchanging full financial information goes directly to the grounds courts use to set agreements aside. A family lawyer in your province can tell you what that looks like for your situation.

Comparing the four jurisdictions

Cohabitation agreements for unmarried couples

Ontario. Section 53(1) lets two people "who are cohabiting or intend to cohabit and who are not married to each other" make a cohabitation agreement on their rights and obligations "during cohabitation, or on ceasing to cohabit or on death," covering the same subjects as a marriage contract with the same limits on parenting. Under section 53(2), if the two of you later marry, the agreement "shall be deemed to be a marriage contract." Our Ontario common-law guide explains why a cohabitation agreement matters so much there, and the common-law relationships in Canada guide compares the provinces.

British Columbia and Alberta. BC's agreement rules apply to anyone who is a "spouse" under section 3, and Alberta's section 37 applies to adult interdependent partners as well as spouses. See our guides to common-law relationships in BC and adult interdependent partners in Alberta.

Quebec de facto spouses and the parental union. The Civil Code now contains a parental union regime (articles 521.20 and following). The Quebec government says a parental union forms when de facto spouses become the parents of the same child, and that "This applies only to births or adoptions that occur on or after June 30, 2025." Spouses in a parental union "may not derogate" from its rules except as the law allows (art 521.21). They can withdraw from the parental union patrimony rules by mutual agreement, but only "by notarial act en minute, on pain of absolute nullity," and if the withdrawal is made within 90 days of the start of the union, the patrimony "is deemed never to have been established" (art 521.33). Our guide to common-law couples in Quebec explains the regime in detail, including what it does not give you.

Other provinces and territories

Manitoba, Saskatchewan, Nova Scotia, New Brunswick, Prince Edward Island, Newfoundland and Labrador, Yukon, the Northwest Territories and Nunavut each have their own family property and support laws, and this guide does not cover them. If you live in one of them, check that province's or territory's family law statute for the formal requirements and set-aside grounds, or speak with a family lawyer there before you sign. The Canada family law hub links our province-by-province guides.

Before you sign

The circumstances at signing matter. BC's Act names taking improper advantage of a spouse's ignorance, need or distress as a ground to set an agreement aside, and Ontario's includes ordinary contract-law grounds, so leaving real time to negotiate, take advice and exchange financial information before the wedding goes to the grounds courts use to set agreements aside. If you are also arranging the ceremony in Ontario, our Ontario marriage licence guide covers the licence itself. If a marriage is ending rather than starting, the Ontario divorce guide explains the divorce process, and any marriage contract you signed will be part of that picture.

Frequently Asked Questions

Are prenups legal and enforceable in Canada?

Yes, but under provincial law, not one national law. Ontario calls them marriage contracts under its Family Law Act, Quebec requires a notarial marriage contract under the Civil Code, and BC and Alberta deal with spousal agreements in their own family statutes. Whether a particular agreement holds up depends on that province's formal rules and on the grounds its courts can use to set an agreement aside.

What is the difference between a prenup and a marriage contract in Ontario?

In practice they are the same thing. Ontario's Family Law Act does not use the word prenup; section 52 calls it a marriage contract and lets people who are married or intend to marry make one. The same section covers an agreement signed after the wedding, sometimes called a postnup.

Do we each need a lawyer to sign a prenup?

It depends on the province. Ontario's Act requires writing, signatures and a witness, not lawyers, but a party who did not understand the contract has a ground to set it aside. In Alberta, an agreement on property is enforceable only if each of you acknowledges it in writing before a lawyer who does not act for the other, and signing a support agreement without independent legal advice is a ground for challenging it. In Quebec, a marriage contract must be made by a notary.

Can a prenup decide custody or child support?

Not in a way that binds a court. In Ontario a court can disregard parenting terms that are not in the child's best interests, and child support terms that are unreasonable having regard to the child support guidelines. In BC, agreements on parenting and child support are binding only if made at or after separation. In Alberta, a child support agreement does not stop anyone from applying for a child support order.

Can a prenup waive spousal support in Canada?

A waiver is allowed, but it can be overridden. Ontario courts can set aside a waiver that results in unconscionable circumstances, BC courts can set aside an agreement that is significantly unfair, and Alberta courts can depart from an inequitable agreement in listed circumstances. Under the federal Divorce Act, an agreement is one factor the court considers, and Justice Canada notes that complete waivers are often fairly easily overridden, especially where there are children.

Can a marriage contract protect the matrimonial home in Ontario?

Not by limiting the other spouse's rights to it. Section 52(2) of Ontario's Family Law Act says a provision in a marriage contract purporting to limit a spouse's rights under Part II (Matrimonial Home) is unenforceable. Ask a family lawyer how that interacts with any property terms you want to include.

Can Quebec couples opt out of the family patrimony with a prenup?

No. Article 423 of the Civil Code says spouses may not renounce their rights in the family patrimony by marriage contract or otherwise. A spouse can renounce them only after a death, or after a judgment of divorce, separation from bed and board or nullity, by notarial act or by a recorded judicial declaration.

Should common-law couples sign a cohabitation agreement?

Many do, because unmarried partners do not always get the same property rules as married spouses. In Ontario, a cohabitation agreement is a domestic contract under section 53 of the Family Law Act, and if the two of you later marry it is deemed to be a marriage contract. In Quebec, couples who become parents of a child born or adopted on or after June 30, 2025 can fall under the parental union regime automatically.

Does a prenup signed in Alberta still work after we get married?

Only if the agreement makes that clear. Section 37(2) of Alberta's Family Property Act says an agreement made by two people before marriage is unenforceable after the marriage unless it is clear in the agreement that the parties intended it to apply or continue to apply after the marriage.

Can we change or cancel our marriage contract later?

Yes, but the change has to meet the same formal rules. In Ontario, an agreement to amend or rescind a domestic contract is unenforceable unless it is in writing, signed by both of you and witnessed. In Quebec, a change to the matrimonial regime during the marriage must itself be made by marriage contract, which means a notarial act.