Marriage Contracts (Prenuptial Agreements) in Ontario

What Is a Marriage Contract?

A marriage contract is a written agreement between two people who are married to each other, or who intend to marry, setting out their respective rights and obligations during the marriage, on separation, on annulment or dissolution of the marriage, or on death. Under Ontario's Family Law Act, a marriage contract is one type of "domestic contract" — a category that also includes separation agreements and cohabitation agreements, all governed by related rules about how they must be made and when a court can interfere with them.

In everyday language, a marriage contract signed before the wedding is usually called a "prenuptial agreement" or "prenup," and one signed after the wedding is often called a "postnuptial agreement" or "postnup." These are not separate legal categories under Ontario law — both are simply a "marriage contract," and the same statutory rules apply regardless of when it was signed.

Before vs. During Marriage

Two people who are not yet married but intend to marry can enter into a marriage contract in anticipation of the wedding. It generally takes effect once the marriage actually takes place — if the wedding never happens, a prenuptial marriage contract generally does not take effect as intended.

Spouses who are already married can also enter into a marriage contract at any point during the marriage — for example, after receiving an inheritance, starting a business, or simply deciding to formalize an understanding the couple already had. There is no rule against signing one years into a marriage, and doing so does not require any special circumstance or court involvement.

A cohabitation agreement between partners who later marry each other is a related but distinct starting point — see Marriage Contracts vs. Cohabitation Agreements below.

What a Marriage Contract Can Address

A marriage contract can generally address most of the financial consequences of marriage, separation, or death, including:

• Ownership, use, and division of property, including how the matrimonial home is owned or valued
• Whether property will be excluded from, or included in, an equalization of net family property claim
• Spousal support obligations, including amount, duration, and circumstances for review
• The right to direct the education and moral training of any children of the marriage
• Any other matter in the settlement of the spouses' affairs

Couples use marriage contracts for a wide range of reasons: protecting property owned before the marriage, addressing a family business or inheritance, clarifying how debts will be handled, or simply creating certainty about what would happen financially if the marriage were to end. There is no requirement that a couple be wealthy or have complicated finances to use one.

What a Marriage Contract Cannot Do

A marriage contract is a powerful planning tool, but Ontario law places real limits on what it can achieve. Two limits matter enough that every couple considering one should understand them before signing.

It Cannot Bind a Court on Parenting Matters

A marriage contract cannot determine decision-making responsibility or parenting time for children of the marriage in a way that binds a court. Provisions touching on a child's welfare remain subject to a court's ongoing oversight based on the best interests of the child at the relevant time, not simply what the spouses agreed to years earlier. Most families never need a court to revisit these terms, but the possibility remains open in a way it generally is not for property or support terms.

It Generally Cannot Limit a Spouse's Right to Live in the Matrimonial Home

This is one of the most important — and most commonly misunderstood — limits on a marriage contract. Under the Family Law Act, a provision in a marriage contract that purports to limit either spouse's right to possession of the matrimonial home is generally unenforceable. In practical terms, this means that as long as both spouses are alive and a property remains the matrimonial home, a marriage contract cannot take away either spouse's right to live there, no matter what the contract itself says or who owns the home on paper.

This limit is specific to possession rights, not to the home's value. A marriage contract can still generally determine who owns the matrimonial home, and it can still exclude the home's value from an equalization claim the way other property can be excluded. What it cannot do is convert one spouse's right to occupy the home into something the other spouse can sign away in advance. If the matrimonial home is important to your planning, read how the matrimonial home is treated in Ontario before finalizing terms.

Formality Requirements

A marriage contract must meet the same general formal requirements that apply to other domestic contracts under the Family Law Act: it must be made in writing, signed by both parties, and witnessed. A verbal understanding between spouses, however genuine, does not meet this standard and is generally unenforceable as a marriage contract.

These requirements, along with how signing and witnessing typically work in practice, are explained in more detail on our separation agreements page, since the same formalities apply across domestic contracts generally. The unique planning questions for a marriage contract are less about how it is signed and more about timing and content — addressed throughout this page.

Why Independent Legal Advice Matters Here

Ontario law does not strictly require independent legal advice (ILA) for a marriage contract to be valid — spouses can, in principle, sign one without either person consulting a lawyer. In practice, ILA is very commonly recommended for marriage contracts specifically, for a few reasons that are somewhat particular to this type of agreement.

Marriage contracts are frequently signed close to a wedding date, a timing pressure that does not usually apply to a separation agreement negotiated after a relationship has already ended. A contract signed quickly, under time pressure, or without one spouse fully understanding what they are giving up, is generally more vulnerable to a later challenge. Independent legal advice — meaning each spouse gets advice from their own separate lawyer, since a single lawyer generally cannot advise both — helps create a record that each spouse understood the terms and entered into the agreement voluntarily, which can matter a great deal if the marriage contract is ever tested years later.

Can a Marriage Contract Be Challenged Later?

A properly executed marriage contract is generally binding, but like other domestic contracts under the Family Law Act, it is not automatically beyond challenge. A court can set aside part or all of a marriage contract in certain circumstances — for example, where a spouse failed to disclose significant assets, debts, or other liabilities that existed when the agreement was made, or where a spouse did not understand the nature or consequences of what they were signing.

Because marriage contracts are often signed under real or perceived time pressure before a wedding, courts and lawyers alike pay particular attention to how the agreement came together: how much time each spouse had to review it, whether both received independent legal advice, and whether financial disclosure was full and honest. See Challenging a Separation Agreement for a fuller discussion of the general grounds that can apply to domestic contracts, including marriage contracts.

Marriage Contracts vs. Cohabitation Agreements

A cohabitation agreement is a similar type of domestic contract for two people who are living together, or intend to live together, but are not married. Many of the same planning goals — protecting property brought into the relationship, addressing support, clarifying expectations — apply to both.

The two are connected in an important way: under the Family Law Act, a cohabitation agreement is generally deemed to become a marriage contract automatically if the parties later marry each other, unless the cohabitation agreement itself says otherwise. Couples who already have a cohabitation agreement and are planning to marry should have it reviewed beforehand to confirm it still says what they intend once it takes on the different legal character of a marriage contract.

Frequently Asked Questions