Prenuptial Agreements in Ontario (2026): What You Need to Know

A prenuptial agreement — called a marriage contract in Ontario — is a legally binding agreement signed before marriage that sets out how assets and support will be handled if the marriage breaks down.

Done properly, a marriage contract is one of the most effective tools for protecting your financial interests. Done improperly, it may not be worth the paper it’s written on.

What Can a Marriage Contract Cover?

A marriage contract in Ontario can address:

• Property division: How assets owned before marriage will be treated, how assets acquired during the marriage will be divided
• Exclusion of the matrimonial home: Attempting to remove the matrimonial home from the equalization calculation (subject to important limitations — see below)
• Spousal support: Whether support will be paid, and how much
• Ownership and division of specific assets (business interests, inheritance, investments)

What Cannot Be Addressed?

A marriage contract cannot limit or waive:

• Child support — you cannot contract out of your obligation to pay child support under the guidelines
• Decision-making authority regarding children — custody and access issues cannot be predetermined in a contract
• Rights to possession of the matrimonial home during the marriage (though division of its value can be addressed)

What Makes a Marriage Contract Enforceable?

Ontario courts will examine several factors when asked to uphold or set aside a marriage contract:

1. Independent Legal Advice (ILA)

Each party must receive independent legal advice from their own lawyer before signing. This is the single most important requirement. Without it, the agreement is at serious risk of being set aside.

2. Full Financial Disclosure

Both parties must fully disclose their financial situation — assets, liabilities, income — before signing. Concealing assets or misrepresenting financial circumstances is a ground for setting aside the agreement.

3. Voluntary Signing

The agreement must be signed freely, without duress, coercion, or undue pressure. Agreements signed in the days before a wedding under significant time pressure are at higher risk of challenge.

4. A Witness

The agreement must be signed in the presence of a witness.

5. Fair and Reasonable Terms

While courts generally respect the parties’ autonomy, grossly unfair terms — particularly those that leave one spouse with nothing — may be set aside, especially if circumstances have changed significantly since signing.

The Matrimonial Home: A Special Challenge

One of the most common goals of a marriage contract is to protect a home owned before marriage. Under Ontario law, the full value of the matrimonial home at the date of separation is included in the equalization calculation — even if one spouse owned it before the marriage.

A marriage contract can attempt to address this, but the courts have sometimes found matrimonial home provisions unenforceable. Careful drafting by an experienced family law lawyer is essential.

Timing: When Should You Sign?

The earlier, the better. A contract signed months before the wedding, with adequate time for each party to obtain legal advice and review the terms, is far more likely to be upheld than one signed the week before the ceremony.

Practical Advice

A marriage contract is an investment in clarity and protection. If you are entering a marriage with significant assets, a business, an inheritance, or children from a previous relationship, the cost of a properly drafted marriage contract is modest compared to the potential consequences of not having one.

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This article was written by Miao He (何淼), Ontario lawyer (LSO #83315K) and China-licensed lawyer, focusing on family law for the Chinese-Canadian community in the GTA.