Prenuptial Agreement in
Ontario

In Ontario, the agreement is formally called a "marriage contract" and is classified as a type of domestic contract under the Family Law Act. The terms "prenuptial agreement" and "prenup" are widely understood but are not the legislative terminology. An Ontario marriage contract must be in writing, signed by both parties, and witnessed — witnessing is a mandatory statutory requirement, not merely a recommendation.

An Ontario marriage contract cannot limit or override a spouse's right to possession of the matrimonial home. This is a statutory protection set out in the Family Law Act that parties cannot contract out of. Additionally, marriage contracts cannot contain provisions that purport to direct the custody or access arrangements for children born of the marriage, as those matters are always decided based on the best interests of the child.

Under the Ontario Family Law Act, the default rule is that each spouse calculates their net family property — the growth in their net worth during the marriage — and the higher-value spouse pays half the difference to the other. A marriage contract can modify this by specifying which assets are excluded from each spouse's net family property calculation, allowing assets brought into the marriage or received as gifts to remain separate from equalization.

Yes — witnessing is a mandatory requirement under the Ontario Family Law Act, not merely a best practice. Each party's signature must be witnessed by at least one person. Unlike some other provinces, this is a statutory condition of validity. Notarization is not required by statute but is commonly done as an additional protective measure.

An Ontario marriage contract can include spousal support provisions, but courts in Ontario retain broad discretion under both the Family Law Act and the federal Divorce Act to award support regardless of what the contract states. Ontario courts are particularly willing to override spousal support waivers when a significant amount of time has passed and circumstances have changed considerably since the contract was signed.

Yes. Marriage contracts are expressly authorized by s. 52 of Ontario's Family Law Act and are binding when they meet s. 55(1): in writing, signed by both partners, and witnessed. You can prepare the agreement yourselves — no lawyer is required to draft it. Courts enforce properly made contracts, setting them aside under s. 56(4) only for non-disclosure of significant assets or debts, failure to understand the contract, or ordinary contract-law grounds like duress.

Partly. A marriage contract can address who owns the home and how its value is treated if you separate, but s. 52(2) of the Family Law Act says it cannot limit either spouse's right to possession of the matrimonial home — both spouses keep an equal right to live there regardless of title. The home also gets special treatment in equalization: its full value is typically shared even if one spouse owned it before marriage, so addressing it clearly in your contract matters.

In Ontario, lawyer-drafted marriage contracts typically cost $2,000 to $5,000 CAD, and Toronto family law firms commonly quote $3,000 to $8,000+ where negotiations run long or finances involve businesses or real estate — with each spouse's independent legal advice billed on top. Creating your agreement online with prenups.ai costs a flat $349, and you can add optional independent legal advice afterward, usually $500 to $1,000 per person in Ontario.

With prenups.ai, you can have a draft prenuptial agreement in under 20 minutes. Traditional attorney routes in Ontario typically take 2–6 weeks due to scheduling, drafting, negotiation, and review. No specific statutory timing requirement. The agreement should be signed well before the wedding to demonstrate voluntariness. We recommend starting the process at least 2–3 months before your wedding to allow time for review and any revisions.

Yes. Ontario does not require you to have an attorney to create a valid prenuptial agreement. However, having each party consult with independent legal counsel significantly strengthens enforceability. Many couples use prenups.ai to create the initial draft and then have it reviewed by attorneys, which is much more affordable than starting from scratch.

Without a prenup, Ontario's default equitable distribution rules apply. Ontario divides property through "equalization of net family property" under the Family Law Act. Each spouse calculates the growth in their net worth during the marriage, and the spouse with the higher growth pays half the difference to the other. A prenup lets you define your own terms instead of leaving these decisions to state law or a judge's discretion.