A Canadian Marriage Contract, commonly known as a prenuptial agreement, is a domestic contract between two people who are married or intend to marry. The legal terminology varies by province: in Ontario, the Family Law Act (R.S.O. 1990, c. F.3, s. 52) formally calls it a "marriage contract," while British Columbia's Family Law Act (S.B.C. 2011, c. 25) uses "marriage agreement," and Alberta's Family Property Act (S.A. 2003, c. F-4.7) refers to "agreements" between spouses. Regardless of the label, the purpose is the same: the parties define their rights and obligations regarding property, support, and finances during the marriage and in the event of separation or divorce.

The enforceability of marriage contracts in Canada is governed by both provincial family law statutes and the federal Divorce Act (R.S.C. 1985, c. 3 (2nd Supp.)). The Supreme Court of Canada established the framework for reviewing domestic contracts in Hartshorne v. Hartshorne (2004 SCC 22), holding that courts should generally respect the parties' autonomy to structure their own affairs, but may intervene where the agreement is unconscionable or where one party failed to make adequate financial disclosure. In Miglin v. Miglin (2003 SCC 24), the SCC set out a two-stage test for reviewing spousal support provisions in domestic contracts, balancing respect for the parties' intentions against the possibility that circumstances have changed materially.

Unlike American prenuptial agreements, Canadian marriage contracts operate within a system where each province has distinct default property division rules. In Ontario, the default regime is equalization of net family property (FLA s. 5), meaning each spouse calculates their net family property and the spouse with the higher amount pays half the difference to the other. In British Columbia, the default is equal division of family property (FLA s. 81). A marriage contract allows the parties to modify, expand, or contract these default rules, subject to the statutory limitations discussed below.

A Canadian Marriage Contract is essential when one or both parties bring significant pre-marital assets into the marriage and want to protect them from equalization or division. In Ontario, the growth in value of pre-marital assets during the marriage is included in net family property for equalization purposes (FLA s. 4(1)) unless excluded by a domestic contract. Without a marriage contract, a spouse who owned a business worth $500,000 before marriage could owe equalization on the increase in the business's value during the marriage.

This contract is critically important for business owners. Without a prenuptial agreement, a spouse may be entitled to share in the value of the other spouse's business upon separation. A marriage contract can exclude the business entirely, limit the claim to the increase in value during the marriage, or establish a predetermined valuation method. This avoids costly and disruptive business valuations during separation proceedings.

Parties with children from previous relationships need a marriage contract to protect their children's inheritance expectations. The contract can ensure that certain assets pass to the children of a prior relationship rather than being subject to equalization with the new spouse. Parties with significant family wealth, trusts, or expected inheritances should also consider a marriage contract to clarify the treatment of gifts and inheritances during the marriage.

A marriage contract is also advisable when the parties have significantly different income levels or when one party will be giving up career opportunities to support the household. The contract can establish fair spousal support provisions that reflect the parties' actual circumstances, rather than relying on the uncertainty of court-determined support.

A valid Canadian Marriage Contract must be in writing, signed by both parties, and witnessed. In Ontario, Family Law Act s. 55(1) requires that domestic contracts be in writing, signed, and witnessed to be enforceable. The contract must identify both parties with their full legal names, dates of birth, addresses, and occupations. The date of marriage (or intended marriage) must be stated.

Full and frank financial disclosure is the single most important element for enforceability. Each party must disclose all significant assets (with approximate values in Canadian dollars), debts and liabilities, and annual income. Courts routinely set aside marriage contracts where a party concealed or undervalued assets. The disclosure should be detailed enough that each party can make an informed decision about the contract's terms.

The property provisions must address: (1) pre-marital property and whether it is excluded from division; (2) property acquired during the marriage and how it will be divided upon separation; (3) the matrimonial home, including ownership, possession rights, and disposition upon separation (noting that in Ontario, the right to possession of the matrimonial home cannot be waived by contract under FLA s. 52(2)); (4) gifts and inheritances; and (5) business interests, if applicable.

Spousal support provisions should state whether the parties waive or agree to support, and the terms of any agreed support. Note that courts retain jurisdiction to review support waivers under the Miglin v. Miglin framework. Debt allocation provisions should address both pre-marital debts and debts incurred during the marriage. Independent legal advice for each party is strongly recommended and significantly strengthens enforceability. Include a dispute resolution clause specifying mediation, arbitration, or litigation. The governing law clause should reference the applicable Canadian province.