Can a marriage contract change how property is equalized in Ontario?

Yes. A valid marriage contract (sometimes called a prenuptial agreement) can modify many of the default equalization rules under the Family Law Act. Spouses can agree to exclude certain assets from net family property, specify how a particular asset will be treated, or even opt out of equalization entirely in favour of a different arrangement.

Marriage contracts can also address the matrimonial home — for example, allowing one spouse to deduct its pre-marriage value — though courts scrutinize such clauses carefully and may set aside an agreement that is grossly unfair or was signed without independent legal advice on both sides.

To be enforceable, a marriage contract must be in writing, signed by both parties, and witnessed. Courts can set aside a contract if a spouse did not disclose significant assets, if a party signed under duress or did not understand it, or if the agreement is unconscionable. Speaking with a family law lawyer before signing any marriage contract is strongly advised.