Do prenups work in Ontario? The short answer is a resounding yes– as long as you follow the laws required by your province. However, if you do not follow your province’s laws then you could be looking at a contract that doesn’t “work.” Below, we discuss all of the things you need to know about making your prenup work and some real case law showing prenups being successfully upheld in real life.
What makes a prenup enforceable in Ontario?
There are certain laws you must follow in order for your prenup to be valid and enforceable. Each province has its own rules, so it’s important to follow your province’s laws. In Ontario, here’s what makes a prenup enforceable:
- The prenup is in writing
- Both parties sign the prenup
- The prenup is witnessed by one person who is not a party to the contract
- The parties must provide one another with financial disclosure
Independent legal advice (ILA) is not strictly required, but the lack of legal advice can lead to a court setting aside an agreement.
When do prenups not work?
Are there any scenarios where prenups don’t “work?” Great question! Yes, there are a few scenarios where a prenup may not work. Here’s what to know. A prenup may not work if…
- You don’t put it in writing and only verbally agree to terms
- You don’t properly execute the document (no signatures and/or witnesses)
- You don’t accurately disclose financial information to your partner
- The terms of the agreement are overly unfair (leaving one person destitute, for example)
- There was duress or coercion present in the formation of the prenup
- There was a lack of legal advice, and this absence negatively affected one of the parties
Do I need a lawyer for a prenup to work in Ontario?
Technically, no, but the absence of a lawyer during the prenup formation process can be a reason that a court sets aside an agreement. The court will look at the situation on a case-by-case basis to determine if the lack of independent legal advice was detrimental to the person who is challenging the agreement. Plus, with the assistance of independent legal advice, you have other benefits such as peace of mind, a tailored contract, and all your questions answered.
How do you enforce a prenup in a divorce?
When a couple with a prenup decides to separate, the agreement becomes a key part of the legal proceedings. Depending on the terms within the prenup, it might be as straightforward as transforming it into a separation agreement that both parties sign. The separation agreement is then incorporated into the final divorce document. However, since prenups cannot include terms around child support and custody, the couple will still need to figure those aspects out. Having a prenup helps the couple focus on these outstanding issues and have property matters already settled.
Cases where prenups were successfully upheld in Ontario
Here are some real-life examples that show how domestic contracts have “worked” in real life. The below are court opinions successfully upholding these agreements in Ontario.
Anderson v. Anderson, 2023 SCC 13
A couple signed off on a separation agreement that they created on their own without independent legal advice or financial disclosure. They had two friends witness them sign the agreement. The agreement stated they would each keep their own separate property and waive any right to the other’s property. In addition, they would share the home and home goods. The husband later argued the agreement was signed under duress and without legal advice and asked the court to throw it out.
The result? The court enforced the contract and divided the property according to its terms. It underscored the importance of the freedom to contract and that domestic agreement should be encouraged by courts. And while this wasn’t a prenup, per se, it still is a domestic contract and the underlying notion is that courts favor domestic agreements, including prenups.
Singh and Khalil, 2024 ONCA 909

The parties in Singh v. Khalil, 2024 ONCA 909 married in 2016 and separated in 2020. In 2017, the wife drafted a marriage contract stipulating no spousal support obligations and all separate property. The husband signed the contract in the presence of a lawyer but chose not to seek independent legal advice. He later sought to set aside the agreement, alleging duress and lack of disclosure.
The result? The court rejected these arguments and found the marriage contract was valid, noting the husband’s extensive legal experience and capacity to understand contracts. The court highlighted the proportionality principle under the Family Law Rules, which supports resolving matters efficiently in line with their complexity.
Oliver v. Coderre, 2021 ONSC 4102 (CanLII)
This case involves a husband and wife who signed a cohabitation agreement before they were married. The husband later sought to have the agreement set aside, but the court ultimately upheld the agreement.
The agreement was upheld for several reasons, including:
- The husband was found to have understood the nature and consequences of the agreement, despite his claims to the contrary.
- There was no evidence of material lack of disclosure.
- There was no evidence of unconscionability, undue influence, duress, or misrepresentation.
- The agreement clearly defined both real property and one-party property, and the failure to specifically define the matrimonial home did not void the contract.
- The agreement was deemed to be a marriage contract when the parties married.
- The court also dismissed the husband’s claim that the spousal support provisions in the agreement should be set aside.
The bottom line is that prenups do work in Ontario, Canada
In conclusion, prenuptial agreements are indeed effective in Ontario and throughout Canada. By adhering to provincial legal requirements and seeking guidance from a qualified lawyer, you can create a prenup that safeguards your financial interests and provides you with peace of mind. As demonstrated by the real-life case law above, domestic contracts such as prenups offer valuable protection and clarity for couples.

Anna-Marie Musson is a Family Lawyer with over 20 years’ experience. A graduate of Windsor Law, Anna-Marie began practising in 2003. She was a partner at a prominent national Bay Street law firm before starting her own firm. Anna-Marie helps professionals and high net worth clients navigate the financial, emotional, and legal issues in divorce and separation. She also helps clients preserve their net worth and avoid financial ruin with Marriage Contracts (Pre-nups) and Cohabitation Agreements. Anna-Marie is the host of the Modern Divorce Show on 105.9 The Region and also hosts the upcoming Podcast – Love & Wealth.

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