Cohabitation Agreement Ontario: What to Include

What Is a Cohabitation Agreement?#

A cohabitation agreement is a domestic contract under Part IV of Ontario’s Family Law Act (FLA). It is an agreement between two people who are living together or who intend to live together, and who are not married to each other (FLA, s. 53(1)).

In practical terms, it works much like a prenuptial agreement but is designed specifically for unmarried couples. If the couple later marries, the cohabitation agreement is automatically treated as a marriage contract under the FLA (s. 53(2)), so the protections carry forward.

I find that many couples are surprised to learn this: in Ontario, common-law partners do not have the same automatic right to divide property that married spouses do. Married couples have equalization rights under Part I of the FLA. Common-law couples do not.

Who Should Get a Cohabitation Agreement?#

Not every couple moving in together needs a formal legal agreement, but a cohabitation agreement makes particular sense when:

• One partner owns a home and the other is moving in
• There is a significant difference in income or assets between the partners
• One partner owns a business or holds an interest in one
• Either partner has children from a previous relationship
• One partner plans to leave work or reduce hours to care for children or manage the household
• The couple is buying property together and wants to set out what happens if they separate

In my practice, the most common scenario involves one partner who owns a home. Without an agreement, disputes about whether the non-owning partner has a claim to the property (through a constructive trust or joint family venture) can lead to expensive litigation.

What a Cohabitation Agreement Can Cover#

Under FLA s. 53(1), a cohabitation agreement may address:

• Ownership and division of property (including the home, vehicles, investments, and personal belongings)
• Spousal support obligations (whether one partner will pay support if the relationship ends, and on what terms)
• Debt allocation (who is responsible for debts incurred during the relationship)
• The right to direct the education and moral training of children (though this is rarely exercised in practice)
• Any other matter in the settlement of their affairs

This is broad. Couples can structure the agreement to fit their circumstances, which is one of the reasons it is such a practical tool.

What It Cannot Cover#

There is one firm limit: a cohabitation agreement cannot determine decision-making responsibility or parenting time (FLA, s. 56(1)). Courts always retain jurisdiction over parenting arrangements based on the best interests of the child under the Children’s Law Reform Act. Any clause purporting to fix these issues will not bind the court.

A Practical Example#

Consider Anika and David. Anika owns a townhouse worth $620,000, with $380,000 remaining on the mortgage. David is moving in. He earns slightly less than Anika and has about $45,000 in savings.

Without a cohabitation agreement, David could potentially claim an interest in the townhouse if they separate years later, particularly if he contributes to mortgage payments, renovations, or household expenses. He would need to prove a constructive trust or unjust enrichment claim in court. That litigation is expensive for both sides and the outcome is uncertain.

With an agreement, Anika and David can specify that:

• The townhouse remains Anika’s sole property
• David will receive a defined credit for any direct contributions to the mortgage principal
• Spousal support will be addressed based on the length of cohabitation and any income disparity
• Joint purchases (furniture, a vehicle) will be divided according to a schedule attached to the agreement

Both walk away with clarity. If the relationship ends, the terms are already set. If it lasts, the agreement simply sits in a drawer.

Cohabitation Agreement vs. Marriage Contract vs. No Agreement#

The key difference: a marriage contract cannot waive rights to the matrimonial home. A cohabitation agreement can address the home more freely because the matrimonial home protections that apply to married spouses do not apply to unmarried partners. If the couple later marries, the agreement should be reviewed because matrimonial home rules will then apply.

What the Law Says: Enforceability and Setting Aside#

Formal Requirements (FLA, s. 55)#

For a cohabitation agreement to be enforceable in Ontario, it must be:

1. In writing
2. Signed by both parties
3. Witnessed

An oral agreement about property or support between common-law partners is not enforceable as a domestic contract.

Grounds to Set Aside (FLA, s. 56(4))#

A court may set aside a domestic contract or any provision in it if:

(a) A party failed to disclose significant assets, debts, or other liabilities existing at the time the contract was made

(b) A party did not understand the nature or consequences of the contract

(c) Otherwise in accordance with the law of contract (e.g., duress, unconscionability, misrepresentation)

These three grounds are the main vulnerabilities. Ontario courts have applied them consistently.

What the Cases Say#

The Supreme Court of Canada established the framework for reviewing domestic contracts in Miglin v. Miglin, 2003 SCC 24 at paras 80-91: first, whether the agreement was negotiated with substantially equal bargaining power; second, whether it still reflects the parties’ intentions and the objectives of the legislation at the time of the application.

The Court later reinforced in Rick v. Brandsema, 2009 SCC 10 at paras 44-49, that full and honest financial disclosure is required in negotiating domestic contracts.

At the appellate level, the Ontario Court of Appeal set aside an agreement for massive non-disclosure in LeVan v. LeVan, 2008 ONCA 388 at paras 46-55, where the husband disclosed his net worth at a figure far below reality. The case confirms that material non-disclosure engages s. 56(4)(a). And in Virc v. Blair, 2014 ONCA 392 at paras 23-30, the Court of Appeal held that while independent legal advice is not strictly required, its absence is a significant factor when assessing whether a party understood the consequences of a contract under s. 56(4)(b).

The pattern is consistent: agreements are much harder to challenge where there was proper disclosure, independent advice, and a fair process. For more on those safeguards, see our article on making marriage and cohabitation agreements stronger.

How to Make a Cohabitation Agreement Enforceable#

Based on the statutory requirements and the case law above, here is what I advise clients:

1. Full Financial Disclosure#

Both partners should exchange complete financial information before signing. This means a sworn financial statement or, at minimum, a detailed schedule listing all assets, debts, income, and liabilities. As LeVan and Rick v. Brandsema make clear, incomplete disclosure is the most common reason agreements are set aside.

2. Independent Legal Advice (ILA)#

Each partner should retain their own lawyer. While the FLA does not strictly require ILA for a cohabitation agreement to be valid, the absence of ILA makes the agreement far more vulnerable under s. 56(4)(b). In practice, I always recommend it. A certificate of independent legal advice from each lawyer should be attached to the agreement.

3. No Pressure or Rush#

Signing an agreement the night before moving in, or while one partner is in a vulnerable position, makes it easier for the other party to argue duress later. The agreement should be negotiated over a reasonable period, with both parties having time to review and ask questions.

4. Clear, Plain Language#

The agreement should be written so that a non-lawyer can understand it. Overly technical drafting can support an argument that one party did not understand the nature or consequences of what they signed.

5. Review and Update#

Circumstances change. I recommend that couples review their cohabitation agreement if there is a major life event: the birth of a child, a significant change in income, an inheritance, or the purchase of property together. An outdated agreement is harder to enforce than one that reflects current reality.

What Does a Cohabitation Agreement Cost?#

Costs vary by complexity and region, but as a general range in Ontario:

• Simple agreement (limited assets, straightforward terms): $2,500 to $4,000 per party, including ILA
• Moderate complexity (home ownership, investments, support provisions): $4,000 to $7,000 per party
• High complexity (business interests, multiple properties): $7,000 and up per party

These are rough Ontario ranges only and will vary significantly by lawyer, region, and complexity.

Compared to litigating property or support claims after separation — which can easily reach $30,000 to $100,000 or more — the upfront cost of an agreement is modest.

Frequently Asked Questions#

Next Steps#

If you are moving in with a partner or are already living together without an agreement, a cohabitation agreement is worth discussing with a family lawyer. The right agreement depends on the specific assets, income, and expectations involved.

To discuss whether a cohabitation agreement makes sense for you, contact our office to set up a consultation.