What Is a Cohabitation Agreement?
A cohabitation agreement is a type of domestic contract recognized under Ontario's Family Law Act. It is generally available to two people who are living together, or who intend to live together, and who are not married to each other. Within that agreement, partners can set out their own rights and obligations toward one another — both while they are living together and if the relationship later ends.
Unlike a court order, a cohabitation agreement is a private contract the partners create for themselves. It does not require a judge, a court application, or even a lawyer to sign — although, as explained below, certain formalities must be followed for it to be enforceable.
Who Should Consider a Cohabitation Agreement
A cohabitation agreement can be useful for any couple planning to move in together, whether or not marriage is part of the plan. It tends to come up most often for couples where:
- One or both partners own significant property, a business, or investments before moving in together.
- One partner is bringing substantially more debt, income, or assets into the relationship than the other.
- A couple wants clarity about how a shared home, renovations, or major purchases will be treated.
- One or both partners have children from a previous relationship and want to protect assets intended for them.
- A couple simply wants to avoid uncertainty about their legal rights, rather than leaving those questions to be resolved later if the relationship ends.
There is no rule that a cohabitation agreement must be signed before moving in together — a couple already living together can sign one at any time, though signing before or shortly after moving in is common.
Why a Cohabitation Agreement Matters More for Common-Law Partners
A cohabitation agreement tends to carry more weight for common-law partners than a similar agreement does for married spouses, because of how differently Ontario law treats the two groups when it comes to property. Married spouses may be entitled to an automatic equalization of net family property when the marriage ends. Common-law partners generally have no equivalent automatic right, no matter how long they lived together or how they organized their finances.
Without a cohabitation agreement, a common-law partner who is not on title to a shared home or other asset generally has no automatic claim to it, and may need to rely on more complex, fact-specific legal doctrines such as unjust enrichment to seek any share at all. A cohabitation agreement lets partners decide these questions for themselves in advance, rather than leaving them to be reconstructed later from years of financial records. For a fuller explanation of how property rights differ for unmarried couples, see our guide to common-law relationships in Ontario and common-law property rights.
What a Cohabitation Agreement Can Address
Within the limits described below, partners generally have wide flexibility to decide what goes into their agreement. Common subjects include:
- Ownership of property brought into the relationship, and how it will be treated if the relationship ends.
- How property acquired during the relationship will be divided, including a home, vehicles, or investments.
- Responsibility for debts, both those brought into the relationship and those taken on together.
- Whether spousal support will be paid if the relationship ends, and on what terms.
- How shared expenses and contributions will be handled while the couple is living together.
- What happens to specific assets, such as a family business, an inheritance, or a home owned before the relationship began.
A cohabitation agreement generally cannot decide parenting time, decision-making responsibility, or child support for children of the relationship — those issues are decided based on the best interests of the child at the relevant time, not by private agreement between the parents.
Formality Requirements
Like other domestic contracts in Ontario, a cohabitation agreement generally must be in writing, signed by both partners, and witnessed to be enforceable. A verbal understanding, even a detailed one, is generally not enforceable as a domestic contract under the Family Law Act.
Beyond the basic formalities, courts also expect a degree of fairness in how the agreement was reached. An agreement may later be open to challenge if a partner did not provide honest and complete financial disclosure, did not understand what they were signing, or did not enter into it voluntarily — for example, if they were pressured shortly before signing. These same general principles apply if partners later want to amend or cancel their agreement: an amendment or cancellation is generally unenforceable unless it, too, is in writing, signed, and witnessed.
What Happens If You Later Marry?
A commonly cited rule under Ontario's Family Law Act is that if the parties to a cohabitation agreement later marry each other, the agreement is generally deemed to continue in effect as a marriage contract, unless the agreement itself provides otherwise. In practical terms, this means a couple's existing cohabitation agreement does not automatically disappear on the wedding day — it can carry forward and continue to govern the same property and support questions, now as between spouses rather than common-law partners.
Because this outcome is the default, couples who want their agreement to stop applying once they marry, or who want different terms once married, generally need to say so explicitly in the agreement, or sign a new one before or after the wedding. Anyone relying on this rule for a specific agreement should confirm its effect with a qualified professional, since the precise wording of an individual contract can affect how it applies after marriage.
Cohabitation Agreement vs. Marriage Contract
Cohabitation agreements and marriage contracts are close cousins under Ontario law, and, as just explained, one can turn into the other. The main practical difference is who each is for: a cohabitation agreement is available to partners who are not married to each other, while a marriage contract (sometimes called a prenuptial or postnuptial agreement) is for partners who are already married or are about to marry. The subjects they can address — property, debt, and support — generally overlap a great deal, and both are subject to the same formality rules described above. For a closer look at how marriage contracts work on their own, see our guide to marriage contracts in Ontario.
Independent Legal Advice
Independent legal advice — each partner speaking with their own separate lawyer rather than sharing one — is not a strict legal requirement for a cohabitation agreement to be signed. It is, however, widely recommended, because a court reviewing the agreement later may look at whether each partner actually understood what they were agreeing to and had a fair opportunity to get advice before signing. An agreement signed without independent legal advice can still be enforceable, but it may be more vulnerable to challenge, particularly where the partners' financial positions were very different. Read more about independent legal advice and why it matters for domestic contracts generally.