- Common-law couples in Ontario generally have no automatic right to equalization of property, unlike married spouses under the Family Law Act.
- A common-law partner seeking a share of property must generally rely on unjust enrichment or constructive trust claims — a far less predictable path than equalization.
- Ontario recognizes a couple as common-law for support purposes after three years of continuous cohabitation, or sooner if they have a child together and a relationship of some permanence.
- A cohabitation agreement can set out property division, spousal support terms, and debt responsibility in advance, filling the gap left by the law.
- If a common-law couple later marries, their cohabitation agreement is generally deemed to become a marriage contract under the Family Law Act.
- For the agreement to hold up, both partners generally need independent legal advice and full financial disclosure.
The Short Answer
No, a cohabitation agreement is not legally required to live with a partner in Ontario — but the legal reality it addresses is serious: common-law couples generally do not have the same automatic property rights as married spouses. Without an agreement, sorting out property after a common-law separation can be far more uncertain, expensive, and difficult than most people expect.
What “Common-Law” Actually Means in Ontario
For support purposes, Ontario's Family Law Act generally recognizes a couple as spouses once they have cohabited continuously for three years, or sooner if they have a child together and are in a relationship of some permanence. This threshold matters for support obligations — but it does not extend the same automatic property rights that apply to married spouses.
The Big Gap: No Automatic Property Rights
Married spouses in Ontario benefit from equalization of net family property — a formula-based sharing of the growth in each spouse's net worth during the marriage. Common-law partners have no equivalent automatic right, regardless of how long they lived together.
A common-law partner who contributed significantly to a home registered solely in the other partner's name — through money, labour, or otherwise — has no automatic legal claim to a share of it. Any claim generally has to be built through equitable doctrines like unjust enrichment or constructive trust, which require proving specific facts and are far less predictable than the equalization formula available to married spouses.
A couple lives together for eight years in a home registered solely in one partner's name. The other partner paid half the mortgage and renovation costs throughout the relationship but is not on title. Without a cohabitation agreement, that partner would need to bring a legal claim — likely unjust enrichment — to seek any share of the home's value, rather than simply relying on an automatic entitlement.
What a Cohabitation Agreement Can Cover
- How property owned before, and acquired during, the relationship will be divided or protected
- Responsibility for debts incurred individually or jointly
- Spousal support terms, including whether it will be paid and under what circumstances
- Treatment of a shared home, including contributions and eventual division if the relationship ends
- Gifts and inheritances, and how they will be protected or shared
Cohabitation Agreement vs. Marriage Contract
A cohabitation agreement and a marriage contract (commonly called a prenuptial agreement) serve the same essential purpose — setting out each partner's rights in advance — for different relationship statuses. Under the Family Law Act, if a couple with a cohabitation agreement later marries each other, that agreement is generally deemed to become a marriage contract, continuing to govern their affairs unless replaced with a new one.
What Makes It Enforceable
- Independent legal advice for each partner, from separate lawyers
- Full and honest financial disclosure from both sides
- A written, signed agreement, properly witnessed
- Fair terms, entered into voluntarily and without undue pressure
The same principles that protect a separation agreement or marriage contract from later challenge apply here — skipping independent legal advice or full disclosure to save money upfront significantly increases the risk the agreement won't hold up when it matters most.
What Happens Without One
Without a cohabitation agreement, a common-law separation involving disputed property generally requires the disadvantaged partner to bring a claim based on unjust enrichment or constructive trust — proving they made contributions that unfairly benefited the other partner, without adequate compensation. This is a genuine legal claim, but it is more complex, less predictable, and often more expensive to resolve than the equalization process available to married spouses.
When to Get One
A cohabitation agreement is worth considering whenever there is a meaningful imbalance in assets, income, or property between partners moving in together — or really, any time a couple wants clarity and protection rather than relying on general legal claims if things do not work out. It is easiest to negotiate before or early in cohabitation, but it remains available at any point in the relationship.
Common Mistakes
This is one of the most common and consequential misunderstandings in Ontario family law — property rights are genuinely different.
An informal understanding about property or contributions offers no real protection compared to a properly drafted, signed agreement.
A single lawyer cannot properly advise both partners — this significantly weakens the agreement's enforceability later.
Negotiating an agreement is far easier before a dispute arises than after — waiting until things are already tense makes it much harder to reach a fair, cooperative agreement.
Thinking about a cohabitation agreement, or dealing with a common-law property dispute? Call our Toronto family lawyers at 416-274-2222 for a free consultation.
Frequently Asked Questions
No, not for property purposes. While common-law partners can have support obligations similar to married spouses once they meet the legal threshold, Ontario's Family Law Act equalization of property regime — the automatic 50/50-style sharing of property growth during the relationship — generally applies only to married spouses, not common-law partners.
For support purposes under the Family Law Act, a couple is generally considered "spouses" after three years of continuous cohabitation, or sooner if they have a child together and are in a relationship of some permanence. This threshold relates to support, not property division rights, which work differently.
There is no automatic equalization. A common-law partner seeking a share of property they don't legally own must generally rely on equitable claims such as unjust enrichment or constructive trust, which require proving specific contributions and a resulting unfairness — a more complex, less predictable process than the equalization formula available to married spouses.
A cohabitation agreement is a contract between common-law partners, entered into before or during their relationship, that sets out how they will handle property, debts, and support if they separate — filling the legal gap left by the absence of automatic property rights for common-law couples.
Common terms include how property owned before and acquired during the relationship will be divided or protected, responsibility for debts, spousal support terms, treatment of a shared home, and how gifts or inheritances will be handled if the relationship ends.
Yes, generally. Under the Family Law Act, a cohabitation agreement is deemed to become a marriage contract if the parties to it later marry each other, continuing to govern their affairs unless they replace it with a new agreement.
It is strongly recommended, and in practice close to essential for the agreement to be enforceable. Each partner should generally receive independent legal advice from their own lawyer, along with full and honest financial disclosure from the other side.
Yes, in similar circumstances to a separation agreement or marriage contract — for example, where there was inadequate financial disclosure, the agreement is significantly unfair, or a party did not understand or was pressured into signing it.
No. While it is often easier to negotiate before moving in together, couples who are already cohabiting can still enter into a cohabitation agreement at any point during the relationship.
It depends on your specific situation, but even couples without significant assets can benefit from clarity around debt responsibility, contributions to shared expenses, and what happens to a shared home, particularly if one partner owns it and the other has contributed financially or through unpaid work over time.
You cannot force someone to sign an agreement, but their refusal is itself important information. If significant assets or financial imbalance are involved, it may be worth discussing why the agreement matters to you, or speaking with a lawyer about what legal protections remain available even without one.