If you’re moving in together in Ontario, it’s easy to assume “common-law” works like marriage. In reality, property ownership, debt responsibility, and spousal support can play out very differently, especially once you buy a home, share a mortgage, or combine finances.
A cohabitation agreement gives you a clear, written plan for what happens if the relationship ends, so you’re not relying on assumptions or scrambling to prove contributions later. In this 2026 guide, we’ll explain what a cohabitation agreement can (and can’t) do under Ontario family law, how to make it enforceable, and the practical clauses that protect both partners before big life decisions are made.
This guide is general information, not legal advice. If you want an agreement that actually holds up in litigation (and reduces the chance a family court judge sets it aside), we recommend a lawyer-drafted agreement with real financial disclosure and independent legal advice.
What is a cohabitation agreement in Ontario?
A cohabitation agreement in Ontario (sometimes called a living together agreement or domestic contract) is a written way for common-law partners to set clear rules about ownership, property rights, debt, and spousal support if there’s a relationship breakdown, separation, or even death. Ontario’s Family Law Act allows unmarried couples who are living together (or plan to start living together) to make a cohabitation agreement.
At RPB Family Law, we can help you turn that agreement into practical protection. We clarify what happens to the home, mortgage, joint accounts, and debts, build in fair support terms, and document proper financial disclosure and independent legal advice. Together, we can help make your cohabitation agreement clear, properly documented, and better positioned to withstand later disputes.
Cohabitation agreements, marriage contracts, and prenups in Ontario family law
A cohabitation agreement is closely related to a marriage contract (often called a prenuptial agreement, or prenup). In Ontario, a cohabitation agreement can be made “in contemplation of marriage,” and, if the parties marry, it can automatically become a marriage contract unless the agreement says otherwise.
- Cohabitation agreement: A domestic contract for common-law partners (or couples planning to live together) that sets rules for property ownership, debt, and spousal support if you separate.
- Marriage contract (prenup): A domestic contract for married spouses (or those about to marry) that sets financial terms for separation/divorce, often covering property and support, and protecting certain assets.
Why cohabitation agreements matter for property ownership, debt, and support
If you’re a common-law couple, the default rules can be surprising:
- You don’t automatically get an equalization payment like married spouses (Ontario equalization under the Family Law Act is for married spouses).
- Your property ownership may depend on whose name is on the title, who paid, and what can be proven, sometimes through claims like unjust enrichment, constructive trust, or resulting trust.
A strong cohabitation agreement reduces uncertainty around:
- the shared home (or any home you buy during cohabitation)
- mortgage payments and rent
- household utilities, furniture, vehicles, pets, and personal property
- shared finances like joint bank accounts
- debts: credit cards, lines of credit, and other liabilities
- support obligations (spousal support frameworks and limits)
Cohabitation agreements cannot override a child’s rights or predetermine parenting outcomes. Parenting (often discussed as access arrangements and child custody) is ultimately decided based on the child’s best interests under Ontario family law standards and statutes such as the Children’s Law Reform Act.
What is a Common-Law Spouse Entitled to in Ontario?
How to make a cohabitation agreement enforceable in Ontario
A cohabitation agreement is a domestic contract. In Ontario, it can be unenforceable if it isn’t in writing, signed by both partners, and witnessed (Family Law Act, s. 55).
Independent legal advice and full financial disclosure reduce risk
Even with proper signatures and a witness, an agreement can still be challenged later. The most common problems are:
- Incomplete financial disclosure: one partner didn’t fully disclose income, assets, or debts.
- Pressure at signing: claims of duress, coercion, or being rushed (for example, signing right before moving in or right before a major purchase).
- No independent legal advice (ILA): one or both partners didn’t get separate legal advice, or it wasn’t properly documented.
In plain terms: a strong agreement is not just a template with signatures. It’s a clear, written contract backed by full disclosure and separate legal advice, so it’s much harder to undo later.
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What to include in a cohabitation agreement: practical clauses that prevent fights
A high-performing Ontario cohabitation agreement is usually built around five modules:
1. Property ownership, assets, and business interests
- Define asset ownership (pre-relationship assets vs cohabitation assets)
- Address real property (home, cottage, condo)
- Address business interests and professional practices
- Set rules for “buyout,” sale, valuation, and appraisal process
2. Debts, finances and debts, and household responsibilities
- Allocate debt (credit cards, lines of credit, student loans)
- Define expense sharing: rent, utilities, groceries, insurance
- Address household responsibilities to reduce “who pays for what” conflict
- Specify how joint accounts are used (and when to close them)
Mortgage, lease, and utilities details (clauses people forget)
We often see agreements fail in practice because they never address:
- who makes mortgage payments during unemployment
- who gets reimbursed for principal paydown
- what happens if one person moves out but remains on the lease
- how utilities are split and tracked
3. Spousal support and child support obligations
A cohabitation agreement often includes spousal support terms:
- whether support is payable
- how support is calculated or limited
- review triggers (children, health events, income changes)
Courts can scrutinize support waivers, especially if the outcome is unconscionable in context, so we draft support clauses carefully and document informed consent.
4. Retirement plans: pension, CPP, survivor’s pension
If either partner has a workplace pension or defined contribution plan, clarify:
- what happens to post-cohabitation contributions
- disclosure expectations from a plan administrator
- how Canada Pension Plan credit splitting or retirement planning discussions fit into settlement (where relevant)
5. Estate planning: Will, estate, inheritance rights, intestate succession
Common-law partners can be shocked by “default” estate outcomes. A cohabitation agreement should not be treated as a substitute for a valid will, beneficiary-designation review, or estate-planning advice.
Important: estate outcomes are fact-specific; we coordinate domestic contracts and estate planning so the paperwork doesn’t conflict.
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What cohabitation agreements can’t do (and what they shouldn’t try to do)
Child support and parenting terms are limited
As noted above, you generally cannot contract out of a child’s rights. Agreements can express intentions, but a court can override terms that don’t align with best interests or lawful support obligations.
Education and moral training, residency arrangement, and access arrangements
People sometimes want to pre-set education, religion, or “residency arrangement” language. We can include intention statements, but we do not sell these as “binding custody clauses,” because courts retain authority.
Child Custody Agreement Without Court in Ontario
Our process at RPB Family Law: fast clarity, strong enforceability
At RPB Family Law, we build domestic contracts with an “enforceability-first” mindset:
Step-by-step cohabitation agreement process
- Intake + goals (home, mortgage, debt, support, estate planning)
- Full financial disclosure package (assets, liabilities, income)
- Draft agreement with plain-language explanations (so you understand what you’re signing)
- Independent legal advice coordination for both parties
- Formal signing with proper witnessing and document retention
- Annual/triggered review (home purchase, children, big income change)
Dispute resolution planning
We can include dispute resolution clauses (negotiation steps, mediation pathways) to reduce the chance of full-scale litigation during a relationship breakdown.
Why we don’t “guarantee” outcomes
No ethical family law team can promise that an agreement will never be challenged. What we can do is reduce the known risk factors: incomplete disclosure, lack of ILA, and poor drafting.
Should You Get Married in Canada?
Cohabitation agreements in Ontario | FAQs
Do we need to be living together already to draft a cohabitation agreement?
No. Ontario law allows couples who plan to live together (or already do) to enter into a cohabitation agreement.
Can a cohabitation agreement be turned into a marriage contract later?
Yes. If you marry, a cohabitation agreement can become a marriage contract unless stated otherwise.
Do common-law partners split property 50/50 in Ontario?
Not automatically. Common-law couples aren’t legally required to split property acquired while living together, unlike married spouses’ equalization regime.
Does a cohabitation agreement need a witness?
Yes, the Family Law Act formalities matter. Domestic contracts are unenforceable unless written, signed, and witnessed.
Can we decide child custody and child support in a cohabitation agreement?
You can include intentions, but you cannot remove a child’s rights or “lock in” parenting outcomes; courts decide based on best interests and lawful support principles.
Protect your home and your future before you move in
If you’re entering a common-law relationship, buying a home, sharing a mortgage, or blending finances and debts, a properly drafted cohabitation agreement is one of the clearest ways to reduce uncertainty and protect both partners.
If you want our family lawyers to draft or review your agreement, contact RPB Family Law, and we’ll help you build a document that’s practical, enforceable, and aligned with Ontario family law.
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