- A signed cohabitation agreement is not untouchable: Family Law Act s. 56(4) lets a court set aside all or part of it on specific grounds.
- The main grounds are failure to disclose significant assets or debts, not understanding the nature or consequences, and ordinary contract-law grounds.
- Courts can set aside one clause and leave the rest in place, so the outcome is often partial.
- Parenting terms cannot be enforced as agreed, and unreasonable child-support terms can be disregarded.
You signed a cohabitation agreement, and now the relationship is ending or you regret what you agreed to. Maybe you did not see your partner's full finances, or you signed quickly because a move or a wedding was coming. You want to know whether the agreement actually holds.
The short answer is that it depends on how it was made and what it says. Ontario courts can set aside an agreement, or a piece of one, but only on certain grounds. This article walks through those grounds in plain language.
When a cohabitation agreement is valid in the first place
Two people who are living together or plan to, and who are not married, can make a cohabitation agreement. It can cover rights and obligations while living together, when they stop living together, and on death, including ownership and division of property and support.
A domestic contract, which includes a cohabitation agreement, is unenforceable unless it is in writing, signed by the parties and witnessed. Ontario's guidance adds that each partner should use a different lawyer and exchange financial information.
If the basic formalities are missing, you may not need any of the grounds below. If they are present, the question becomes whether a ground to set the agreement aside applies.
The grounds to set an agreement aside under section 56(4)
Family Law Act s. 56(4) allows a court to set aside a domestic contract, or a provision in it, on three grounds.
| Ground | What it means in plain words |
|---|---|
| Non-disclosure | A party failed to disclose significant assets, debts or liabilities that existed when the contract was made. |
| Not understanding | A party did not understand the nature or consequences of the contract. |
| Contract-law grounds | Anything else that is a reason to undo a contract under the general law of contract, which includes duress, undue influence and unconscionability. |
Duress means being forced or pressured into signing. Undue influence means one person used a position of power over the other. Unconscionability means the deal was so one-sided and unfairly obtained that a court should not let it stand. Which of these fits depends heavily on the facts.
Partial results: one clause can go while others stay
A court does not have to throw out the whole agreement. In one Court of Appeal for Ontario decision, Moses Estate v. Metzer, 2017 ONCA 767, the court set aside the property clauses of a cohabitation agreement because neither party understood the consequences for their property venture, but left the spousal support waiver in place because there was no finding that the parties misunderstood it.
The lesson is that each provision can be looked at separately. Your complaint may succeed for one part and not another.
Terms a court may not enforce even if the agreement is valid
- Parenting terms: a cohabitation agreement cannot decide decision-making responsibility or parenting time for children. Those provisions cannot be enforced as agreed.
- Child support: a court may disregard a child-support provision that is unreasonable having regard to the child support guidelines.
- Support waivers: a court may set aside a support provision or waiver if it results in unconscionable circumstances, if the dependant qualifies for public support allowances such as social assistance, or if there is a default in payment when the application is made.
If the agreement was made outside Ontario, its essential validity and effect are governed by its proper law. Even so, s. 33(4) and s. 56 still apply in Ontario, and parenting-decision provisions are not enforceable in Ontario.
What to do next
- Find the signed original and confirm it was in writing, signed and witnessed.
- Gather any financial disclosure exchanged before signing, such as statements, schedules attached to the agreement, and emails listing assets and debts.
- Write down the timeline: when you first saw the agreement, how long you had to review it, and whether you had your own lawyer.
- Note what your partner owned or owed at signing that you were not told about, and how you learned of it.
- Note any pressure, threats or deadlines connected to signing.
- Do not delay getting legal advice, because the best argument may depend on which clauses you want to challenge.
A lawyer can read the agreement clause by clause and tell you which grounds, if any, realistically apply to your situation.
Frequently asked questions
Can I get out of a cohabitation agreement just because it is unfair?
Unfairness alone is not a listed ground. The court looks at non-disclosure, whether you understood the agreement, and contract-law grounds such as duress, undue influence and unconscionability. How unfair the result is may still matter to those arguments.
What if my partner hid a debt or asset when we signed?
A failure to disclose significant assets, debts or liabilities that existed when the contract was made is a ground to set aside the contract or a provision in it. Whether the missing item was significant is a question of fact.
Will the whole agreement be cancelled if I succeed?
Not necessarily. A court can set aside a provision rather than the whole contract, and in one Court of Appeal case property clauses were set aside while a support waiver stayed.
Can the agreement decide custody or parenting time?
No. A cohabitation agreement cannot decide decision-making responsibility or parenting time, and those provisions cannot be enforced as agreed.
Sources
- Ontario.ca – Dividing property when a marriage or common law relationship ends — ontario.ca
- Family Law Act, R.S.O. 1990, c. F.3 (e-Laws) — Ontario e-Laws
- Moses Estate v. Metzer, 2017 ONCA 767 (Court of Appeal for Ontario) — ontariocourts.ca
Links go to official government, court and regulator pages. The law changes — confirm you are reading the current version.
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