- A court may set aside a domestic contract or a provision in it on specific grounds.
- The grounds include non-disclosure of significant assets or debts, not understanding the contract, and ordinary contract law grounds.
- A domestic contract is unenforceable unless written, signed and witnessed, so formalities are the first thing to check.
Signing a prenup or separation agreement can feel final, and some people later regret it. Ontario law does allow challenges, but only on particular grounds.
This article explains the grounds, what the formal requirements are, and how to think about your options. Whether a challenge works depends heavily on the facts, so a lawyer should review your documents.
What counts as a domestic contract
Domestic contracts include marriage contracts, separation agreements, cohabitation agreements, paternity agreements and family arbitration agreements. A domestic contract that deals with a matter also covered by the Family Law Act prevails, unless the Act provides otherwise. That is why challenging one matters: if it stands, it usually replaces the default rules.
What these contracts can cover
Two people who are married or intend to marry may agree on their rights and obligations under the marriage or on separation, annulment or death. That includes ownership in or division of property, support, the right to direct the children's education and moral training, and any other matter in the settlement of their affairs.
- A marriage contract is made by people who are married or intend to marry.
- A separation agreement is made by two people who cohabited and are living separate and apart, and it can deal with ownership in or division of property.
- A cohabitation agreement is deemed to be a marriage contract if the parties marry each other.
A separation agreement can release a spouse's matrimonial home rights, which allows a later sale or mortgage without that spouse's consent. A marriage contract can also exclude the home's value from net family property. Common-law couples are not legally required to split property acquired while living together, so a written agreement may matter even more for them.
The grounds for setting one aside
On application, a court may set aside a domestic contract or a provision in it on the following grounds:
| Ground | In plain words |
|---|---|
| Non-disclosure | A party failed to disclose significant assets, or significant debts or other liabilities, that existed when the contract was made. |
| No understanding | A party did not understand the nature or consequences of the contract. |
| Contract law | Other grounds under the law of contract, such as duress, undue influence, misrepresentation or unconscionability. |
In plain terms, the first ground looks at what was known when the contract was signed: were important assets or debts left out? The second looks at whether you grasped what you were agreeing to. The third lets a court apply ordinary contract principles. Which one fits, if any, depends on the facts and the documents.
The court may set aside the whole contract or only a provision. Courts also have a separate power over separation agreements where a party has not taken steps within their control to remove barriers to the other party's remarriage within their faith.
Check the formalities first
A domestic contract, and any agreement to amend or rescind it, is unenforceable unless it is made in writing, signed by the parties and witnessed. If one of those steps is missing, that may be a starting point for a challenge.
The Ontario government also advises that each partner use a different lawyer and exchange financial information before signing. Records of what was disclosed and what advice each person received are worth gathering, because they relate directly to the grounds of non-disclosure and not understanding the contract.
Parts a court may disregard anyway
Some terms are not fully in the parties' hands. A court may disregard a provision on education, moral training, decision-making responsibility or parenting time where that is in the child's best interests, and may disregard a child support provision that is unreasonable having regard to the child support guidelines.
A marriage contract or cohabitation agreement cannot decide decision-making responsibility or parenting time. A marriage contract provision that limits a spouse's matrimonial home possession and consent rights is unenforceable.
What to do next
- Find the signed contract and any drafts, and check whether it was in writing, signed and witnessed.
- Gather the financial information that existed when you signed, and compare it with what was actually disclosed.
- Write down who advised each of you, what was explained, and the circumstances of signing.
- Avoid acting on the agreement in ways that could complicate things before you get advice.
- How timing affects your options depends on your situation, so it is worth confirming with a lawyer early.
Bring the whole picture to your first meeting: the contract, any financial statements or disclosure you received, messages from around the time of signing, and a timeline of key dates. A lawyer can assess which ground, if any, fits your facts and what a court might do. Each case turns on its own facts, so no outcome can be assumed.
Frequently asked questions
Can I set aside a prenup just because I regret it?
Regret alone is not a listed ground. The grounds are non-disclosure of significant assets or debts, not understanding the contract's nature or consequences, or contract law grounds such as duress or undue influence. A lawyer can tell you whether your facts fit any of them.
Does the whole agreement have to be set aside?
Not necessarily. A court may set aside a domestic contract or a provision in it. Which approach applies depends on the facts.
What if the agreement was not witnessed?
A domestic contract is unenforceable unless it is in writing, signed by the parties and witnessed. A lawyer can tell you how that affects your case.
Can a court ignore what the agreement says about the children?
Yes, in some respects. It may disregard provisions on education, moral training, decision-making responsibility or parenting time where that is in the child's best interests, and unreasonable child support terms. Whether that applies to your agreement depends on its wording and your children's circumstances.
Sources
- Family Law Act, R.S.O. 1990, c. F.3, ss. 2(10), 51 (e-Laws) — Ontario e-Laws
- Ontario.ca – Dividing property when a marriage or common law relationship ends — ontario.ca
Links go to official government, court and regulator pages. The law changes — confirm you are reading the current version.
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