Setting aside a marriage contract or separation agreement

An Ontario court can set aside all or part of a marriage contract or separation agreement if a party hid significant assets or debts, did not understand the contract, or the contract fails under ordinary contract law (Family Law Act, s. 56(4)). Support terms can also be overridden if they lead to unconscionable circumstances. Proving a ground is not enough on its own: the judge still decides whether to set it aside.

How does a challenge to a domestic contract work in Ontario?

The Family Law Act calls these agreements "domestic contracts". The term covers marriage contracts (what many people call a prenup), cohabitation agreements, separation agreements, paternity agreements and family arbitration agreements (s. 51). A valid contract generally wins over the Act: section 2(10) says a domestic contract dealing with a matter in the Act prevails unless the Act says otherwise. So the starting point is that the deal you signed stands. Our property division page explains what happens when there is no contract at all.

A challenge usually follows these steps:

Check the form. A domestic contract is unenforceable unless it is in writing, signed by both parties and witnessed (s. 55(1)). An unwitnessed or unsigned document fails at this first step.
Identify which clauses you are attacking. Property, spousal support, child support and parenting terms each have their own test. A court can set aside "a provision" as well as the whole contract.
Rebuild what happened at signing. What financial information was exchanged, whether each side had a lawyer, how much time there was to review the deal, and whether anyone was under pressure.
Choose the right court. If property is involved, the case goes to the Superior Court of Justice, because the Ontario Court of Justice cannot hear property claims under Part I of the Act (s. 4(1)). In Toronto, Superior Court family matters are heard at 361 University Avenue.
Bring the application and claim what you want in its place. If the contract falls, the court applies the Act instead, so the case usually also asks for equalization, support or both.
Watch the property deadlines. An equalization claim must be started within two years after a divorce or six years after separation, whichever comes first (s. 7(3)), unless the court extends the time (s. 2(8)).

The deadline rules are covered in our page on property deadlines in Ontario.

The grounds, side by side

Ground	What it covers	Where it comes from
Wrong form	Not in writing, not signed by both, or not witnessed	Family Law Act, s. 55(1)
Non-disclosure	A party failed to disclose significant assets, debts or other liabilities that existed when the contract was made	s. 56(4)(a)
No real understanding	A party did not understand the nature or consequences of the contract	s. 56(4)(b)
Contract law	Grounds such as unconscionability, as in Rick v. Brandsema	s. 56(4)(c)
Spousal support terms	A support term or waiver leads to unconscionable circumstances, the dependant qualifies for support from public money, or support is in default	s. 33(4)
Child support terms	The term is unreasonable having regard to the child support guidelines	s. 56(1.1)
Parenting terms	The court may disregard a term if that is in the child's best interests	s. 56(1)
Matrimonial home rights	A marriage contract term that limits rights under Part II, such as possession of the home, is unenforceable	s. 52(2)
Religious barriers	Removing barriers to the other spouse's remarriage within their faith was part of the bargain	s. 56(5)

Section 56(7) says the setting-aside powers in subsections (4) to (6) apply "despite any agreement to the contrary". A clause saying neither party will ever challenge the contract does not shut the door.

Non-disclosure: what counts

Most challenges start here. The Court of Appeal for Ontario looked at this ground closely in LeVan v. LeVan, 2008 ONCA 388. Two points from that decision matter most in practice.

First, listing an asset is not always enough. The husband in LeVan named his interests in family companies and a family trust but gave no values, no financial statements and no tax returns. The court upheld the finding that he had not met the disclosure duty, and it found no support for the idea that a bare list of significant assets, with no indication of value, satisfies section 56(4)(a). The court also endorsed the view that a party must know what assets and debts exist, and understand the legal scheme, to know what they are giving up.

Second, the analysis has two stages. Proving a ground under section 56(4) does not automatically cancel the contract. The judge then decides, as a matter of discretion, whether setting it aside is appropriate. At that stage the court may consider the fairness of the contract, whether the non-disclosure was deliberate, and whether the other party had effective legal advice. A clearly unfair contract is more likely to be set aside than a fair one.

Our page on financial disclosure in a property case explains what full disclosure looks like once a case is in court.

Separation agreements and support releases

Separation agreements are signed at a hard time, and the Supreme Court of Canada has said so. In Rick v. Brandsema, 2009 SCC 10, the Court held that separating spouses have a duty to make full and honest disclosure of all relevant financial information while negotiating. Where one spouse exploits the other's vulnerabilities, or hides or undervalues assets, and the result departs substantially from the objectives of the governing law, the agreement may be found unconscionable and unenforceable. Having lawyers can make up for a vulnerability, but not always. An agreement negotiated with full and honest disclosure and without exploitation will likely survive.

Spousal support terms get a further layer of review. For married couples who divorce, the Divorce Act tells the court to consider any agreement about support (s. 15.2(4)(c)). In Miglin v. Miglin, 2003 SCC 24, the Supreme Court set a two-stage approach:

At signing: was there oppression, pressure or another vulnerability, and how much professional help did each side have? Did the terms substantially comply with the objectives of the Divorce Act when made?
Now: does the agreement still reflect what the parties intended, and does it still substantially comply with those objectives? The person challenging it must show new circumstances that were not reasonably anticipated. Changes in health, jobs, housing and asset values are treated as foreseeable.

If the agreement was fair when signed but life has changed, the better question may be whether support can be varied. See our page on changing spousal support.

What changes the answer

Independent legal advice. The Act does not require it, but its absence matters. In LeVan, the lack of effective advice was one of the reasons the trial judge exercised her discretion to set the contract aside, and Miglin treats professional help as able to offset an imbalance.
Size of what was hidden. Section 56(4)(a) speaks of "significant" assets, debts or other liabilities. Leaving out a small account is treated differently from leaving out a business.
The kind of term. Property terms are tested under section 56(4). Child support terms can be disregarded if unreasonable under the guidelines (s. 56(1.1)), and parenting terms can be disregarded in the child's best interests (s. 56(1)). A marriage contract cannot settle decision-making responsibility or parenting time at all (s. 52(1)(c)).
Excluded property. A contract can keep property out of net family property (s. 4(2), para. 6). If that clause is set aside, the property counts again. Our page on excluded property explains the other exclusions that apply without a contract.
The family home. Part II rights cannot be limited by a marriage contract (s. 52(2)), so a clause giving up possession rights in the matrimonial home is unenforceable from the start.
Contracts signed elsewhere. A contract made outside Ontario is still subject to sections 33(4) and 56 here (s. 58(b)).
Unmarried couples. A cohabitation agreement faces the same tests. If it falls, the couple uses common-law claims rather than equalization; see our page on unjust enrichment claims.

A worked example

For example, imagine a hypothetical couple, Taylor and Morgan, who signed a marriage contract a few days before their wedding. The contract excluded Taylor's shares in a family company from net family property. Taylor's disclosure schedule named the company but gave no value. Morgan saw a lawyer once, briefly, and signed.

Years later they separate. The shares were worth $100,000 on the wedding day and $900,000 on the valuation date. If the clause stands, the shares are left out entirely. If a court sets the clause aside, the shares count in Taylor's net family property, less the $100,000 they were worth at the wedding, so $800,000 is added to Taylor's side. Because equalization is half the difference between the spouses' figures, Morgan's payment would rise by $400,000, all else being equal.

Whether the clause falls depends on both stages: did Taylor fail to disclose a significant asset under section 56(4)(a), and, if so, should the judge exercise the discretion to set it aside, given the advice Morgan had, the timing and the fairness of the deal? This example shows the stakes; it does not predict any result.

Common mistakes with domestic contracts

Disclosing a list instead of values. LeVan shows that naming an asset with no indication of its worth can leave a contract open to challenge.
Signing on the eve of the wedding. Pressure and lack of time are part of the first stage of the Miglin analysis and of the discretion under section 56(4).
Using one lawyer for both people. Each party needs advice that is their own, so they understand what they are giving up.
Assuming a "no challenge" clause protects the deal. Section 56(7) says otherwise.
Waiting to challenge. If the contract is set aside, you still need a valid equalization claim, and the time limits in section 7(3) keep running.
Relying on an unwitnessed copy. Without a witness, a domestic contract is unenforceable under section 55(1).

What to do this week

Find the signed contract and every schedule, draft and covering email.
Check the last page: are both signatures there, and is each one witnessed?
List every asset and debt each of you had on the signing date, and mark anything missing from the disclosure.
Write down when you first saw the contract, when you signed it, and who advised you.
Note the date you separated, and any divorce date, so the equalization deadlines can be checked.
Read our overview of when a marriage contract makes sense if you are deciding whether to sign a new one.
Book a free consultation to have the contract reviewed against section 56(4).

Frequently asked questions

Can a marriage contract that seems unfair be set aside just because it is unfair?

Unfairness alone is not one of the grounds in section 56(4). In LeVan, the Court of Appeal said fairness can be weighed at the second, discretionary stage, once a statutory ground is proven. Support terms are different: section 33(4) allows a court to set aside a support provision that results in unconscionable circumstances.

Does it matter that I had a lawyer when I signed?

It often helps the contract survive, because the court can see you were told what you were giving up. It is not conclusive. In Rick v. Brandsema, the Supreme Court accepted that a spouse's vulnerability left her unable to use the help that was available.

Can a separation agreement be filed with the court?

Yes. A party can file a domestic contract with the clerk of the Ontario Court of Justice or the Family Court of the Superior Court of Justice, with an affidavit that it is in effect (s. 35(1)). Support terms in a filed contract can then be enforced like an order. Section 33(4) still applies to a filed contract (s. 35(3)).

What happens to the rest of the agreement if one clause falls?

Section 56(4) lets the court set aside a single provision or the whole contract. The rest can survive. Miglin also notes that even a term that is not fully enforceable may still show what the parties intended.

If the contract is set aside, will the court divide everything equally?

The ordinary rules of the Family Law Act apply. For married spouses that means equalizing net family property, with a narrow power to order a different amount where equal sharing would be unconscionable (s. 5(6)). Our page on unequal division explains that test. Our guide to how property is divided walks through the full calculation.

Can a parent sign away child support?

A court can disregard a child support term that is unreasonable having regard to the child support guidelines (s. 56(1.1)). Under the Divorce Act, a court can approve a different amount on consent only if reasonable arrangements have been made for the child (s. 15.1(7)).

When can a marriage contract or separation agreement be set aside in Ontario?