Can a Spousal Support Waiver Be Overturned Later? Understanding the Miglin Analysis

Separating spouses often enter into separation agreements or marriage contracts that include a waiver of spousal support. These provisions are frequently intended to provide certainty, finality, and closure. However, many people are surprised to learn that a spousal support waiver is not always the end of the story. 

In certain circumstances, Ontario courts can set aside or override a spousal support waiver years after it was signed. Whether a waiver will be enforced depends on several factors, including how the agreement was negotiated, whether sufficient financial disclosure was provided, and whether the agreement continues to reflect the parties’ intentions and the objectives of Canadian family law. 

The leading case in this area is the Supreme Court of Canada’s decision in Miglin v. Miglin, 2003 SCC 24. 

The General Rule: Courts Respect Agreements 

Canadian family law generally encourages parties to resolve their disputes through negotiated agreements. Courts recognize that separating spouses are usually in the best position to make decisions about their financial futures. 

As a result, a properly negotiated spousal support waiver will often be upheld. However, the courts must also ensure that agreements are fair and consistent with the objectives of the Divorce Act and Ontario’s Family Law Act. When a waiver produces an unfair result or was negotiated under problematic circumstances, judicial intervention may be justified. 

The Miglin Test Under the Divorce Act 

When a claim for spousal support is brought under the Divorce Act, courts typically apply the two-stage framework established in Miglin. 

Stage One: What Were the Circumstances When the Agreement Was Signed? 

The court first examines the negotiation and execution of the agreement to determine whether there is any reason to discount the parties’ bargain. 

Some of the factors considered include: 

• Whether there was pressure, coercion, or exploitation of a vulnerable spouse; 

• Whether there was a significant imbalance of bargaining power; 

• Whether the parties had independent legal advice; 

• Whether there was meaningful financial disclosure; 

• The length and nature of the negotiations; and 

• The roles and circumstances of the parties during the relationship. 

The court will also consider whether the agreement substantially complied with the objectives of the Divorce Act, including: 

• Recognizing economic advantages and disadvantages arising from the marriage; 

• Sharing the financial consequences of child-rearing; 

• Relieving economic hardship caused by the breakdown of the marriage; and 

• Promoting economic self-sufficiency where practical.

A waiver is more likely to be upheld where the parties entered into the agreement knowingly, voluntarily, and with adequate information. 

Stage Two: Does the Agreement Still Reflect the Parties’ Original Intentions? 

Even where an agreement was properly negotiated, a court must consider whether subsequent events have caused the agreement to operate in a way that the parties never contemplated. 

The test is not strict foreseeability, but rather whether the change or emerging situation was contemplated when the agreement was negotiated. The change does not need to be “radically unforeseen” or causally connected to the marriage. However, courts emphasize that although the future is uncertain, it is reasonably anticipated that changes will occur in the job market, parenting responsibilities, difficulty transitioning into the workforce, health changes, and inflation. The change must be a significant departure from the parties’ intentions to warrant overturning a spousal support waiver. 

Where a Claim is Brought Under the Family Law Act  

Section 33(4): Unconscionable Circumstances 

Even where an agreement itself remains valid, a court may override a spousal support waiver if enforcing it would result in unconscionable circumstances. 

Ontario courts have described unconscionability as circumstances that are "shocking to the conscience" or inconsistent with the standards of a caring society. 

Factors commonly considered include: 

• Whether the parties were represented by competent counsel; 

• Whether there was any undue influence; 

• The good faith expectations of the parties;  

• Any financial hardship suffered; 

• The parties' health and employability; and

• Their ability to maintain a reasonable standard of living. 

Section 56(4): Setting Aside the Agreement Itself 

A spouse may also seek to invalidate all or part of a domestic contract under section 56(4) of the Family Law Act. 

Common grounds include: 

• Failure to disclose significant assets, debts, or liabilities; 

• A lack of understanding of the nature or consequences of the agreement; or 

• Other contract-law concerns, such as misrepresentation, duress, or unconscionability. 

A successful challenge under section 56(4) can result in the entire agreement or specific provisions, such as a spousal support waiver, being set aside.

Recent Cases Show When Waivers May Be Overturned 

Recent Ontario decisions illustrate the circumstances that can place a spousal support waiver at risk. 

In Brusco v. Brusco et al., 2026 ONSC 3300, the court set aside a marriage contract signed shortly before the wedding where there was no independent legal advice, incomplete financial disclosure, and evidence that the applicant did not fully understand the consequences of the agreement. 

Similarly, in Cantillo v. Inserra Estate, 2025 ONSC 6889, a marriage contract was overturned where the evidence established a significant power imbalance between the parties. The wife was financially dependent on the husband, did not speak English, and did not fully understand the agreement she signed. 

In Bustin v. Vandenberg, 2025 ONSC 1219, the court ordered temporary spousal support notwithstanding a waiver. The court emphasized the substantial income disparity between the parties, the absence of meaningful financial disclosure, and the financial hardship experienced by the applicant. 

By contrast, waivers continue to be enforced where the evidence does not support judicial intervention. In Miglin itself, the Supreme Court upheld the waiver because the agreement was negotiated over a lengthy period with professional assistance and continued to reflect the parties’ intentions. Likewise, in McIntyre v. LaBoissonniere, 2017 ONSC 6682, the waiver was upheld where the applicant failed to provide sufficient evidence demonstrating a significant change in circumstances. 

Key Takeaways 

A spousal support waiver is an important contractual provision, but it is not necessarily immune from future challenges. 

Courts are more likely to intervene where there is evidence of: 

• Inadequate financial disclosure; 

• A significant power imbalance; 

• Lack of independent legal advice; 

• Misrepresentation or misunderstanding of the agreement; 

• Serious financial hardship; or 

• Circumstances that fundamentally depart from what the parties contemplated when the agreement was signed. 

For individuals negotiating a separation agreement or marriage contract, proper financial disclosure and independent legal advice remain the best protections against future litigation. For those considering a challenge to an existing waiver, the specific facts surrounding both the negotiation process and the parties' current circumstances will be critical.

If you have questions about a spousal support waiver or whether an existing agreement may be enforceable, obtaining legal advice early can help clarify your rights and options. Reach out to a member of our team today.