Enforcing a separation agreement in Ontario
Last updated: June 16, 2026
A properly signed Ontario separation agreement is binding. If the other side stops complying, you can enforce it. How depends on the type of term: support terms can be enforced through the Family Responsibility Office the same way a court order is; other terms (property, the matrimonial home, lump-sum payments) are enforced through a court application. A properly drafted agreement — with full financial disclosure, Independent Legal Advice, witnessed signatures, and filed with the court where appropriate — is far easier to enforce than a casually-signed one. The first lesson of enforcement is: do the work at signing time.
Section 35 of the Family Law Act allows a separation agreement to be filed with the court so the support terms can be enforced as if they were a court order. The Ontario Courts of Justice Act governs enforcement of non-support terms.
When this does apply
Enforcement applies the moment the other side stops complying with a clear, enforceable term of the agreement. Common examples: missed support payments, refusal to sign documents required for the transfer of the matrimonial home, failure to pay an equalization payment by the agreed deadline, withholding a child contrary to the agreed parenting schedule. The agreement has to be in writing, signed by both spouses, and (for the easiest path) filed with the court. Oral side-agreements and undocumented promises are not enforceable. Each enforcement path runs on different rules: support through the FRO is administrative and largely automatic; property enforcement through court is an application with affidavit evidence.
When this doesn't apply
Enforcement does not work for terms that were never put in writing, or for promises that were not part of the signed agreement. It also does not work where the agreement itself is being challenged — if the other spouse is trying to set the agreement aside under section 56(4) of the Family Law Act, the enforcement application may be paused while that challenge plays out. Finally, enforcement is not the same as variation: if you want to change a term (because circumstances have shifted), see how to change a separation agreement. Enforcement applies the agreement as written.
What to do
Step 1 — Document the breach. Write down exactly what the agreement requires, what the other side has done (or not done), and when. Include copies of emails, texts, missed payment records — anything that shows the breach.
Step 2 — Try written notice first. Send a clear, written demand to the other side (or their lawyer) stating the breach and a reasonable deadline to remedy. Many breaches resolve here. Keep a copy of the demand and the response (or non-response).
Step 3 — For support breaches: file with the FRO if not already filed. Once filed with the court under section 35 of the Family Law Act, the FRO can collect and enforce the support terms with the same tools it uses for court orders — payroll deduction, licence suspension, garnishment.
Step 4 — For non-support breaches: apply to court. File a Notice of Application or a Motion to Enforce at the Superior Court of Justice. Set out the agreement, the breach, the relief requested. The court can order specific performance (compelling the other side to comply), monetary damages, or both.
Step 5 — If the other side challenges the agreement, prepare to defend it. Agreements signed with disclosure and ILA hold up far more often than agreements signed without. Pull out the ILA certificates, the disclosure records, and any draft history showing both sides negotiated.
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Frequently asked questions
Can you enforce a separation agreement in Ontario?
Yes - a properly signed Ontario separation agreement is binding and enforceable. Support terms can be enforced through the Family Responsibility Office once the agreement is filed with the court under section 35 of the Family Law Act. Other terms (property, lump-sum payments, the matrimonial home) are enforced through a court application at the Superior Court of Justice.
How do I enforce support in an Ontario separation agreement?
File the agreement with the court under section 35 of the Family Law Act if not already filed. Once filed, the agreement is treated like a court order for support enforcement purposes. Register it with the Family Responsibility Office. The FRO can then collect and enforce the support terms using its full toolkit - payroll deduction, drivers licence suspension, bank garnishment, federal tax-refund interception.
What if my ex breaches the non-support parts of our Ontario separation agreement?
File a court application or Motion to Enforce at the Superior Court of Justice. Set out the agreement, the breach, and the relief you want (compelling compliance, monetary damages, or both). The court has the same power to enforce a separation agreement as it does to enforce any other contract. Document the breach in writing before filing.
Can my ex set aside the separation agreement when I try to enforce it?
They can try - under section 56(4) of the Family Law Act, agreements can be set aside on three narrow grounds (failure to disclose, lack of understanding, gross unfairness). Agreements signed with full disclosure and Independent Legal Advice are very hard to set aside. The set-aside application may pause your enforcement until resolved, but a well-drafted agreement usually wins.
What is section 35 of the Family Law Act in Ontario?
Section 35 of the Ontario Family Law Act allows a separation agreement (and certain other domestic contracts) to be filed with the court. Once filed, the support provisions are treated as if they were court orders for enforcement purposes - including registration with the Family Responsibility Office. Filing is a one-time administrative step and the most important enforcement-readiness move you can make.