Ontario Limitations Act: Deadlines, Exceptions, and Tolling

Under the Ontario Limitations Act, you generally have two years from the day you discovered a claim to start a lawsuit, with a hard outer cap of 15 years from the event itself. Those two numbers govern most civil disputes in the province, from breach of contract to personal injury to property damage. The exceptions are narrow but important, and a few of them remove the deadline entirely.

The Two-Year Basic Deadline

Section 4 sets the default: no court proceeding can be started more than two years after the day the claim was discovered.¹ Negligence, breach of contract, property damage, and the broad run of civil actions all fall under this window. Miss it, and the defendant can move to dismiss. Judges have very little discretion to extend the deadline unless a specific statutory exception applies.

The cost of a late filing goes beyond losing the case. Legal fees already spent are not recoverable, and money put into expert reports or document production is gone. Treating the two-year date as a hard deadline rather than a rough target is the safer approach.

When the Clock Actually Starts

The two years do not always run from the date of the incident. Section 5 ties the start to the day you discovered, or reasonably should have discovered, four things: that you suffered an injury, loss, or damage; that it resulted from someone’s act or failure to act; that the person responsible is the one you would sue; and that a lawsuit would be an appropriate way to address it.¹ All four must be in place before the clock starts.

The Act also applies an objective check. Section 5(1)(b) asks when a reasonable person in your situation should have known those things. Ignoring warning signs or sitting on information without investigating can push the discovery date earlier than when you actually figured it out.

Section 5(2) adds a presumption that you knew about the claim on the day the act or omission happened. You can rebut it, but the burden is yours. In practice, a plaintiff relying on delayed discovery needs evidence: medical records showing a latent condition, inspection reports, forensic analyses, or similar documentation that the harm was not apparent at the time.

The Supreme Court of Canada set the threshold in Grant Thornton LLP v. New Brunswick (2021). A limitation period starts when the plaintiff has actual or constructive knowledge of the material facts supporting a plausible inference that the defendant is liable. You do not need to know the full extent of the damage or hold a complete legal theory. Enough facts to make a reasonable case is the trigger.

The 15-Year Outer Cap

Even with a legitimate reason for late discovery, Section 15 draws a hard line: no proceeding can be started more than 15 years after the act or omission that caused the harm.¹ This ultimate limitation period runs from the event itself, not from discovery. A loss discovered in year 16 is out of time no matter how diligent you were.

There is one narrow exception. The 15-year clock does not run during any period when the defendant deliberately misled you about whether a lawsuit would be an appropriate remedy. Active concealment or deception that steered you away from suing does not count against you. Outside that carve-out, and outside the no-limit categories below, the 15-year cap is absolute.

Claims With No Deadline at All

Some proceedings have no limitation period. Sections 16 and 17 list them.

Sexual Assault and Abuse

Any proceeding based on sexual assault can be brought at any time, no matter when it occurred or when a previous limitation period might have expired.¹ The exemption also covers other sexual misconduct when the victim was a minor at the time, the perpetrator held a position of trust or authority, or the victim was dependent on them. Non-sexual assault is covered on the same basis when the victim was a minor, was in an intimate relationship with the assailant, or was financially, emotionally, or otherwise dependent on them. These exemptions are retroactive, and they reach related claims arising from the same conduct, including negligence, breach of fiduciary duty, and vicarious liability.

Section 16 Categories

Section 16 also removes the limitation period from several other proceedings:¹

Enforcing a court order or judgment.
Family support proceedings under the Family Law Act, and enforcement of support agreements that could be filed under that Act.
Crown recovery of fines, taxes, penalties, or interest.
Recovery of money owed on student loans, medical resident loans, or grants under the applicable federal and provincial legislation.
Proceedings seeking only a declaration of rights, with no other remedy attached.
Proceedings by a debtor to redeem collateral or by a creditor to realize on it.

Undiscovered Environmental Claims

Section 17 handles environmental harm separately. If an environmental claim has not been discovered, no limitation period applies.¹ Once the claim is discovered, the normal two-year and 15-year periods take over. Soil and groundwater contamination that sits undetected for years can still support a lawsuit when it finally surfaces.

What Pauses or Restarts the Clock

Minors and Incapable Persons

Section 6 suspends the two-year period while a claimant is both a minor and without a litigation guardian.¹ Once the child turns 18 or a litigation guardian is appointed, the clock starts or resumes. Section 7 does the same for adults who are incapable of starting a proceeding because of a physical, mental, or psychological condition, as long as they are also unrepresented by a litigation guardian. Capacity is presumed, so anyone relying on this suspension needs evidence that the person was genuinely unable to act. If the suspension ends with fewer than six months left on the limitation period, the Act gives the claimant a full six months from that point. Once a litigation guardian is in place, the Section 5 discovery rules apply to the guardian as if the guardian were the person with the claim.

Acknowledgment of a Debt

Section 13 can reset the two-year window entirely. If someone acknowledges liability for a claim involving payment of a specific sum of money, recovery of personal property, or enforcement of a charge on personal property, the limitation period restarts from the date of the acknowledgment.¹ A partial payment or an email admitting an outstanding balance can give a creditor a fresh two years from that date. Debtors nearing the end of a limitation period should be careful about any written communication that confirms the debt.

Agreements That Change the Deadlines

Section 22 lets parties alter limitation periods by contract, but the rules depend on when the agreement was made and who signed it.¹ Agreements made before January 1, 2004 can vary or exclude limitation periods outright. For agreements made on or after October 19, 2006, the rules split by party type.

Non-business agreements, meaning any contract where at least one party is a consumer, can only suspend or extend a limitation period. They cannot shorten or eliminate it. Business agreements, where no party qualifies as a consumer under the Consumer Protection Act, 2002, carry more flexibility. Businesses can agree to shorten, extend, suspend, or exclude the basic two-year period. The 15-year ultimate limitation period can only be suspended or extended, never shortened or removed, and only if the claim has already been discovered.

If you are a consumer signing a contract with a shortened limitation clause, that clause is likely unenforceable. If you are a business negotiating a commercial deal, you have real room to tailor deadlines, but the 15-year cap remains close to immovable.

When Another Statute Sets the Deadline

The Limitations Act is not the only source of filing deadlines. Section 19 gives priority to limitation periods set out in other Ontario statutes that are listed in the Act’s Schedule.¹ If a statute is not on the Schedule, any limitation period it tries to create has no effect.

Several significant statutes sit on that Schedule, including the Construction Act, the Insurance Act, the Securities Act, the Libel and Slander Act, and the Trustee Act. Construction lien claims and libel and slander claims, for example, carry windows considerably shorter than two years. Checking whether a specialized statute governs your situation is one of the first steps in evaluating a potential claim.

A Note on Pre-2004 Claims

The Limitations Act came into force on January 1, 2004 and replaced the older patchwork of limitation statutes. Section 24 governs older claims.¹ If the former limitation period had already expired before January 1, 2004, the claim is gone. If it had not expired and the claim was undiscovered, the new Act applies as if the act or omission occurred on January 1, 2004. If the claim was already discovered before 2004, the former limitation period continues to apply. Sexual assault and abuse claims are retroactively exempt regardless. These transition questions rarely come up today, but they can still matter for historic institutional abuse cases or long-latent property damage.

1
Ontario.ca. Limitations Act, 2002, SO 2002, c 24, Sched B