If someone has wronged you, there is a window of time within which you can sue. Miss that window and your claim is gone, regardless of how strong it might have been on the merits. This is what limitation periods are about, and understanding them is one of the most practically important things anyone involved in a legal dispute can do.
This article explains how limitation periods work in Ontario, when the clock starts running, when it can be paused, how specific types of claims are treated, and what the law looks like across the country.
What Is a Limitation Period?
A limitation period is a deadline imposed by law on the right to sue. Once the period expires, a court will generally refuse to hear your claim, no matter how legitimate it is and no matter how serious the wrong done to you. The right to a remedy is extinguished by the passage of time alone.
The law imposes these deadlines for several reasons. Evidence deteriorates over time: memories fade, witnesses die or move away, and documents are lost. Courts are not well-positioned to adjudicate disputes that are years or decades stale. Defendants also have a legitimate interest in finality. At some point, a person who has done something that might be actionable is entitled to move on with their life without the indefinite threat of litigation hanging over them. As the courts have put it, statutes of limitation are acts of “peace” and “repose.”
None of this means the law ignores the legitimate interests of plaintiffs. As this article explains, the rules have been designed to ensure that limitation periods do not begin to run before a person could reasonably have known they had a claim to bring.
Ontario’s Two-Tier System: The Basic and Ultimate Limitation Periods
Ontario’s Limitations Act, 2002, which came into force on 1 January 2004, replaced an older patchwork of rules with a cleaner, two-tier framework.
The Basic Limitation Period: Two Years
The basic limitation period in Ontario is two years. Section 4 of the Limitations Act, 2002 provides that a proceeding shall not be commenced in respect of a claim after the second anniversary of the day on which the claim was discovered.
Two years sounds simple enough, but the calculation depends entirely on when the claim was “discovered.” That word is doing a lot of work, and is explained below.
The Ultimate Limitation Period: Fifteen Years
The ultimate limitation period is the outer limit beyond which no claim can be brought, regardless of when it was discovered. In Ontario, that period is fifteen years from the date of the act or omission on which the claim is based.
The ultimate limitation period functions as a hard stop. Even if you did not discover your claim until year fourteen, and even if the two-year clock from discovery had not yet expired, the ultimate fifteen-year period forecloses the claim once it runs out. The ultimate period exists because the law cannot permit potential defendants to remain exposed to lawsuits indefinitely.
The fifteen-year period runs from the date of the act or omission, not from the date of discovery. This means it runs regardless of whether the injured party knew anything had happened.
When Does the Clock Start? The Discoverability Principle
The most important concept in Ontario limitations law is discoverability. The two-year clock does not start from the date the wrong was committed. It starts from the date the claim was discovered, or ought to have been discovered with reasonable diligence.
Under section 5 of the Limitations Act, 2002, a claim is discovered on the earliest date that a person knew, or ought reasonably to have known, all of the following:
that they suffered an injury, loss, or damage; that the injury, loss, or damage was caused by an act or omission; that the act or omission was that of the defendant; and that, having regard to the nature of the injury, a legal proceeding would be an appropriate means to remedy it.
All four of these conditions must be met before the clock starts. The required degree of knowledge is more than a suspicion, but less than certainty. The Supreme Court of Canada confirmed this standard in Grant Thornton LLP v. New Brunswick: perfect knowledge is not required, and knowledge of the precise cause or full extent of the loss is not necessary. Knowledge of damage (that your situation has gotten worse) is required; you do not need to know the precise monetary extent of your loss.
A person is presumed to have discovered their claim on the date the act or omission occurred unless they can show that one or more of those four conditions was not met until later. This presumption puts the burden on the claimant to explain why discovery happened later than the wrong itself.
Ignorance of the law is not a basis for delaying discovery. A citizen is presumed to know the law of the land. But ignorance of the relevant facts, particularly where the facts were hidden from the claimant, is a different matter entirely.
Importantly, sitting on your hands will not extend the limitation period. As the Ontario Court of Appeal warned in Longo v. MacLaren Art Centre, a limitation period will not be tolled while a plaintiff takes no steps to investigate their claim.
When Is the Clock Paused? Suspension of Limitation Periods
The law recognizes that certain circumstances make it genuinely impossible or unfair for a person to bring a claim. In those situations, the running of limitation periods is suspended until the obstacle is removed.
Minors
A person under eighteen cannot generally sue on their own. If a claim arises while the claimant is a minor and they are not represented by a litigation guardian, the basic two-year period does not run until they turn eighteen. The ultimate fifteen-year period is also suspended while the claimant is a minor, but only if the claim arose while they were a minor. If you were an adult when your claim arose, you cannot rely on this suspension simply because the events underlying the claim happened when you were young.
Incapable Persons
If a person is incapable of commencing a proceeding because of a physical, mental, or psychological condition, and is not represented by a litigation guardian, the basic two-year period does not run during that period of incapacity. The ultimate limitation period is also suspended in these circumstances.
Once the incapacity ends, the clock resumes. The remaining ultimate limitation period is the longer of whatever time was left when the disability began, or one year from the date the disability ceases.
Fraudulent Concealment
Where the defendant wilfully conceals essential facts from the person with the claim, the running of the limitation period is suspended for the duration of the concealment. A defendant cannot benefit from a limitation defence that was only available because of their own deception. Ontario’s Limitations Act, 2002 addresses this through the discoverability framework: if a plaintiff could not have discovered the claim because the defendant was hiding it, the clock does not start until the concealment ends.
Sexual Assault
Sexual assault claims receive special treatment. There is no limitation period in Ontario for a civil claim arising from sexual assault. The Supreme Court of Canada recognized in M.(K.) v. M.(H.) that victims of sexual assault may be unable to bring claims for many years due to the psychological impact of the abuse, the relationship dynamics that often accompany it, and the difficulty of understanding that the conduct was actionable. Assault claims arising in intimate or dependent relationships are treated similarly.
Acknowledged Debts and Part-Payments
Where a defendant acknowledges a debt or makes a part-payment, this can reset or extend the limitation period. The acknowledgment must be in writing and signed by the debtor or their agent. This is particularly relevant in contract and lending disputes.
Common Types of Claims: Specific Deadlines
While the general two-year period applies broadly, certain types of claims carry specific rules worth knowing.
Breach of Contract
Contract claims are subject to the standard two-year limitation period running from discovery. In Ontario, the clock starts when you discover that you suffered injury, loss, or damage as a result of the breach, not simply when the breach itself occurred. For many straightforward breaches, those two dates will be the same. But where the harm only becomes apparent later, the discoverability principle can shift the starting point.
Personal Injury and Motor Vehicle Accidents
Personal injury claims, including those arising from motor vehicle accidents, are governed by the two-year basic limitation period from discovery. In Ontario, there are additional Insurance Act provisions that impose shorter notice and claim periods in some circumstances, and these interact with the general limitation framework in ways that are not always obvious. Motor vehicle accident victims in particular should get advice early, as Insurance Act deadlines can expire before the general two-year period does.
Professional Negligence
Claims against lawyers, doctors, accountants, engineers, and other professionals are subject to the two-year basic period from discovery. Because professional negligence claims often involve damage that is not immediately apparent, the discoverability principle plays an important role. The harm from bad legal advice may only manifest when a case is lost. The harm from a medical error may only be discovered years after the procedure. In each case, the limitation period runs from the point at which the client knew or ought to have known the essential facts outlined above.
Defamation
Defamation claims in Ontario are subject to the standard two-year limitation period under the Limitations Act, 2002, with the clock running from discovery. However, there are important additional requirements layered on top of this. Under the Libel and Slander Act, actions against newspaper publishers and broadcasters require that written notice of the claim be given within six weeks of the defamatory publication coming to the plaintiff’s attention, and the action must be commenced within three months of that notice. These are strict requirements that operate separately from, and in addition to, the general limitation period.
If defamatory words are repeated, a fresh cause of action arises with each new publication. This can be particularly significant in the context of online defamation, where content may be re-published or shared by different parties at different times.
Real Property Claims
Claims involving real property are governed by the Real Property Limitations Act rather than the Limitations Act, 2002. Adverse possession claims, for example, require ten years of open, continuous, and adverse possession before a claim can be made. This is a separate and distinct regime from the general limitations framework.
Claims Against the Crown and Public Authorities
Suing a government body is not the same as suing a private party. Many statutes imposing liability on the Crown or on municipalities require advance notice of a claim within a specified period, often much shorter than the general two-year period. For example, claims arising from road maintenance in Ontario require written notice to the municipality within ten days of the occurrence. Failure to provide this notice can be fatal to the claim even if the general two-year period has not expired.
Ontario Limitation Periods at a Glance
The chart below summarizes the limitation period for the most common types of civil claims in Ontario and explains when the clock starts running for each.
| Type of Claim | Limitation Period | When the Clock Starts |
|---|---|---|
| General civil claims (contract, negligence, fraud, etc.) | 2 years (basic) 15 years (ultimate) | When you knew or ought to have known that you suffered a loss caused by the defendant’s act or omission, and that suing is an appropriate remedy |
| Defamation (general) | 2 years | When the defamatory publication came to your attention and you knew it caused you harm. Each new publication creates a fresh cause of action. |
| Defamation against a newspaper or broadcaster | 3 months to commence action; written notice required within 6 weeks of publication | Notice must be given within 6 weeks of the publication coming to your attention. Failure to give notice on time bars the claim entirely. |
| Personal injury | 2 years | When you knew or ought to have known you were injured and that the injury was caused by the defendant’s conduct |
| Motor vehicle accident | 2 years (subject to Insurance Act notice requirements) | Generally from the date of the accident, or later if injuries were not immediately discoverable. Insurance Act deadlines may be shorter; get advice promptly. |
| Professional negligence (lawyers, doctors, accountants, etc.) | 2 years | When you knew or ought to have known that the professional’s error caused you a loss, often later than the date of the negligent act itself |
| Sexual assault | No limitation period | There is no deadline. A civil claim for sexual assault can be brought at any time. |
| Assault in an intimate or dependent relationship | No limitation period | There is no deadline where the assault occurred in an intimate or dependent relationship. |
| Real property / adverse possession | 10 years (under the Real Property Limitations Act) | From the date the right to recover the land first accrued (typically when adverse possession began) |
| Claims against a municipality (e.g. slip and fall on municipal property; road maintenance) | 2 years, but written notice required within 10 days of the event | Notice must be given to the municipality within 10 days of the injury. Failing to give notice on time can extinguish the claim regardless of the 2-year period. |
| Claimant is a minor | 2-year clock does not run while under 18 (if claim arose during minority) | Clock starts on the claimant’s 18th birthday (or earlier if a litigation guardian is appointed). The 15-year ultimate period is also suspended. |
| Claimant is incapable | 2-year clock does not run during incapacity | Clock starts when the incapacity ends (or when a litigation guardian is appointed). The 15-year ultimate period is also suspended. |
This table is a general summary for reference only. Special statutes, insurance policy terms, and the specific facts of your situation can alter these periods. Always obtain legal advice for your specific circumstances.
What Happens If You Miss the Deadline?
In most cases, a defendant who has the benefit of an expired limitation period is in a very strong position. The expiry of the limitation period is a complete defence. The court does not consider the merits of the underlying claim. It does not matter whether the defendant clearly wronged you, or whether your damages were significant. If the limitation period has expired and is properly raised as a defence, the claim fails.
This is why the limitation period must be pleaded. It is an affirmative defence that the defendant must specifically raise in their statement of defence. A court will not raise it on the defendant’s behalf. If a defendant forgets to plead it, they may lose the right to rely on it.
From the plaintiff’s perspective, the best practice is always to commence a proceeding before the limitation period expires, even if negotiations are ongoing or the parties believe they are close to a settlement. Commencing a proceeding preserves your rights. You can always discontinue or settle after commencing; you cannot revive a claim that has been extinguished by time.
If you think your limitation period may have passed, do not assume all is lost without getting legal advice. The discoverability analysis is fact-specific and often contested. In appropriate cases, the question of when a claim was discovered is a genuine issue that a court must determine on the evidence.
Limitation periods are unforgiving, and the discoverability analysis can be complicated. If you are involved in a dispute and are uncertain whether your limitation period has expired, or is about to, our civil litigation and commercial litigation teams can assess your situation. For claims involving defamation, the additional notice requirements under the Libel and Slander Act make prompt action especially critical. Contact Grigoras Law to discuss your matter.
Conclusion
Limitation periods can seem like a technicality. They are not. They are a fundamental feature of the civil justice system, designed to balance the legitimate interests of claimants in having their day in court against the equally legitimate interests of defendants in knowing that, at some point, they are safe from being sued for old wrongs.
In Ontario, the framework is broadly fair. The two-year basic period runs from discovery, not from the wrong itself. The fifteen-year ultimate period provides a meaningful outer boundary. Special rules protect those who could not have brought claims earlier, including minors, incapable persons, and victims of sexual assault.
But fairness does not mean flexibility. The deadlines are real, and courts enforce them. If you have a potential claim, understanding the applicable limitation period and acting before it expires is not optional. It is the first and most important step in protecting your rights.
