How long do I have to start a lawsuit in Ontario before it is too late?

Ontario's Limitations Act establishes a basic two-year limitation period for most civil claims. This means you generally have two years from the day you discovered (or reasonably ought to have discovered) that you have a claim to start a court proceeding. If you miss this deadline, the defendant can raise the limitation period as a complete defence and your claim will be statute-barred, regardless of how strong it would otherwise have been.

The discovery rule is important: the clock starts when you knew, or should have known, that a loss occurred, that it was caused by the defendant's act or omission, and that a legal proceeding would be an appropriate way to address it. In some situations — for example, where damage was hidden or not apparent — discovery may be delayed.

There is also a 15-year ultimate limitation period, which runs from the date the act or omission occurred regardless of discovery. Once 15 years pass, most claims are extinguished even if you only recently discovered the harm.

Some claims have their own limitation periods set by specific statutes — for example, claims against municipalities, construction liens, and defamation — so the two-year default does not apply to every situation. If you are unsure when your limitation period expires, get advice promptly; acting quickly is always safer.