Every claim has a deadline, and missing it ends the matter regardless of merit. The length of the period is usually easy to find. The difficulty is the start date.
Accrual generally runs from the breach or the injury — but several doctrines move it. The discovery rule, where applicable, starts the clock when the claimant knew or reasonably should have known of the injury and its cause; it applies to some claims and not others, and the “should have known” limb rewards diligence and punishes wilful ignorance. Continuing violations may restart or extend it where the conduct is ongoing rather than a single act. Tolling can suspend it — by agreement, by fraudulent concealment, or by statute.
Different theories arising from the same facts frequently carry different periods: a contract claim, a fraud claim and a statutory claim over one transaction can have three deadlines, and the shortest is often the one that matters most.
Two practical consequences. Assess the deadline at the first meeting, not after investigation — the analysis of when a claim arose is itself work. And where a deadline is near and the facts are incomplete, a written tolling agreement is usually cheaper and better than a hurried complaint.