A genuinely important distinction courts have made explicit
Under Idaho Code § 5-219(4), Idaho courts have specifically held that this statute does not adopt a discovery rule for professional-malpractice claims. Instead, the two-year limitations period begins when some damage is objectively ascertainable — a standard that's genuinely different from, and sometimes earlier than, the date the injured person actually realizes or discovers they've been harmed.
Why the difference actually matters
Under a true discovery rule, the clock typically starts when a reasonable person in the claimant's position would have become aware of the injury. Idaho's "objectively ascertainable" standard instead asks whether some damage existed in a way that could, in principle, have been identified — a distinction that can start the clock earlier than when the injured person subjectively discovered anything was wrong. This has real consequences: someone who didn't personally realize they'd been harmed until well after damage first became objectively identifiable could find their claim time-barred sooner than a true discovery rule would allow.
A narrow discovery rule does still exist for products liability
Separately, Idaho courts have described § 5-219(4) as containing a "very narrow discovery rule" specifically for products liability claims — distinct from the ascertainable-damage standard used for professional malpractice. The precise scope of this narrow rule is worth confirming with an attorney for any products liability claim where timing is close.
Minors: the clock waits for 18
For minors, the statute of limitations generally does not begin running until the minor turns 18, and the full two-year period then runs from that birthday — giving a child injured well before adulthood until roughly their 20th birthday to bring a claim.
Mental incompetence and absent defendants
Idaho also tolls the statute of limitations for the period someone was mentally incompetent at the time of the injury, under Idaho Code § 5-230. Separately, under Idaho Code § 5-229, the clock is tolled for the period a defendant is out of state and cannot be located for service of process — though this generally doesn't apply to a foreign corporation that remains subject to Idaho jurisdiction and can be reasonably served outside the state.