When the statute starts to run in legal malpractice is an important consideration.  Here is a Pennsylvania case.  It’s a complex anaysis, taking into account the date of the mistake, the date that actual damage happens, and continuing representation [not mentioned in this case]. 

"In Wachovia v. Ferretti, the appeals court panel rejected Wachovia’s argument that it could not have brought a negligence claim against its attorney for an act that didn’t result in damages until years later.

The court instead ruled that the statute of limitations for a breach of contract claim starts when the duty is breached and is only tolled until the plaintiff should reasonably have found out about the claim — not until a judgment is entered or appeals are finished.

The appeals court pointed out that its ruling could require a client to pursue two legal actions with competing interests at the same time.

"We recognize Wachovia’s public policy arguments, including their argument that, if the statute of limitations is to accrue upon the breach of a duty, a plaintiff in a legal malpractice action would be forced to take competing positions while defending the underlying claim and prosecuting their own legal malpractice action premised on that underlying claim," Judge John T. Bender said for the panel.

"Although we recognize this potential dilemma, the overriding public policy concern is that not commencing legal malpractice actions in a timely fashion results in stale claims."
"In Wachovia v. Ferretti, the appeals court panel rejected Wachovia’s argument that it could not have brought a negligence claim against its attorney for an act that didn’t result in damages until years later.

The court instead ruled that the statute of limitations for a breach of contract claim starts when the duty is breached and is only tolled until the plaintiff should reasonably have found out about the claim — not until a judgment is entered or appeals are finished.

The appeals court pointed out that its ruling could require a client to pursue two legal actions with competing interests at the same time.

"We recognize Wachovia’s public policy arguments, including their argument that, if the statute of limitations is to accrue upon the breach of a duty, a plaintiff in a legal malpractice action would be forced to take competing positions while defending the underlying claim and prosecuting their own legal malpractice action premised on that underlying claim," Judge John T. Bender said for the panel.

"Although we recognize this potential dilemma, the overriding public policy concern is that not commencing legal malpractice actions in a timely fashion results in stale claims."