We obtained dismissal of an accounting malpractice claim on preliminary objections in the Philadelphia Court of Common Pleas. The plaintiffs alleged that their accountant improperly prepared their tax returns—as married filing jointly—and failed to claim business losses, that resulted in an unexpected tax liability being owed. Although the plaintiffs attempted to rely on the discovery rule to toll the statute of limitations, the defense successfully argued that the plaintiffs were on notice of the alleged negligence by the time they received the prepared tax returns, and that their failure to investigate potential claims at that time was a failure to exercise due diligence as a matter of law. We further argued that because they were under a duty to investigate earlier, the plaintiffs could not successfully allege that they could not have known of their claims until they hired a tax attorney to investigate. Because the plaintiffs did not bring their negligence claim until more than two years after they received their prepared tax returns, their claims were barred by the Statute of Limitations.