A debt so old that the statute of limitations bars a lawsuit to collect it - what a collector may and may not do about it, how a payment can revive it, and why the credit-reporting clock is a different clock.
A debt does not disappear when its statute of limitations runs, but the creditor's ability to sue on it does. The limitation period for a contract or account claim is set by state law, runs from a date the state's rule defines - usually the last payment or the default - and varies between states and between kinds of debt. Once it has passed the debt is time-barred: the creditor or a debt buyer may still ask to be paid, but a lawsuit can be defeated by raising the limitation period as a defence. It is a defence, not an automatic bar: a consumer who ignores the summons and lets a default judgment enter has usually lost the point.
Federal regulation now prohibits a debt collector from suing or threatening to sue on a debt it knows or should know is time-barred, and a collector that does so violates the Fair Debt Collection Practices Act whether or not the consumer knew the debt was old. The Supreme Court has held, however, that filing a proof of claim for a time-barred debt in a consumer's bankruptcy is not a violation, because the bankruptcy process is designed to sort such claims out.
The trap is revival. In many states a partial payment, a written acknowledgment of the debt, or a new promise to pay restarts the limitation period, so a small "good faith" payment on a debt that was time-barred can make it collectible in full. Separately, the period during which a debt may appear on a credit report is set by federal law and runs independently of the state limitation period; a debt can be time-barred but still reportable, and reportable long after it could be sued on.
Anyone contacted about an old debt should find out, before paying or promising anything, whether it is time-barred in their state and whether a payment would revive it - a legal aid office or a consumer lawyer can answer that from the dates. Anyone sued on an old debt should answer the lawsuit and raise the limitation defence, since it is lost by default; and a consumer who was threatened with suit on a barred debt may have a claim of their own under the federal statute.
Choose your state. Each link opens the directory page for the city in that state with the most currently published law firms in this practice area; a +n beside the city is how many other cities in the state also have one. The list is generated when this page loads, so a state whose listings have lapsed drops out rather than becoming a dead link.