Zombie debt is old debt that is no longer legally collectible. However, debt collectors might still try to collect it, somewhat reviving it. It is potentially illegal to collect debt passed the statute of limitations. Debt collectors will use aggressive and intimidating methods to try and collect zombie debt, posing a risk to one's financial standing. There is protection offered by the Fair Debt Collection Practices Act (FDCPA) that limits the behaviors and actions of the debt collectors. Try not to spend too much time on the phone with them; instead, gather their address and mail a certified letter to dispute the debt. The biggest potential consequences of interacting with zombie debt are restarting the statute of limitations.