What Is Zombie Debt?
Zombie debt is old debt, often past its statute of limitations or previously written off, that resurfaces when a new collector attempts to collect on it, sometimes years after you last heard about it.

Why It Resurfaces
Old, uncollected debts are frequently sold, sometimes repeatedly, to new debt buyers, who may attempt to collect even if the debt is old, inaccurate, or past the point where it can be legally sued over.
For example, a $600 credit card balance from six years ago might get sold from the original bank to one debt buyer, then resold to another a year later, each time for pennies on the dollar. You could suddenly get a call about it even though you haven't heard anything in years, and the company calling may not even be the one you originally owed.
The Biggest Risk: Restarting the Clock
In many states, making even a small payment, or in some cases just acknowledging the debt is yours, can restart the statute of limitations clock, making an otherwise time-barred debt suddenly suable again. Always check your state's rules before you pay or promise anything.
How to Handle It
Verify the debt before paying anything, request written validation
Check your state's statute of limitations status before acknowledging or paying
Don't make a payment or promise until you've confirmed both the amount and the SOL status