If you are contacted by a collection agency about an outstanding debt, respond immediately if you don't agree that you owe money. Dispute the debt in writing by sending a letter to the collection agency by certified mail with a return receipt requested. This will place responsibility on the collection agency to verify the debt and supply you with proof that you owe the money. The collection agency cannot attempt to collect the debt while its validity is being checked out with the original creditor.

Although the law gives you 30 days from the first contact to dispute the debt in writing, you should respond right away because the collection agency can continue to try to collect the money until you dispute the debt in writing, and if you miss the deadline for disputes, the collection agency will assume that you are responsible for the debt.