A Verification Letter (often called a Debt Validation Letter) is a written request sent to a collection agency asking them to prove a debt is accurate and legally collectible. Under the Fair Debt Collection Practices Act (FDCPA), you have the right to request verification within 30 days of being contacted by a debt collector.
The collector must provide details such as the original creditor, the amount owed, and documentation showing you are responsible for the debt. If they cannot properly verify it, they must cease collection efforts and may be required to remove the account from your credit report.