Verification that this debt was assigned or sold to collector. Complete accounting of alleged debt.1. In the sample letter, fill in your personal information. Illinois Free Debt Validation Letter. Use our debt validation letter to request the validity of a debt. List four trade references with complete address, fax number or email address. How to use this sample letter: 1. Read the background below. 2. This letter is in reference to the account number identified above and its outstanding debt. Use this sample letter to dispute mistakes on your credit report.