How To Write A Formal Demand Letter For Payment And Money Owed To Clear Outstanding Debt? A demand letter is also called a debt collection letter.The Demand Request for Outstanding Fee Form must be completed and notarized prior to submission to LADBS. Use this letter to ask a customer to pay the money that they owe you. Put your business letterhead at the top of the letter. Fill in your information on the template letter and edit it as needed to fit your situation. 3. Print and mail the letter. What do you include in a debt collection letter? First, do not attempt to mislead the debtor as to your status. Contact the Citywide Collection Unit at (213) 978-7900 to request a demand letter.