This program will help you write a letter that formally requests the money you are owed. This is called a Demand Letter.What do you include in a debt collection letter? We've created ready-to-use collection letter templates. Read on below to find out what every letter should say in order to collect payment as soon as possible. Provide a comprehensive breakdown of the outstanding balance, including the original invoice amount, service dates, and any additional charges. Money Owed Demand Letter – Strictly for debts or outstanding balances. 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. It has come to our attention that your account is overdue for payment.