This program will help you write a letter that formally requests the money you are owed. This is called a Demand Letter.Ask for immediate payment of the unpaid amount in the demand letter and include details on how they can pay. Follow these 10 tips to write overdue payment letters for requesting outstanding payments from your late paying customers. Below, we've created an example of a debt settlement proposal letter that you can use as a guide. Your letter can be sent via your preferred contact method. Review the sample letters below. You should use these letters only if you are willing and able to negotiate a settlement. Recovering overdue funds from customers is frustrating. These overdue invoice letter templates show you the right tone and language to use.