As the payment is now overdue, we kindly request your immediate attention to settle the outstanding balance. Follow these 10 tips to write overdue payment letters for requesting outstanding payments from your late paying customers.What should be included in a demand 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. Your debt settlement proposal letter must be formal and clearly state your intentions and what you expect from your creditors. Recovering overdue funds from customers is frustrating. These overdue invoice letter templates show you the right tone and language to use. State the exact amount the client owes, including any interest or late fees, to avoid any confusion. A rent payment can only be considered late if it is received more than five days after it is due.