February 29, 2020
[City, State, Zip]
Dear [Recipient's name],
Our records indicate that you have an outstanding balance of [$Amount] with a due date of [xx/xx/xxxx]. We have yet to receive this payment. Please find a copy of the invoice enclosed.
If this amount has already been paid and sent, please disregard this notice and we apologize for any inconvenience. Otherwise, please forward us the amount stated above that is past due by [xx/xx/xxxx]. As our written agreement states, we will start charging a 5% interest charge for any outstanding balance greater than 30 days.
Thank you for your cooperation regarding this matter. We sincerely hope we can continue doing business together in the future.
[Your Name, Title]