Dear _________________

Thank you for your check in the amount of ________________ (amount) which was in payment of the discount you had inadvertently taken in paying our invoice.

We are sorry that there was a misunderstanding regarding the period of time allowed in which to take advantage of our discount incentive and appreciate having had the opportunity to clarify our policy with you.

If you have any other questions regarding our credit policy, please contact me and I will be happy to provide you with any information you require. Thank you very much for your recent order.