This brief but important letter notifies a customer that he or she has overpaid you. It can serve as a very good customer relations letter.The salary overpayment resulted because . This model letter as a legally approved form for a client to use when informing an employee about correcting a wage overpayment. How do you write a letter to inform of a double payment? This memorandum serves as notification of an overpayment of wages that you received and the subsequent repayment that is your responsibility. Our Overpayment Notification Letter Template addresses overpayment errors promptly, ensuring clear communication and resolution for all parties involved.