I recently got two letters in the mail claiming that I was held overpaid benefits for two separate amounts. It says I need to file only one.Read your letter carefully, and follow the instructions outlined in your letter to respond. View refund and overpayment credit information. System IRMS User Guide for Localities. An employee's overpayment debt may be waived in whole or in part. This chapter provides a summary of the overpayment process in general terms and the instructions fundamental to implementing the provisions of 5 USC § 8129 Employees can request a waiver of salary overpayment debt up to three years after a debt is discovered;