Your letter must include your name, address, Social Security number, and why you disagree with the determination. To submit an inquiry electronically to OP, please complete the Overpayments Online Form.Please download the form, complete each field and print. Include the form with your refund so we can properly apply the refund and record the receipt. Blue Shield will request a refund of the overpayment within 365 days of the original payment date. If we have identified an overpayment and request a refund, please mail the check along with a copy of the overpayment request letter we sent you. Many times when a third-party payer mistakenly pays a dental provider, the payer will request a refund of the overpaid amount.