Your letter must include your name, address, Social Security number, and why you disagree with the determination. Customer: sat 9217 I received a potential overpayment letter from California edd for several weeks in the months of march to june of 2016.Your overpayment notice explains why you have been overpaid, your overpayment amount, your repayment options, and your appeal and waiver rights. If HMRC have overpaid from previous years then in order to avoid complications you should write to them and confirm the amount you owe.