California Code, Education Code - EDC § 25955

To recover an amount overpaid under this part, the monthly allowance payable under the Defined Benefit Program may be reduced by the amount of the overpayment. If the overpayment is not due to fraud or intentional misrepresentation of facts by the recipient of the allowance or benefit, the monthly allowance may be reduced by no more than 5 percent if the overpayment was due to error by the system, the county superintendent of schools, a school district, or a community college district, and by no more than 15 percent if the error was due to inaccurate or omitted information from the recipient of the allowance or benefit.