5 CFR 841.505 - Correction of error.
(a) When it is determined that an agency has paid less than the correct total amount of the normal cost for any or all of its current or past employees, for any reason whatsoever, including but not limited to, coverage decisions, correction of the percentage applicable or of the amount of basic pay, or additional payment of basic pay, the agency must pay the total additional amount payable under 5 U.S.C. 8423 and subpart D of the this part to the Fund.
(c) The payment to the Fund described in paragraph (a) of this section shall be made as soon as possible, but not later than provided by standards established by OPM, regardless of whether or when the portion which should have been deducted from employee basic pay is recovered by the agency.
(d) Any portion of the payment to the Fund described in paragraph (a) of this section which should have been deducted, but was not, from employee basic pay constitutes an overpayment of pay, subject to collection by the agency from the employee, unless waived under applicable authority such as 5 U.S.C. 5584.