This amount shall consist of the amount deemed necessary to provide for payment in full of (i) all estimated obligations of each participating employer for the current fiscal year of the retirement systems and (ii) any additional obligation, plus interest on such amount, for fiscal years preceding the current fiscal year. If as a result of the amount determined to be paid for any fiscal year, a participating employer overpaid its actual obligation to the retirement system for that year, the amount to be determined by the comptroller for the next succeeding November fifteenth shall reflect the amount of the overpayment, plus interest as defined in section three hundred sixteen of this article on such amount, as a reduction in the amount otherwise required to be paid by such participating employer.
N.Y. Retire. and Soc. Sec. Law § 317