New York Consolidated Laws, Retirement and Social Security Law - RSS § 424. Distribution of earnings

At the close of each fiscal year, the average rate of investment earnings of the common retirement fund shall be computed by the actuary and certified to the comptroller.  This rate shall be determined from the investment earnings during the calendar year, which ended three months prior to the close of the fiscal year.  The amount of such earnings attributable to each retirement system shall be computed by the actuary and certified to the comptroller, who shall thereupon credit each retirement system in accordance therewith.