N.Y. Real Prop. Tax Law § 842

§ 842. Computation of county equalization rates. The commissioner\nshall compute county equalization rates for each county to which this\ntitle is applicable by furnishing the final state equalization rates\nwhich are established pursuant to article twelve of this chapter for\neach city and town in the county for the final assessment roll to be\ncompleted and filed during the current year or, if such rates are not\nthen available for each city and town in the county, by adjusting the\nfinal state equalization rate established pursuant to article twelve of\nthis chapter for each city and town in the county for the final\nassessment roll required to be completed and filed during the prior\ncalendar year by the appropriate "change in level of assessment", if\nany, as that term is defined in section twelve hundred twenty of this\nchapter. On or before the fifteenth day of November, or such other date\nas may be prescribed by law for the determination of county equalization\nrates, the commissioner shall certify the county equalization rates to\nthe clerk of the legislative body of each county to which this title is\napplicable. Within five days of the receipt of such rates, the clerk of\nthe legislative body shall provide to each city and town a written\nnotice of the county equalization rates computed by the commissioner.\n