N.Y. SCT Law § 13-C

§ 13-c. Interest rate on late payment of taxes and delinquencies. (1)\nThe amount of interest to be added on all taxes received after the\ninterest free period and all delinquent taxes shall be one-twelfth the\nrate of interest as determined pursuant to subdivision two of this\nsection.\n (2) On or before the fifteenth day of July in each year, the state\ncommissioner of taxation and finance shall determine the one year\nconstant maturity yield index for United States treasury securities for\nthe quarter year ending on the immediately preceding June thirtieth.\nSuch index, rounded to the nearest one-tenth of a percentage point,\nshall be the rate of interest prescribed by this subdivision, which rate\nshall be effective for all warrants issued for a collection period\ncommencing on or after the first day of September next succeeding the\ndate such rate of interest is determined provided, however, that such\ninterest rate shall in no event be less than twelve percent per annum.\nIn any given year for which the state commissioner of taxation and\nfinance fails to determine the rate of interest by the preceding\nfifteenth day of July, the rate of interest determined for the prior\nyear shall apply. For the purposes of this subdivision, the one year\nconstant maturity yield index for United States treasury securities for\nany quarter year shall be the average of such index during the three\nmonths constituting such quarter year, as such index is compiled by the\nUnited States department of the treasury, published by the board of\ngovernors of the federal reserve system of the United States and\nexpressed in terms of interest percentage per annum.\n