N.Y. GCT Law § 25-A

§ 25-a. Authorization to impose tax.-- In addition to any other taxes,\nnow authorized by law, any city having a population of one million or\nmore is hereby authorized and empowered to adopt and amend local laws\nimposing a tax on the personal income of residents of such city to be\nadministered in the manner provided for in this article by the\nadministrator as defined in section one of the model local law\nhereinafter set forth.\n The tax authorized by this article may be imposed only if the general\ncity law authorizes the adoption of a city tax on the earnings of\nnonresidents and the city imposing the tax herein authorized also\nimposes such tax on the earnings of nonresidents. The rates of such tax\nshall be the rates contained in either section three or three-A of the\nmodel local law and such rates may be reduced and increased, provided\nthat the rates shall not be fixed higher than those contained in section\nthree-A of such model local law.\n The terms of such local law shall be substantially the same as the\nfollowing model local law except that:\n (a) Any such local law may include a provision for the specific credit\nfor individuals described in section twenty-five-b of this chapter\neffective for any taxable year commencing on or after July first,\nnineteen hundred sixty-seven;\n (b) Any such local law may be amended to conform it with similar\nprovisions of article twenty-two of the tax law except insofar as it\nrelates to nonresidents as presently in effect or as it may be amended;\nand\n (c) The appendix in such local law may be amended for the purpose of\nconforming it with the United States internal revenue code or other\nfederal laws relating to taxation as presently in effect or as they may\nbe amended.\n