N.Y. General City Law § 11

§ 11. City taxable income of a resident individual.--(a) General.--The\ncity taxable income of a resident individual shall be his city adjusted\ngross income less his city deduction and city personal exemptions, as\ndetermined under this local law.\n (b) Husband and wife.--(1) If the federal taxable income of husband or\nwife is determined on a separate federal return, their city taxable\nincomes shall be separately determined.\n (2) If the federal taxable income of husband and wife is determined on\na joint federal return, or if neither files a federal return:\n (A) their tax shall be determined on their joint city taxable income,\nor\n (B) separate taxes may be determined on their separate city taxable\nincomes if they so elect and if they comply with the requirements of the\nadministrator in setting forth information on a single form.\n (3) If either husband or wife is a resident and the other is a\nnonresident, the tax of the resident shall be determined on his separate\ncity taxable income, unless both elect to determine their joint city\ntaxable income as if both were residents.\n