N.Y. YTS Law § 15-103

§ 15-103. Change of residency status.\n A. General. If an individual changes his/her status during his/her\ntaxable year from City of Yonkers resident to City of Yonkers\nnonresident, or from City of Yonkers nonresident to City of Yonkers\nresident, he/she shall file one (1) return as a City of Yonkers resident\nfor the portion of the year during which he/she is a City of Yonkers\nresident and a return under Article X of this chapter for the portion of\nthe year during which he/she is a City of Yonkers nonresident, subject\nto such exceptions as the State Tax Commission may prescribe by\nresolution.\n B. Computation for resident individuals. If an individual's period of\nCity of Yonkers residence is not the same as his/her period of state\nresidence, his/her net state tax for the portion of the year during\nwhich such individual is a City of Yonkers resident shall be determined\nas if his/her state period of residence was the same as his/her city\nperiod of residence.\n C. Trusts. If the status of a trust changes during its taxable year\nfrom City of Yonkers resident to City of Yonkers nonresident, or from\nCity of Yonkers nonresident to City of Yonkers resident, the fiduciary\nshall file one (1) return as a City of Yonkers resident trust for the\nportion of the year during which the trust is a City of Yonkers resident\ntrust and a return under Article X of this chapter for the portion of\nthe year during which the trust is a City of Yonkers nonresident trust,\nsubject to such exceptions as the State Tax Commission may prescribe by\nregulations.\n D. Computation for resident trusts. If a trust's period of City of\nYonkers residence is not the same as its period of state residence, its\nnet state tax for the portion of the year during which such trust is a\nCity of Yonkers resident trust shall be determined as if its state\nperiod of residence was the same as its City of Yonkers period of\nresidence.\n