N.Y. Comp. Codes R. & Regs. tit. 20, § 154.1
(a) If an individual changes resident status during the taxable year from resident to nonresident or from nonresident to resident (including an individual domiciled in New York State who meets the requirements of section 605[a][1][B] of the Tax Law and is therefore considered to be a nonresident for part of a taxable year), such individual must file two New York State personal income tax returns for that year. One New York State personal income tax return must be filed on form IT-201 for the resident portion of the year, and another New York State personal income tax return must be filed on form IT-203 for the nonresident period if such individual meets any of the following conditions:
(1) Such individual's New York adjusted gross income from all sources during the resident period plus such individual's New York adjusted gross income from New York State sources during the nonresident period equals or exceeds:
(6) Such individual wishes to obtain a refund, even though a New York State personal income tax return or returns would not otherwise be required in accordance with the foregoing conditions. (See section 151.5 of this Article regarding the filing of New York State personal income tax returns as claims for refund or credit.)
(b) Exception.
(1) An individual who is required to file two New York State personal income tax returns for the taxable year in accordance with the provisions of subdivision (a) of this section is not required to file a New York State personal income tax return for the taxable period (either prior to or subsequent to the change of residence) during which such individual meets all of the following conditions: In lieu of the New York State personal income tax return otherwise required to be filed for the taxable period in which such individual met all of the conditions contained in subparagraphs (i)-(iii) of this paragraph, such individual must attach a statement to or indicate on the New York State personal income tax return required to be filed to the effect that for the other taxable period such individual met all of these conditions (see also section 151.6[a][2] of this Article). However, all of the applicable sections of this Part must be taken into account on the New York State personal income tax return which is required to be filed in accordance with this subdivision. This includes, but is not limited to, the special accruals required by section 154.10 of this Part.
Tax Law, § 654(a)