N.Y. Comp. Codes R. & Regs. tit. 20 § 105.1
Tax Law, § 605(a)(1)
Absence of Federal accounting period. A taxpayer who is not required to file a Federal income tax return, but who is required to file a New York State personal income tax return, must report on the calendar year basis unless the Department of Taxation and Finance authorizes the use of a different taxable period. This rule does not apply, however, in a case where a taxpayer had for a previous year filed a Federal income tax return and such taxpayer's taxable year for Federal income tax purposes for the last such year, in respect of which a Federal income tax return was filed, was other than the calendar year. Thus, where the last Federal income tax return filed by a taxpayer was on the basis of a fiscal year ending June 30th, and such taxpayer is not required to file a Federal income tax return for the subsequent taxable year, but is required to file a New York State personal income tax return, such taxpayer's taxable year for New York State personal income tax purposes for such year and thereafter is a fiscal year ending June 30th. Where a taxpayer not required to file a Federal income tax return is subsequently required to file a Federal income tax return, and the taxable year for Federal income tax purposes is different from the taxable year established for New York State personal income tax purposes, such taxpayer's New York State taxable year will be changed to conform to the Federal taxable year.
N.Y. Comp. Codes R. & Regs. Tit. 20 § 105.1