Tax Law, § 605(b)(3)
Example 1:
Taxpayer A who is domiciled in New York State and taxpayer B who is domiciled in New Jersey together create an irrevocable trust. The portion of such trust attributable to property transferred by A is a New York State resident trust and the portion of such trust attributable to property transferred by B is a New York State nonresident trust.
Example 2:
Taxpayer C creates an irrevocable trust while such taxpayer is a domiciliary of New York State. Subsequent to the creation of such trust, C moves and becomes a domiciliary of California and transfers additional property to such irrevocable trust. The portion of such trust attributable to property transferred while C was a domiciliary of New York State is a New York State resident trust and the portion of such trust attributable to property transferred while C was a domiciliary of California is a New York State nonresident trust.
Example 3:
D, who is domiciled in Canada, creates an irrevocable trust with the X Trust Company in New York City as trustee. The entire corpus of the trust consists of securities of American corporations, which are actively traded by the trustee on the New York Stock Exchange. The beneficiaries of the trust are all New York State residents. Regardless of whether the trust is held to be a resident of the United States for Federal income tax purposes, it is, for New York State income tax purposes, a nonresident trust.
N.Y. Comp. Codes R. & Regs. Tit. 20 § 105.23