N.Y. Comp. Codes R. & Regs. tit. 20 § 363.1
In any case in which a Federal estate tax return has been filed for an estate, the legal representative of such estate, or any person having actual or constructive possession of any property includible in the New York gross estate, shall submit to the office of the Tax Commission any information, records, documents and statements, or copies thereof, within 20 days after request therefor is made. The State Tax Commission may audit the Federal estate tax return of any estate at any time before or after an order has been entered fixing tax, provided that a final Federal determination has not been made. The State Tax Commission shall notify the executor upon commencement of audit pursuant to this regulation.
N.Y. Comp. Codes R. & Regs. Tit. 20 § 363.1