N.Y. Suffolk County Tax Act § 47
The purchasers at such sale shall pay to the county treasurer the full amount of the bid therefor within one week from the date of such sale, and thereupon the county treasurer shall execute to each purchaser, including the county, a certificate in writing which shall contain a description of the real estate purchased, the amount paid therefor, the interest or penalty thereon at which such property was bid, the date of the sale and that the same was sold for unpaid town, county and state taxes or assessments as the case may be, the name of the owner of such property as it appears on the books, and such other information as the county treasurer shall deem expedient. Such purchaser or his heirs and assigns may, at any time after the time limited in section forty-nine and section fifty-two of this act for the redemption of such premises shall have expired, and the notice therein provided has been given, and said premises shall not have been redeemed as therein provided and title to such premises shall have been conveyed to him as herein provided, and not before, obtain actual possession of the premises by an action at law or by causing the occupant of such real estate to be removed therefrom, and the possession thereof to be delivered to him in the same manner, and in the same proceedings, and before the same officers as in a case of a tenant holding over after the expiration of his term without the permission of his landlord.
N.Y. Suffolk County Tax Act § 47