N.Y.C. Admin. Code tit. 27, ch. 2 § 27-2099

a. When the owner of a dwelling, who is required to register under this article, conveys title to the dwelling to another, the transferor shall, on the day of such transfer, notify the department by regular mail of the name, residence and business address of the new owner, or, if the new owner is a corporation, of the name and address of such corporation. The registration statement in accordance with section 27-2098 of this article shall be presented by the new owner to the office of the register of the city of New York, or the county clerk as required by subdivision c of this section if such owner records such deed, or to the department if the deed is not recorded, and in no event more than five days from the date of taking of title; however, the failure by a new owner to file such registration statement shall not impair the validity of his or her title.


b. When the ownership of a dwelling changes by operation of law, the new owner, if required to register, shall file a registration statement in accordance with section 27-2098 of this article not more than thirty days from the date that title devolved upon him or her.


c. The office of the register of the city of New York or county clerk shall not record or accept for recording any deed transferring title to real property or a lease or memorandum of lease of an entire multiple dwelling unless such instrument is accompanied by the registration statements required under this article, with their appropriate fees, or an affidavit stating that the deed, or lease or memorandum of lease does not affect a multiple dwelling and such registration is not required. Such registration statements and the fees therefor shall be forwarded to the department for filing and acceptance.


d. (1) Notwithstanding any other provision of law, after thirty days have elapsed from the date that title to a dwelling is conveyed to a new owner or devolves upon a new owner by operation of law, if the new owner has not filed a registration statement in relation to such dwelling, the department may invalidate the former owner's last valid registration for such dwelling upon application by such former owner for the limited purpose of service of notices or orders authorized or required under this code to be served by the department upon the last registered owner or last registered managing agent. To effect such limited invalidation, the former owner shall submit such documentation as is satisfactory to the department that the ownership of the dwelling has changed and that such former owner no longer owns the dwelling; provided, however, that such registration shall remain valid for all purposes until the department informs such former owner in writing that such registration has been invalidated for such limited purpose.


(2) Where a notice or order is authorized or required under this code to be served by the department upon the last registered owner or last registered managing agent and the department has invalidated the last valid registration pursuant to paragraph one of this subdivision for the limited purpose of service of notices or orders, such service may be made by personal delivery of the notice or order to a person in direct or indirect control of the premises or by mailing a copy thereof to the attention of "owner" or "managing agent" at such dwelling; provided, however, that such manner of service is authorized only until such time as a valid registration is subsequently filed for the dwelling.