Section 15(1) in The U.P. Urban Buildings (Regulation of Letting, Rent and Eviction) Act, 1972
(1)Every landlord shall, on a building falling vacant by his ceasing to occupy it or by the tenant vacating it or by release from requisition or in any other manner whatsoever, give notice of the vacancy in writing to the District Magistrate not later than seven days after the occurrence of such vacancy, and such notice may at the option of the landlord be given before the occurrence of the vacancy.
