Section 9(2)(a) in The Bombay Rents, Hotel and Lodging House Rates Control Act, 1947
(a)Notwithstanding anything contained in sub-section (1), but subject to the provisions of clauses (b) and (d), a landlord shall further be entitled to make an increase in the rent of premises by an addition to the rent in the manner prescribed i,f an amount of not exceeding fifteen per cent. per annum of the expenses incurred on account of special additions to premises of special alterations made therein or additional amenities provided for the premises or on account of improvements or structural alterations made under sub-section (1) : 18 of 1987, s. 7.