Revision of fair rent

(a) When the fair rent of a building has been fixed, no further increase in such fair rent shall be permissible except where some necessary addition, improvement or alteration has been carried out at the landlord's expense. (b) If any such addition, improvement or alteration consists of the installation of fittings or machinery which has been excluded from valuation for the purpose of the property tax or house tax, the fair rent fixed may in proper cases be enhanced, but shall in no case exceed by more than fifteen per centum, the monthly rent as fixed before the date of the application. Provided that in cases where an order under clause (c) or clause (d) of sub-section (6) is taken under this sub-section, the monthly rent on the basis of which the property tax or house tax was fixed immediately before the date of the application shall be the basis for the increase.