Section 99A(2) in The Gujarat Municipalities Act, 1963
(2)For the purpose of levy of tax on buildings or lands situate within the municipal borough under sub-section (1)-(a)the buildings may be classified into residential buildings and buildings other than the residential buildings; and(b)the municipality may determine one rate of tax for residential buildings and the other rate of tax for buildings other than the residential buildings:Provided that it shall be lawful for the municipality to determine for residential buildings, the carpet area of which does not exceed forty square metres, such rate of tax as is lower than the rate of tax determined for residential buildings generally:Provided further that the rates of tax per square metre of carpet area shall be decided by the municipality with the approval of the Director of Municipalities.