Section 178(2) in Gauhati Municipal Corporation Act, 1971
(2)The said duty shall be levied -(a)In the form of a surcharge on the duty imposed by Indian Stamp Act, 1899 as in force for the time being in the State, on every instrument of the description specified below; and(b)At such rate as may be determined by the Corporation not exceeding five per cent on the amount specified below against such instruments; -Description of instrument. - Amount on which duty should be levied.(i)Sale of immovable property. - The amount or value of the consideration for the sale, as set forth in the instrument.(ii)Exchange of immovable Property. - The value of the property of the greater value, as set forth in the instrument.(iii)Gift of immovable property. - The value of the property as set forth in the instrument.(iv)Mortgage with possession of immovable property. - The amount secured by the mortgage as set forth in the instrument.(v)Lease in perpetuity of immovable property. - The amount equal to one-sixth of the whole amount or value of the rent, which would be paid or delivered in respect of the first fifty yeas of the lease as set forth in the instrument.