Section 20B(3)(b) in The Slum Areas (Improvement And Clearance) Act, 1956
(b)if the building has been re-erected, an annual rent of a sum equivalent to four per cent. of the aggregate cost of reconstruction of the building and the cost of the land on which the building is re-erected. Explanation.- For the purposes of this clause, the cost of the land shall be deemed to be a sum equivalent to the compensation payable in respect of the land if it were acquired under section 12 on the date of commencement of the reconstruction of the building.