Section 8(8)(b) in The Central Sales Tax Act, 1956
(b)the sale price of all goods returned to the dealer by the purchasers of such goods,-(i)within a period of three months from the date of delivery of the goods, in the case of goods returned before the 14th day of May, 1966;(ii)within a period of six months from the date of delivery of the goods, in the case of goods returned on or after the 14th day of May, 1966: