Section 4(2)(a) in The Punjab General Sales Tax (Amendment and Validation) Act, 1987
(a)where such supply has been made by any restaurant or eating house (by whatever name called) at any time on or after the 7th day of September, 1978 and before the commencement of the Punjab General Sales Tax (Amendment) Act, 1987 and the aforesaid tax has not been collected on such supply on the ground that no such tax could have been levied or collected at that time , or