Section 12(2)(a) in The Punjab Goods and Services Tax Act, 2017
(a)the date of issue of invoice by the supplier or the last date on which he is required, under [***] [Omitted 'sub-section (1) of' by Punjab Act No. 1 of 2019, dated 8.1.2019.] section 31, to issue the invoice with respect to the supply; or