Section 14(b) in The Punjab Goods and Services Tax Act, 2017
(b)in case the goods or services or both have been supplied after the change in rate of tax,-(i)where the payment is received after the change in rate of tax but the invoice has been issued prior to the change in rate of tax, the time of supply shall be the date of receipt of payment; or(ii)where the invoice has been issued and payment is received before the change in rate of tax, the time of supply shall be the date of receipt of payment or date of issue of invoice, whichever is earlier; or(iii)where the invoice has been issued after the change in rate of tax but the payment is received before the change in rate of tax, the time of supply shall be the date of issue of invoice:
