4. Determination of point of taxation in case of  change in effective rate of tax. - Notwithstanding anything contained in rule 3, the point of taxation in cases where there is a change in effective rate of tax in respect of a service, shall be determined in the following manner, namely:-

(a)     in case a taxable service has been provided before the ⁵[change in effective rate of tax],-

(i)  where the invoice for the same has been issued and the payment received after the ⁶[change in effective rate of  tax], the point of taxation shall be date of payment or issuing of invoice, whichever is earlier; or

(ii)  where the invoice has also been issued prior to ⁷[change in effective rate of  tax] but the payment is received after the ⁸[change in effective rate of  tax], the point of taxation shall be the date of issuing of invoice; or

(iii)  where the payment is also received before the ⁹[change in effective rate of  tax], but the invoice for the same has been issued after the¹⁰[change in effective rate of  tax], the point of taxation shall be the date of payment;

(b)  in case a taxable service has been provided after the ¹¹[change in effective rate of  tax],-

(i)  where the payment for the invoice is also made after the ¹²[change in effective rate of  tax] but the invoice has been issued prior to the¹³[change in effective rate of  tax], the point of taxation shall be the date of payment; or

(ii) where the invoice has been issued and the payment for the invoice received before the ¹⁴[change in effective rate of  tax], the point of taxation shall be the date of receipt of payment or date of issuance of invoice, whichever is earlier; or

(iii) where the invoice has also been raised after the ¹⁵[change in effective rate of  tax]  but the payment has been received before the¹⁶[change in effective rate of  tax], the point of taxation shall be date of issuing of invoice.