- Notwithstanding anything contained in section 12 or section 13, the time of supply, where there is a change in the rate of tax in respect of goods or services or both, shall be determined in the following manner, namely:—

(a) in case the goods or services or both have been supplied before the change in rate of tax,—

(b) in case the goods or services or both have been supplied after the change in rate of tax,—