Retrospective exemption from integrated tax prevents collection on specified supplies and bars refunds for defined historical periods. The amendment provides that no integrated tax shall be levied or collected on supply of fishmeal for the period from 1 July 2017 to 30 September 2019, and that integrated tax at a specified rate shall be levied or collected on supply of pulleys, wheels and other parts used as parts of agricultural machinery for the period from 1 July 2017 to 31 December 2018; it further bars refunds of tax actually collected that would not have been collected had the retrospective provision been in force.