Notification amendment under section 148 extends the covered period and postpones the compliance deadline for SGST provisions. Amendment to a State GST notification substitutes wording in the second proviso of paragraph 2 to extend the covered interval to include July 2017 through December 2018 and to postpone the compliance cutoff to the 31st day of March, 2019, thereby expanding the temporal scope of the proviso and delaying the applicable deadline.