Extension of deadline under State GST notification postpones earlier compliance date to a subsequently specified date. Amendment substitutes the prescribed date in Notification No. 8/2023 State Tax with a newly specified date by Notification No. 26/2023 State Tax; the substitution of the words, letter and figure of the earlier date with the new date is the operative mechanism. The notification states the amendment shall be deemed to have come into force retrospectively from the earlier specified date, fixing the effective commencement of the substituted deadline for all purposes of the principal notification.