Specified premises designation affects IGST treatment for hotel accommodation, enabling opt in/out declarations and annual filing requirement. Amendment substitutes the definition of specified premises for IGST rate purposes effective 1 April 2025, defining such premises as those meeting a preceding year per unit tariff threshold, or those declared as specified premises by a registered supplier between 1 January and 31 March of the preceding financial year, or declared by a registration applicant within fifteen days of registration acknowledgment. The amendment inserts Annexures VII-IX prescribing standard opt in and opt out declarations, requires separate filings per premises, and provides that declarations apply for the stated financial year and continue thereafter unless rescinded.