Drawback effective date: retrospective drawback applies from government notification tied to input duty or service tax changes. The Central Government may specify the period for which a drawback amount or rate fixed or revised under the rules remains in force. Retrospective drawback is effective from the date specified by government notification in the Official Gazette, not earlier than the date of changes in duty on inputs or tax on input services used in export goods. Statutory provisions determine the applicable drawback amount or rate for exports.