GST exemption for air passenger services under viability gap funding at regional connectivity airports expires after a specified period post-commencement. Exemption from GST covers passenger air transport services provided to the Central Government, embarking from or terminating at a regional connectivity scheme airport, where consideration is in the form of viability gap funding. The exemption is time-bound and ceases to apply on or after the expiry of the period measured from the date of commencement of operations of the regional connectivity scheme airport as notified by the Ministry of Civil Aviation; the temporal period has been amended from the earlier shorter term.