GST on airport levies: airlines may collect charges, but airport operators remain liable if pure agent conditions are met. PSF and UDF charged by airport operators are consideration for services to passengers and are subject to GST. Airlines that collect these charges act as agents; if they meet the conditions of a pure agent under Rule 33 and separately indicate the amounts, the PSF/UDF and GST thereon are excluded from the airline's taxable value and the airline need not pay GST on those sums. Airport operators remain liable to pay GST on PSF/UDF collected, while collection charges paid to airlines for collection services attract GST and are eligible for input tax credit by the airport operator.