This notice provides guidance to U.S. and foreign air carriers regarding compliance with the customer service rule that requires carriers to hold a reservation at the quoted fare for 24 hours without payment or allow a reservation to be cancelled within 24 hours without penalty (the “24- hour reservation requirement”). The 24-hour reservation requirement is mandated by the Department of Transportation’s consumer rule “Enhancing Airline Passenger Protections” (14 CFR 259.5(b)(4), 76 Fed. Reg. 23110, 23166, Apr. 25, 2011) and applies to all reservations made seven days or more prior to the flight’s scheduled departure time.1 To comply with the regulation, carriers may not deceive consumers about the 24-hour reservation requirement when consumers inquire about cancelling or changing a reservation within 24 hours of making or paying for that reservation. This guidance also clarifies that the Department’s Office of Aviation Enforcement and Proceedings (Enforcement Office) considers the failure to notify such consumers of the 24-hour reservation requirement to be unfair and deceptive in violation of 49 U.S.C. § 41712. It also considers the failure to offer a passenger a full refund in the original form of payment in the event of a cancellation request covered by the 24-hour reservation requirement to be an unfair and deceptive practice.