Allegiant Air's Flight Modification Policy permits passengers to Modify their flight according to the following guidelines.If the travel flexibility option, the traveller must change their flight at least seven days before the date of departure.Allegiant costs $75 for each flight modification fee per change.All changes are final and not refundable. They are not transferable to another person.Travel credits are valid only for two years. They are not able to be renewed after expiration.Flexible travel allows passengers to change their flight up to one hour prior to departure.Byer can alter the vacation package within 72 hours of departure. A charge added to tickets that aren't refundable is known as a ticket price difference.Any cancellation or change to a flight within 24 hours of purchase are completely free.Passengers who adapt to the flexibility of travel get a travel voucher. Read Also: KLM Flight Change | Emirates Flight Change | Jetblue Flight Change