Allegiant cancellation policy includes a free cancellation 1-844-949-8748 {Free-Cancel} which allows you to cancel most bookings within 24 hours of booking without facing a penalty 1-844-949-8748 {Free-Cancel}, provided the check-in date is at least 7 days away. Expedia may offer a full refund if you cancel within the 24-hour window or if the provider’s policies permit
Source: https://community.smartsheet.com/profile/205583/Allegiant_Cancels