United Airlines Provides a 24-hour cancellation Policy ＋𝟭.𝟴𝟲𝟲:𝟴𝟴𝟰.𝟯3.𝟭𝟱. If you book a flight at least seven days before deParture and cancel within 24 hours of booking (【+𝟭.𝟴𝟲𝟲:𝟴𝟴𝟰.𝟯3.𝟭𝟱】) (𝙾𝚃𝙰)]), you are eligible for a full refund without any cancellation fees.