So, if you booked your tickets using your miles balance, you can easily cancel a flight, but the refund of miles will depend on the time left for the flight's departure. If your flight's scheduled departure is within 72 hours or less, you won't get any refund.

Yes, you can cancel a United Airlines flight booked with MileagePlus miles, and the process is remarkably flexible compared to many other carriers. As of 2026, United has eliminated redeposit fees for award tickets, meaning if you cancel your flight, your miles will be returned to your account for free. This policy applies regardless of how close you are to the departure date, though you generally must cancel before the flight actually takes off to avoid "no-show" penalties. When you cancel, any taxes and fees paid with a credit card at the time of booking are also refunded to the original form of payment. It is important to note that while the miles are redeposited immediately in most cases, they retain their original expiration rules (though United miles currently do not expire as long as the account remains active). If you booked a "Money + Miles" ticket, the rules are slightly more rigid; you can still cancel for a full refund of both components within the 24-hour flexible booking window, but after that, the "money" portion may only be returned as a future flight credit rather than cash.