You can almost always cancel a flight 3 days before departure, but whether you get a refund or just a credit depends on your ticket type. In 2026, "Basic Economy" tickets are typically non-refundable and non-changeable, meaning you likely lose the entire fare. However, "Standard Economy" and "Refundable" tickets allow you to cancel for a full refund (to the original payment) or a Future Flight Credit. Most airlines no longer charge "change fees" for standard tickets, but you must still pay the fare difference if rebooking. If you have "Cancel for Any Reason" travel insurance, you can recoup 50-75% of the cost. The only "hard" rule is the 24-hour window, which only applies if you booked the flight more than a week in advance; by the 3-day mark, that grace period has long since passed.