Missing your check-in deadline (which is typically 45–60 minutes before departure for domestic and 90–120 minutes for international) essentially results in a "No Show" status. Once the check-in counter closes, your seat is released, and your ticket is technically voided. However, most major airlines in 2026 operate under an informal "Flat Tire Rule": if you arrive at the airport within two hours of your missed flight, a gate agent may rebook you on the next available flight for just a "rebooking fee" rather than the cost of a full new ticket. If you miss check-in due to your own error, you may lose the entire value of your fare. Crucially, if you miss the first leg of a multi-segment or round-trip ticket, many airlines will automatically cancel all subsequent legs of the journey. In 2026, the best course of action is to call the airline or use their app before the check-in window closes to explain your delay, which significantly increases your chances of a free or low-cost rebooking.