If you don’t check in 24 hours before your flight, several issues may arise that could impact your travel plans. Most airlines open online check-in 24 hours before departure, and failing to complete this step in that window can lead to delays, limited seat options, and sometimes even denied boarding. Online check-in helps secure your seat assignment, verify travel documents, and speed up the airport process. When passengers skip this step, they must check in at the airport, which may involve long lines, especially during peak travel times. Additionally, by not checking in early, you may miss the opportunity to select or change your seat, and airlines may assign you a less favorable one, especially if the flight is nearly full. In some cases, passengers who don’t check in early may be flagged as potential no-shows, prompting the airline to release their seat to standby passengers. This is more likely on oversold flights, where airlines rely on confirmed check-ins to finalize seating. While most airlines still allow airport check-in at staffed counters or kiosks, these usually close 30 to 60 minutes before domestic flights and 60 to 90 minutes before international flights. Missing the check-in deadline can result in being denied boarding, even if you’ve arrived at the airport. Some budget airlines may also charge a fee for checking in at the airport if online check-in was available and not used in advance. Not checking in early can also slow down your entire airport experience. Without an online boarding pass, you’ll need to stop at the counter, and if you're checking baggage, you risk delays at the bag drop. Those flying with carry-on only who skip early check-in lose the benefit of heading straight to security. If there are any issues with your booking—such as passport expiry, visa validation, or other document mismatches—early check-in gives you time to resolve them. Waiting until the last minute can lead to complications that may prevent you from boarding on time. Moreover, many airlines use the check-in process to send last-minute updates, gate changes, and flight alerts, so skipping check-in can also mean missing out on crucial travel information. In some cases, passengers who fail to check in in time and miss their flight may not be entitled to a refund or rebooking without a fee. Every airline has different rules, but most emphasize the importance of checking in no later than the cut-off time. To avoid these issues, travelers should always aim to check in as soon as the 24-hour window opens, confirm all travel details, and download or print their boarding pass. This simple step reduces risk, saves time, and ensures you’re ready to travel. In conclusion, not checking in 24 hours before your flight can lead to unwanted complications, limited seating, missed flights, and additional fees. Checking in on time ensures smoother processing, better seat options, and peace of mind as you prepare to board.