If a flight is overbooked and no one accepts the airline's offer of vouchers or cash to take a later flight, the airline will proceed with Involuntary Denied Boarding (IDB). In 2026, airlines use a "priority list" to decide who gets "bumped." This list typically prioritizes passengers based on their frequent flyer status, the fare class paid (higher fares are safer), and the time of check-in (last to check-in are often first to be bumped). However, if you are bumped involuntarily, you are legally entitled to significant cash compensation—often up to $1,550 or 400% of your one-way fare under U.S. and EU regulations—provided the airline cannot get you to your destination within a few hours of your original time. Airlines must also provide meal vouchers and hotel accommodations if the delay is overnight. It is a high-stress situation, but the legal protections for "involuntary" passengers are much stronger than for those who volunteer.