The 24-hour rule is a US Department of Transportation requirement that lets a customer cancel most air bookings without penalty within 24 hours of purchase, provided the flight was booked at least seven days before scheduled departure.
The 24-hour rule exists because the US Department of Transportation decided that a traveler who realizes a booking mistake immediately after purchase should not be locked into a non-refundable fare because of a typing error, a wrong date, or a duplicate purchase. It applies to any airline (US or foreign) selling flights to, from, or within the United States, and the seven-day advance-purchase condition is the only wide carve-out.
Airlines choose one of two ways to comply: a full refund of a completed booking within 24 hours of purchase, or a courtesy hold that lets the traveler confirm a fare quote for 24 hours before payment. Most large carriers went with the refund model, though a few still run the hold variant.
Common questions
Does the 24-hour rule apply to non-refundable tickets?
Yes. That is the point of the rule: it overrides a non-refundable fare’s rules for the first 24 hours after purchase, provided the departure is at least seven days out and the itinerary touches the United States. Outside that window, non-refundable rules apply normally.
Does the 24-hour rule apply to changes, or only cancellations?
Only cancellations. A change inside the 24-hour window still has to go through the fare rules for the new itinerary and any applicable change penalty, so the standard workaround is to cancel and rebook rather than reissue.
Is the 24-hour rule the same as the GDS void window?
No. The DOT rule is a customer-facing right against the airline; the GDS void window is an agency-side reporting mechanism that lets a ticket be pulled before it settles on the airline’s daily report. The two windows overlap but are not the same lever.