The 24 Hour Rule: Your Free Cancellation Window for Booking Flights

It might sound too good to be true, but this is real.
On any flight that touches U.S. soil – no matter the airline, where you're coming from, or heading to – you can cancel your flight for free within 24 hours of when you booked it.  The U.S. Department of Transportation established this federal rule way back in 2011.
This little-known rule comes with some caveats, and we'll get into those later. But consider this your “book first, ask questions later” policy. For those times you see a great flight deal or an insane mistake fare but aren't sure whether it will work – or just blank on a previous commitment for a flight you just booked – this can be a real lifesaver.
 
 
24-Hour Booking Cancellation, or a Hold?
There are a few different ways that airlines have gone about honoring this rule.
The 24-hour cancellation option is the one you’ll encounter most often. Any flight operating (even just starting or ending) in the United States has to give travelers the option to cancel for a full refund and no additional fees.
 
Delta's cancellation policy
 
But a few airlines allow the hold option, allowing you to lock in the current price before booking. The hold time is typically 24 hours. That gives you time to check for cheaper fares or confirm travel plans before you have to pay anything. Once you commit to purchasing the ticket, everything can be completed online. Before the 24-hour hold is up, you will need to pay for your ticket or it will be canceled. 
 
Qatar Airways features up to 72-hour holds
 
Things to Consider with the 24-Hour Cancellation Rule
Before you grab that hot flight deal, there are a couple of things to look out for:

Book directly with the airlines: Strictly speaking, this rule only applies to tickets booked directly with the airline. So it's always best to search using Google Flights , and then book direct if there's any possibility your plans may change.
Some OTAs follow, others don't: Travel agencies are not subject to the same DOT law as carriers. If you’re booking airfare through a third party, double-check their cancellation policies before booking. The good news is that most major online travel agencies like Priceline and Expedia typically offer 24-hour cancellations. Smaller ones found through Momondo and Skyscanner generally don't, so beware. It is one of the big reasons we suggest to skip the OTA and book directly with the airline if possible. 
This is an either/or rule: Airlines generally don't offer both a hold and a 24-hour cancellation window, and they typically don’t work together.
Miles are not mentioned: Though many airlines refund rewards or miles too, this is not explicitly required by the DOT rule. Make sure to understand your carrier's rules before booking an award ticket. Generally speaking, mileage bookings are more flexible than cash bookings. 

 
Exceptions to the 24 Hour Rule
While the 24-hour rule is fairly encompassing, there are some important caveats. Most notably, flights booked very close to departure may not be eligible for a full refund within 24 hours of booking.
The Department of Transportation's guidelines officially says that this policy is only necessary for flights booked at least seven days before departure. But some airlines are more generous. As an example, here is how each of the major U.S. airlines approaches these last-minute bookings:

Alaska:  Must be booked at least 24 hours prior to departure.
American: Must be booked at least two days prior to departure.
Delta: Must be booked at least three days (or 72 hours) prior to departure.
JetBlue:  Must be booked at least a week prior to departure.
Southwest: The 24-hour rule applies to all bookings.
United: Must be booked at least a week prior to departure.

Be sure to read up on your airline's individual policy before buying your ticket to know whether the 24-hour cancellation window will apply.
It's also important to note that while you may not be eligible for a full refund if you change your plans more than 24 hours after booking, most airlines are now offering free cancelation for a voucher – as long as you book at least a main cabin fare. That means if you want any flexibility, you'll want to avoid basic economy.
 
Bottom Line
Whether you're flying within the U.S. or heading abroad, you'll almost always have a 24-hour window to cancel your flight and get a full refund. Remember that next time you see an insanely cheap mistake fare to book it before it disappears.
As we often say, “the hotter the deal, the shorter it lasts.” The 24-hour rule allows you to book now and ask questions later. Just be sure to read up on the airline's 24-hour cancellation policy to ensure you're covered in case plans change. Then book the ticket!