Q: I’m confused about the 24-hour airfare-hold policy. American Airlines seems to have a different rule on this compared to other airlines.

On most airlines you pay for the fare and have 24 hours to change it or get a refund, but I got burned on American because I bought the ticket instead of putting it on “hold” and now they’re requiring a $200 change/cancel fee.

Can you walk me through the rules about getting airfare refunds or changing your flight within 24 hours of booking?

A: If you are booking an airfare in the United States, U.S. Department of Transportation regulations require that, as long as you’ve booked a nonrefundable ticket seven days ahead of your flight, you’re entitled to hold your reservation and the fare and change or cancel your reservation within 24 hours of booking, without paying a change/cancel fee — typically $200 on the large “network” carriers for a domestic fare, a bit less on other airlines (but much more — up to $450 — for some international fares).

You can either cancel the reservation entirely, or change it, within the 24-hour window. If you change it, however, a fare difference may apply, but there is no change penalty. This applies not just to U.S.-based airlines, but any airline selling airfares in the U.S.

You still have to pay for the airfare, and then get a refund without penalty, except that American Airlines is a bit different in that it allows you to hold your seat and the fare for 24 hours without paying for it.

On American, you should NOT pay for the fare but merely choose the 24-hour hold option without payment. Also, American sells fare “add-ons” starting at $68 round-trip that allow you to change your flight for free at any time, and the add-on includes a checked bag round-trip and priority boarding.

Southwest Airlines lets you change or cancel a fare within the 24-hour window without penalty, but it also allows you to change or cancel a reservation anytime before flight time and get a credit for the full amount of your fare, applicable to future travel within a year of the original reservation. You will have to pay any applicable fare increase, however.

To take advantage of the 24-hour cancel or change rule, it’s best to book directly with airlines, either online or by phone, rather than through third-party websites.

And it goes without saying that you can cancel a fully refundable ticket anytime and get a refund, although if you change rather than cancel there may be a difference if the fare has changed.

One more thing: Many people don’t realize that in airline contracts of carriage, there’s a rule (often called Rule 260) about “involuntary refunds.” Basically it states that if the airline refuses to carry you for any reason, or if your flight is delayed more than a specified amount of time (121 minutes or greater on AA for example) or the flight is canceled, you can apply for a full refund, even on a nonrefundable ticket. United calls their rule on this something else, which you can see by wading through their contract of carriage.

So let’s say you buy a fare you no longer can use and the DOT 24-hour rule doesn’t apply. Your only hope to avoid the change/cancel fee is if your flight is canceled or severely delayed.

It may or may not be worth your time to show up for your flight and pray it’s canceled or significantly delayed (you do have to check in for the flight). And you can also get a refund if there’s a significant schedule change before your departure (let’s say they change you from a 9 a.m. departure to 6 a.m., or your new flight requires a much longer layover or an overnight stay, or even from a nonstop to a connecting flight).