Southwest Airlines is known and loved for its lack of fees. As part of the airline’s “Transfarency” policy, all Southwest passengers can change or cancel their flight with no fee.

But, there’s one aspect of Southwest’s super-flexible change policies that’s not as well known: Southwest will credit you the fare difference if the price of your flight drops. This means you can book Southwest flights without worrying about the flight getting cheaper. Book a flight now, then claim any price difference if the fare drops in the future.

However, this refund isn’t automatic. You’ll need to keep an eye out for price changes and actively request the fare difference when the price reduces. The good news is that process is relatively easy.

Here's how to rebook so you can snag cheap Southwest flights when prices drop.

Does Southwest charge to change flights?

All Southwest flight bookings can be changed or canceled without fees. Unlike other U.S. airlines — which are just loosening up change fee restrictions — Southwest doesn’t exclude the cheapest fares or require that your flight originates in a certain country.

Though Southwest doesn’t sell basic economy tickets, even its lowest fare (Wanna Get Away) doesn’t require you to pay more to be able to change or cancel your flights later. This isn’t the case when flying American, Delta or United.

Simply put: You can always modify any Southwest flights for free, no matter the ticket level.