Southwest Airlines has implemented a new ‘NO SHOW’ policy on September 13, 2013.
Passengers who fail to cancel bookings on Southwest flights now face loss of the ticket's value if they don't show up. Customers who buy nonrefundable tickets must cancel at least 10 minutes before scheduled departure or forfeit the ticket's value.
In the past, there was little incentive to cancel because Southwest let customers use the value of the unused ticket toward another flight within one year. That meant seats flew empty when Southwest could have sold them to somebody else.
Southwest is still letting passengers change nonrefundable tickets ahead of time without penalty.
Southwest’s Policy (See refunds and lost tickets tab): https://www.southwest.com/html/customer-service/purchasing-and-refunds/
If you have any questions, contact the Purchasing Office at ext. 6553.