I know we have many seasoned SWA travelers on the board and they know all the rules about rebooking, so this is for the newbies. Back in June, I booked Vegas for Christmas and I used credits from a flight that went down in price on February 22, 2013. It was a $40 credit. Today, the return flight on Christmas Day dropped $50, so I went to rebook the same flight at the lower price. Great, except my new $50 credit expires in Feb 22, 2014 because even though it was booked in June, the expiration on this confirmation number goes back to the original credit date in Feb. I got the $50 credit, good until Feb 22nd, but I already have Feb Vegas booked and you can't apply credits to an already booked trip. Unlike SWA vouchers which can be used by other people, not just the name of the ticket holder, credits can only be used by the named ticket holder. If it was a $100 credit, I'd be tempted to add a January trip somewhere, but not for $50. Hopefully, this is some useful info about how the SWA system works and I didn't make it too confusing.