Originally Posted by
emma dog
Even this isn’t that simple. It’s $75 if your fare class is still available. Otherwise you have to pay up to that fare class AND pay $75 for confirmed standby.
The most impactful exception is if you have a confirmed F seat on a domestic flight.
If original booking class is not available, you should just have to pay fare diff (which will also take into account things like advance purchase requirements on fares in addition to fare class availability), not fare diff + $75 to confirm on new flight. Since Main fares don't have change fees, it shouldn't really be any different than making a change prior to same-day change window where you will also just be charged fare diff.