Originally Posted by anabolism

I thought taxes (and fuel surcharges) are recalculated for all voluntary changes, before or after departure, reroute or not (even just switching carriers). But this works both ways -- if the tax/surcharge has gone down you get a refund (unlike price changes).

Big difference is if the price for your origin has changed. For example, the ex-JNB price went up a lot this year. I have a 2014 ex-JNB ticketed at the old price. My understanding is that if I change the route before departure, I'll have to pay $125 plus the price increase, but if I change it after the trip has started I only have to pay the $125 (plus any tax differences).

Am I misunderstanding the rules?