Originally Posted by
Stranger
Other issue might be that some fares require the return to be within x months, in this instance, possibly 6 months. Changing to a later date may invalidate that condition. I believe the fare is then recalculated for the whole round trip.
This is an important factor that even savvy FFs may not be aware of, especially on a partially used ticket. Often times it works out cheaper to just obtain partial refunds and then book another ticket rather than trying to change the travel dates.
Of course when you call AC, after travel has already commenced, to cancel the remainder and retain the credit to rebook, AC agents never disclose the T&Cs down to this level of detail.