Originally Posted by
mtkeller
The last anecdote I heard was that they were no longer collecting the surcharges on KE (happened about the time the VA surcharges disappeared), but still collecting on some partners like CZ. If you change an existing award, they re-do the taxes/fees and it will wind up being whatever they're currently charging/collecting (and so if foreign taxes are converted to USD, you'll likely see a change in the taxes/fees because of simple currency fluctuations).
I would expect the fees to be recalculated every time an award ticket is reissued. For instance, if you switch from a nonstop to a connection, this can raise the fees by a small amount. Any recalculation will be based on the current rates and policy.
It should be easy to ask about any change in fees when calling to check availability, so that you can decide whether any additional fees are worthwhile before committing to the change and losing your current award seats.