What
@wanderlust7 said
I was writing and got distracted and the words were taken right out of my mouth.
But for sure AmEx doesn't change your card anniversary with product changes. They just prorate AFs for mid year product changes. What I recall happened when we were offered a waived AF is they give you the full year for free and then prorated the next part of the year until your anniversary. (like Jan anniversary, upgrade Jun for waived AF, next Jan no fee, next Jun charged for the 6 months until next anniversary)