Jason Buhlman posted this:
Fifth, there are a few pieces of early errata that we need to get up immediately.
All PCs are trained in being unarmored.
Does that mean they get their level to AC when not wearing any armor?
The rules state:
If you’ve been trained in the statistic or item, your
proficiency modifier is equal to your level.
That is correct, yes. Being Trained in Unarmored means that, when wearing no armor, you'd just add your Proficiency Modifier to Dex and Base 10. No AC or TAC bonuses apply.
So an 8th level Wizard with Dex 14 would be:
Base 10 + 8 (Trained Proficiency Modifer) + 2 (Dex) = 20
This applies to all classes except the Monk, because they have higher Proficiency than Trained (they start at Expert).
Well in one way it does raise your ac because prior to that everybody was untrained in it which is a -2 to your check. Even being untrained though everybody got their level to their AC. It is just when you are untrained it is your level -2.