Since the KF doesn't have a 3G phone there is never any charges for Whispernet sending of documents. I've been Whispernetting docs to my K3, K4, and KF and have never had any charges because they are all three WiFi only. In all the years I've owned Kindles, I've only been charged once for Whispernetting via 3G, and that was $0.15 way back in 2009 when I had a K3 with 3G. Amazon clearly stated we would be charged but they rarely did charge us.