If you're not on a scholarship that covers tuition you will be charged a $950 PER credit (if an OOS student) overload fee for anything over 16 hours a semester.
I forget who posted about it on here last year but at the time we didn't know about it and had registered for 17 hours. Sure enough when we looked at his bill he was charged the extra $950. We made a few last minute drop/adds and got him down to 16 and the charge went away.
I don't criticize UA about much but I think this is an absolute travesty. Full time tuition should cover up to 18 hours like it has always included in the past. Not sure when the change was made but I know it's been within the last few years.