I'm not specifically familiar with AZ 529/QTP deduction rules. Most states allow a rollover of excess current year 529 contributions to following years for deduction. A quick internet search seems to indicate that AZ does not allow a rollover. Neither the AZ 529 site or the AZ DOR site address the issue. That lack of guidance and the fact that TurboTax won't let you enter more than $4000 makes me think it's not allowed.
You may want to call AZ DOR (Dept. of Revenue) to get a specific answer and/or raise the issue. It sounds like an oversight to me. The deduction rule appears to be fairly new.
