I think we are getting to the heart of the matter. On my software, I cannot make an entry in the 4th line of that screen (i.e. the line that says "contributions for which you are taking an Arizona credit").
In my software, whatever entry I make on the first line (i.e. gifts by cash or check) automatically gets carried over to the 4th line. Entries I make on the 2nd or 3rd lines of that screen do not affect the carryover of the line 1 entry to the 4th line; the software just copies the first line entry into the fourth line.
In addition, the first three lines have boxes to type in the desired value. In my software, the fourth line does not have a box, the value entered in the first line just appears there, just to the right of the words "Learn More".
To respond directly to your question, I cannot type zero in line 4. I can get zero to appear in line four by typing zero in line 1, but then I lose the benefit of the Arizona deduction for the charitable contribution ($405 in my case).
It seems like there may be a flaw in the software I'm using?
