Line 9, of form IT1040, comes from line 33 of the Ohio Schedule of Credits. Look there for details. The most common credits are:
-Exemption credit (line 9 of the schedule)
-Earned Income credit (line 13)
-Joint filing credit (line 12 )
-Retirement Income credit (line 2)
-Sr citizen credit (line 4)
-Day care credit (line 6)
