You do not have to file an Ohio income tax return if your Ohio adjusted gross income (line 3) is less than or equal to $0.
However, even if you meet the exception above, if you have a school district income tax liability (SD 100, line 2), you are required to file the Ohio IT 1040.
NOTE: If your federal adjusted gross income is greater than $28,450, the Department of Taxation recommends that you file an Ohio IT 1040 or IT 10, even if you do not owe any tax, to avoid delinquency billings.