Not sure what makes you think you will go to jail. Your AGI is on line 11 of your federal Form 1040. Information flows from your federal return to the state return. The school district form will be part of the forms you can prepare when you prepare your state return.
For the Ohio School District income tax form SD 100, you start with the Ohio Adjusted Gross Income (AGI), not the federal AGI. The Ohio AGI is found on line 3 of the Ohio IT 1040. TurboTax (TT) automatically does that (put the IT1040 line 3 amount on line 1 of form SD100.
The Ohio AGI is the federal AGI plus Ohio Schedule A additions and minus Ohio Schedule A deductions.
I couldn't figure out how to get to my 1040. Was being told by Google I could review it at the end, but I couldn't get to the end to review it because of an incorrect agi in the sd100. Ended up going with Freetaxusa. Took ten minutes and was really simple, no problems, everything's already accepted. But yeah I was just freaking out about the jail thing, that wasn't really logical, I'll give ya that.