What's my 2017 AGI if someone claimed me as a dependent?
It all depends on whether or not you filed a return for yourself in 2017.
If you didn't file your own return last year and you’re in TurboTax, just tell us you didn’t file last year when we ask you. But if you already entered a number, be sure to change it to 0.
Otherwise, if you did file your own return in 2017 but someone claimed you as a dependent (this often happens with college-age students), use the AGI from your 2017 return, not theirs.