You wrote: "My 2018 taxes was not filed. My 2019 was rejected had no AGI from 2018 .Should I do my 2018 taxes 1st to get my AGI for 2019 taxes ?"
"Should I do my 2018 taxes 1st to get my AGI for 2019 taxes ?"
That won't help any with your AGI rejection problem. You would be filing the 2018 return too late for it to have an impact on this problem. Anyone who filed a 2018 return after mid-November 2019 would still have to show an AGI of 0 when efiling the 2019 return.
If you did not file a 2018 return, then when TurboTax asks for your 2018 AGI, you would enter a 2018 AGI of 0.
TurboTax may ask you if you filed a return for 2018. If you said "no", TurboTax may enter the AGI of 0 for you in the background. If it didn't, then you can enter the AGI of 0.
