You are not really adding it to your 2019 Form 1040, but you do need to enter your 2018 AGI into the software so that you can e-file 2019. The 2018 AGI is what the IRS uses to match up your 2018 return with the person who used that SSN last year with the person using the same SSN for 2019. It verifies your identity to the IRS.
https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/01/25947
Your 2018 tax return shows your 2018 Adjusted Gross Income (AGI) If you filed a joint return then the AGI is the same for each of you.
Form 1040 line 7
If you are using the same TT account that you used last year, you should also be able to find this number in your Tax Home for 2018
If entering the amount from your 2018 tax return does not work, then try entering “0” instead. If that does not work and you still cannot e-file, then print, sign, and mail your tax return.
You can get a free transcript of your past return from the IRS:
https://www.irs.gov/individuals/get-transcript
Note: If you filed late or amended your return, your correct 2018 AGI may not be in the system.
The IRS requires your 2018 AGI to verify your identity for e-filing. You will be prompted to enter your AGI before filing.
If you're paper-filing your return, you won't need your AGI because those are manually processed.
There are a few places you can get your 2018 AGI:
If you didn't file a 2018 federal tax return (or you haven't filed one yet), enter 0 as your AGI.
Married Filing Separately in 2018 but filing jointly in 2019?
Filed jointly in 2018 but are Married Filing Separately in 2019?
Please give me step by step instructions how I can add this number to the software. I have the AGI number and have been trying to do this for three hours.
Twice I have waited for a "help expert" to call me and once they hung up and the second time they wanted me to spend and additional $60 (after waiting 16 minutes)
All I want to do is insert this number in its proper space.
Thanks very much.
Go to File (not the one on the upper left if you have the CD/download software, but the one to the right of Review - unfortunately, the screens are laid out differently between different versions of the product). In any case, make like you are trying to file the return.
Proceed through the screens. If you have a refund, there will be a screen that asks if you want a direct deposit.
On the screen AFTER this, TurboTax will ask you to "sign" the return. You do this by entering last year's AGI.
The screen looks something like this:
The 22842 was the AGI from a 2018 test return (use your AGI instead) - this is under the taxpayers' names (covered by the blank boxes).
Let's put it this way, you should not be able to go all the way through the filing process without seeing this screen, if you are e-filing.