“The best place to get this
number is from your originally-filed
2016 federal tax return. Even if you
amended it later, you must use the AGI from the 2016 return you originally
filed, even if it's way off.”
Use the AGI from the original
return. If you have a copy of last
year's original return, you can find your AGI here (depending on which form you
filed):
Form 1040 – Line 37
Form 1040A – Line 21
Form 1040EZ – Line 4
Form 1040NR – Line 36
Form 1040X – Line 1, Column A
Please read this TurboTax FAQ for more information about finding last year's AGI: https://ttlc.intuit.com/replies/3301618
