If you filed with TurboTax you can obtain your 2018 AGI from last year's return. Please make sure you login to TurboTax Online with the exact same User ID and password you used last year.
1. Sign In to TurboTax in the correct account from last year.
2. Go to the prior year section in My Tax Timeline.
3. Click View adjusted gross income .
Also, you can request a tax transcript online from the IRS which is a free service and the transcript is typically available the same day.
Please see this TurboTax FAQ for more Information: https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/00/25947