If you don't have a prior year return to find your previous year’s AGI, you have a few options.
Note: If you didn't file last year and you’re in TurboTax, just make sure to indicate that when asked. If you've already entered a number for your AGI, manually enter “0” instead.
Still having trouble? Call the IRS at 1-800-829-1040 between 7AM to 7PM local time, or make an appointment at a local IRS office.