Where do I enter the prior-year AGI and PIN in a 1040 return?
The prior-year AGI and PIN may be entered on the PIN screen under the Form 2350/9465/56 Only section at the bottom of the screen.
Note: The prior-year AGI and PIN is only required under certain circumstances; for example, when filing Form 9465, Installment Agreement Request.
For more information about signing an electronic return see the IRS site Signing Your Return Electronically.