Enter your DFAS Form 1099-R in the IRA, 401(k), Pension Plans (1099-R) interview under Federal Taxers > Wages and Income > Retirement Plans & Social Security.
If you didn't get a DFAS Form 1099-R, go to the myPay website (https://mypay.dfas.mil).
The only way the program will ask you to complete a Substitute 1099-R is if you tell it you need to prepare one. See the attached screenshot example.
If you inadvertently started a Substitute 1099-R, use the "Delete a Form" tool to
remove the form.
See: How do I delete forms in TurboTax Online?
After deleting the substitute 1099-R, log out of the
program. When you log back in, use the Delete a Form tool to confirm
the substitute 1099-R has been removed from the list of forms in your
return.
