If this was an inherited traditional IRA (code 4 with the IRA/SEP/SIMPLE box marked), you'll need to prepare Form 8606 Part I separately from TurboTax because TurboTax does not support the preparation of Forms 8606 for inherited traditional IRAs. For an inherited traditional IRA, TurboTax only asks you to enter the taxable result from the calculation on the Form 8606 that you've manually prepared. You'll need to mail your tax return and include the Form 8606.
