I have inherited pre-1987 IRAs with non-deductible contributions that have tracked basis in form 8606 from previous years, being entered into Turbotax desktop for the first time. There does not appear to be a way to manually enter information into form 8606, as the fields needed are blued out, startin with Line 4/5. Line 4 takes me to the Traditional IRA Smart Basis worksheet, I enter the information there, and in the "traditional IRA year-end value detail". It lets me fill out Part 1 Line 1,2,3. Eventually, it lets me select the 1099-R in question. However the taxable amount, Box 2a, is what I need to use form 8606 to calculate! If I scroll down on the 1099-R, I see the "Traditional IRA Basis and Value Smart worksheett"..but that then takes me back to the "IRA Information worksheet". There never seems to be a way to enter line 4 (value 0) 6,7, and 8 which are needed to calculate the rest.
