Hello again, I am embarrassed but at the same time glad to post that I've discovered that I made a data entry mistake, and the resulting Form 8606 error that I reported now seems to have been a kind of miscommunication between me and the TurboTax software. I know that sounds odd, but here's what I've seen/learned by looking back at TurboTax screens that I printed/saved this year as I was doing our tax return online. (Although documenting screens is labor intensive, it has been very helpful over the years, and this is a good example): I have a screen showing that I missed selecting the bullet that indicated my RMD was from my "inherited" IRA. However, the following two screens refer to "the original retirement plan owner" (when they were born and if they had taken any RMDs when alive). Surprising, right? This makes me feel a little better because it helps explain why I didn't immediately catch my mistake on the previous screen. Anyhow, I went back into the program, I clicked the bullet that says I inherited the IRA, and I completed the resulting screens for that 1099-R, and that solved my problem. Many thanks to all in the TurboTax community who kindly gave me their attention and assistance.
