PEJ, you understand the instructions and Form 8606 correctly.  Rolling your 401(k) over to your traditional IRA has decreased the proportion of your nondeductible traditional IRA contributions to the overall value of your traditional IRAs, resulting in a decrease in the nontaxable proportion of your RMD and more of your basis remaining in your traditional IRA(s) to be applied to future distributions.  This result is dictated by law. ... View more

However, TurboTax does not always operate properly as I found out a year ago when my wife had to take her first RMD.   Her carry forward basis was zero in TurboTax but my basis was fine.   I traced that back to 2012 where the IRA Info worksheet showed the correct carry forward basis for both my IRA and my wife's IRA, but when transferred to 2013, my IRA basis was correct, but my wife's basis was zero, so zero carried forward after then.   Why my basis transferred, but my wife's did not, I have no idea (and no, I have not tried to reproduce it since those tax years are long gone so it would be useless to report a bug in 2012 or 2013).     But losing basis can happen, even if you transfer every year since it happened to me and it is not obvious that the IRA info worksheet is incorrect if no IRA distribution was taken. ... View more