If you properly entered the 1099-R and said yes to the question that asks if you made nondeductible contributions and then entered the last filed 8606 line 14 carry-forward basis, and then entered the total 2017 year end value of all Traditional, SEP and SIMPLE IRA accounts that existed, then that will be applied to prorate the total basis between the distribution and 2017 year end value on a new 8606 form on lines 6-15.
(Note that those questions come by entering "continue" after the 1099-R summary screen.)
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
