One last post for me dmertz (I hope). If I choose to make all $6,500 non deductible and answer the interview to indicate that $4,500 was contributed between January 1, 2017 and April 18, 2017 form 8606 populates line 4 with the $4,500 amount. However, regardless of whether I put zero or $4,500 on line 4 the result on line 14 (your total basis in traditional IRAs for 2016 and earlier yeas) shows $4,500. The IRA Information Worksheet gets its line 3 from line 14 of form 8606 and of course it shows $4,500, but the line is labeled "basis carryover as of 12/31/2016". But I had no balance in my traditional IRA on December 31st having converted the $2,000 to a Roth earlier in the year. So here are my question(s): 1) how can I have a 12/31/16 basis under this scenario? 2) How will this supposed basis affect my 2017 taxes, if at all? I know the contribution year is extended to the filing deadline while conversions are in what ever calendar year they're executed in, but what about basis in this case? And finally, if I contribute the remaining $4,500 to a non deductible IRA before the filing deadline can I immediately do a Roth conversion without it being taxable in 2017? I ask this given a potential basis entering tax year 2017.
