Thank you all so very much. It sounds like the right thing to do is to include not a check with the late 8606, but rather a letter. If I may, does the below text sound good? This would be for the letter enclosed with the 2017 8606:
I request a penalty waiver because I used ordinary prudence by relying on guidance from a credentialed advisor who turned out to be incorrect on this one matter.
This has just become clear to me, and I now take immediate corrective action. I do this in three ways. First, I file this 2017 8606. Second, separately I am filing a 2018 8606 for a nondeductible IRA contribution made in that year. Third, I will include a 2019 8606 with my 2019 Form 1040 to report a nondeductible IRA contribution in that year.
Thank you all again, most sincerely.
