I forgot to include the "non-deductible IRA" contributions for tax year 2015 and 2016 on my 2015 and 2016 tax returns. I mailed the corrected 8606 forms to IRS last year to reflect the correct contributions. However, IRS just sent me a letter asking me to submit 1040X for those two years. Honestly, I don't understand why I have to filll out the 1040x forms. As the non-dedutible IRS contribution does not show on 1040x at all.
