A form 8606 must be filed for each tax year required ... this form can be filed on it's own without a tax return since it is a "stand alone" form.  https://www.irs.gov/forms-pubs/prior-year

Thank you for the information.  Can I submit all of my amended 8606s for the previous years in one mailing to the IRS with the explanation?

Yes if you make absolutely sure that the cover letter explicitly says there are more than one tax year involved.

---

@rg69morrison wrote:

  Since I've reported all my contributions each year,

 

---

Your post is not clear.  *How* did you report your non-deductible Traditional IRA contributions each year?

 The ONLY way to report a non-deductible contribution is on a 8606 form that TurboTax generates automatically when you enter the non-deductible contribution.

If you reported the contribution are you sure that is was not deducted?

---

@Critter wrote:

Yes if you make absolutely sure that the cover letter explicitly says there are more than one tax year involved.

---

Note that there is a $50 penalty for each 8606 form that is filed late unless you also state a reasonable explanation and request a waiver of the penalty.

My non-deductible contributions were reported each year on 8606, line 1 that Turbo Tax generates.  My previous years basis was not reported on the 8606.  Line 2 was not completed.

Hope that helps clarify.

Line 3 should have the sum of line 1 & 2.   If there was no Traditional IRA distribution  for the year then line 14 should be the same as line 3.    The next years 8606 line 2 would come form the last 8606 filed, line 14.

If you use TurboTax each year and transfer the last years tax return then TurboTax should keep track of the prior basis in the "IRA information worksheet" line 12 unless you skipped a year or did not transfer.

There would not be a penalty since you did file a 8606-  Amending a 8606 does not produce a penalty.