@lchan wrote:
Looking back at my returns, I have several years where the value in Line 2 is $0, therefore the cumulative value is never reported correctly.
Most recently, in 2022, Line 2 is $0, thus restarting the total.
How far back can I submit an amendment, because it's several thousand dollars that are being miscalculated?
I would go back as far as you can prove. The IRS will not pay a refund on an amended return more than 3 years old, but I think they will accept your form 8606 since you are just documenting the carry over basis you missed.
You would need to download the specific form 8606 for each year. The IRS has prior year forms on their web site. You also need form 1040-X for each year that you need to amend. Since you are not changing your deduction (you already did not take the deduction, you just didn't carry over the prior deductions correctly), you will need to copy the specific numbers from your tax returns to the 1040-X, but there's no math involved. Column A would be what you originally reported, column B (changes) is zero, and column C is the same as column A. The reason you would write on part II would be to correct form 8606 because you failed to include the prior basis on line 2.
https://www.irs.gov/forms-pubs/about-form-1040x
You will have to go in order, starting as far back as you have records to prove what you did. If you don't have copies, the IRS is supposed to have your transcripts for either 7 or 10 years.
https://www.irs.gov/individuals/get-transcript
Start with the first form 8606 you can prove is wrong, then prepare them in order. Prepare a 1040-x to accompany each form 8606. Sign everything, and mail to the IRS (separate envelopes for each year). Then keep the final amended form 8606 from 2023 with your records to use when you make future contributions or withdrawals.
