Amending prior incorrect backdoor before filing this year's return

[x555v]

Hi,

Background: I did my first Traditional IRA to Roth IRA conversion (backdoor) in 2021. No IRA account before that. Always kept $0 in the Traditional IRA, expect for short periods between contribution and conversion. Did not touch the IRA accounts in 2022. Did a 2nd backdoor in 2023 ($6500).

Problem: It appears I didn't enter the first backdoor correctly in the 2021 return. (I didn't find good TurboTax documentation on how to enter this at that time.) Form 8606 exists and only has Part II filled in (16: $6000, 18: $6000). But 1040 line 4b is $6000 instead of $0. I guess this means I paid more tax that I should have.

Question: Is it important to amend the 2021 return BEFORE filling 2023? If I understand correctly, there is historical information carried from past 8606 forms (basis?). To put it another way, if I don't amend 2021, will 2023 and potentially future returns keep being affected?

(Note that I will likely amend 2021 to recover the extra tax I paid. My question here is just a matter of timing.)

Thanks!

[DanaB27 · Accepted solution]

No, you don't need to file the 2021 amened return before e-filing 2023. It will not affect your 2023 return because you contributed and converted the funds in 2021, unless the converted amount was less then the contributed amount, then you would have a basis on line 14 of the 2021 Form 8606 to carry over to 2023.

Please see How do I amend my federal tax return for a prior year?