My father died in 2020. He had several traditional IRA accounts with a significant tax basis. He last took an rmd in 2019 and filed 8606 forms in 2019 and preceding years showing the basis. There was no rmd in 2020, so there is no 8606 form with his 2020 taxes. My sister and I inherited these IRA accounts 50/50 and started taking distributions in 2021. We'll be taking everything out over a 10 year period. I had forgotten there was a basis and treated the distributions as 100% taxable for 2021 and following for my own taxes so far.
Can I still claim the basis going forward, since there are 8606 forms filed with my father's taxes showing the basis amount? I assume the basis is still the same as at time of death (50% of the total basis for me) since I am unable to make any further contributions to his IRA. Could I go back and file amended forms for several of the past few years to claim the basis? I believe the limit is three years, so would 2023 be the earliest that qualifies? In any case it seems I should be able to claim the basis going forward.
Any information would be appreciated.
