The Forms 5498 are both for 2021 which are for a personal IRA. I am not sure why the contributions were accounted for this way. What you are asking is what confused me when filing. I think you thinking about if I had contributions made that would be included up to about when taxes are filed.
My contributions are after tax from my savings account at my bank. The 2 forms I have are both dated for 2021 and add up to what my monthly contributions are. I just logged into my Turbo Tax account, and it says amended returns are just for adding additional forms. Looking closer at note with the 1st form 5498 I see the custodianship changed after the first week in September. That is why I have 2 forms for contributions.
So, I guess if this sounds correct, I just need to amend the return with the form 5498 I omitted.
