I know it's possible to make a one-time rollover from an IRA to an HSA (i.e., up to the amount allowed by the HSA).
It's possible I already did this about 10 years ago. The paperwork I have on hand is insufficient to determine this for sure. Specifically, I have (a) only a slimmed-down tax history, (b) a monthly statement and a 5498 from the HSA trustee that contradict each other, and (c) no records from bank accounts.
Further, I no longer bank with the original IRA trustee, and the HSA trustee (who I do still bank with) insists their records do not go back that far.
Consequently, the final authority will be the IRS records.
So what--in addition to my 1040 and 5498 history--do I need to request? For example, is there a "receipts" history between my IRA trustee and HSA trustee that the IRS keeps and can provide me?