Whether to do a back door roth or just enter the 1099R

If you are working on a 2025 return, you would enter the 1099-R info just as indicated on the 1099-R Worksheet, and while still in that worksheet, scroll down to page 2, and lines B4 & B5 are your heroes.

You can’t just decide to do a back door Roth that is something your client has to want. Just enter the 1099R 

You stated “to her Roth IRA” but not where the funds came from.

Does your client have Basis (nondeducted, post-tax funds) in the origination account? If so, the transfer is not a transfer, it is a conversion. Conversions are pro rated taxable. All Trad IRA, SEP IRA, SIMPLE IRA and Rollover IRA are aggregated for purposes of Form 8606; the exclusion is inherited IRA.

Backdoor Roth IRA is when the “transfer” from the origination account includes that all those aggregated accounts don’t exist, have $0 FMV, or contain only Basis, which doesn’t make sense because there will be never-taxed growth and earnings. Backdoor = only post-tax funds exist, and the conversion from a pre-tax account type to a post-tax account type means there is no taxable event.

You can’t go by the 1099-R, if the taxpayer has a commingled account or those account types that need to be aggregated, because the issuer of the 1099-R only knows the conditions and situation which apply to their trustee position. They don’t know the taxpayer’s full situation.

You have to ask the taxpayer about other accounts and Basis. Maybe there is a Form 8606 in the prior year(s) tax files.