The TurboTax desktop calculations for Form 8606-T do not appear to be working correctly for a distribution from an IRA with previous nondeductible contributions.

It worked for me this year.

 

I would suggest checking:

 

the "IRA Information Worksheet" to make sure your basis carryforward is present as well as other information (such as line 18 12/31/23 values of traditional IRAs and rollovers).

 

Also make sure the interview questions re: the conversion were right by checking the 1099-R distribution details (lines B1-B8).

 

not sure where in the interview these questions are asked but you can see the results in the forms.

 

 

 

 

Thanks for your comment.  Turned out I hadn't put a check n the little box in cell 7 of the 1099R that said IRA/SEP/SIMPLE.  That fixed it.

These things are easy to miss. The whole system is so complicated. Sometimes TT is at fault, but sometimes we all just miss a subtlety.