Form 8606 part I basis

[Rhys]

My form 8606 shows an incorrect IRA basis in Part I line 14.  I have been doing backdoor Roth conversions for the last 10 yrs.  Every year is the same process.  I have never had, nor entered a previous year basis, since I have always completely converted my traditional IRA balance every year.  This year (2025 tax yr) my form 8606 shows a non zero number for the basis on line 14.  I have entered a zero basis in the q&a, so not sure where this number comes from.  I have re-entered the info from my 1099R, but still shows the incorrect basis.  Where does this number come from where I can change it to zero?

[baldietax]

what's happening on the rest of the 8606?  Does line 8 show your 1099-R conversion, Line 13 should show the nontaxable amount and Line 14 is the basis left over, it's a calculated field not something you would or should adjust.  If it's not zero that means something has not been entered or answered correctly across the 1099-R and IRA contribution sections so you should go back thru them.

https://ttlc.intuit.com/turbotax-support/en-us/help-article/retirement-benefits/enter-backdoor-roth-...

[DanaB27]

To clarify, was your value of all your traditional/SEP/SIMPLE IRAs $0 at the end of 2025? 

Another option, did you have a loss before you made the conversion? If yes, then it is possible to have a left over basis that is carried over to the future.