Thing is, although TT shouldn't be adding the two average balances together, that's what it does. It's not a critical issue for Federal, since the user does the limit calculation outside TT (update 2/5: the Federal worksheet, which one gets by QuickZoom but not automatically, now can be persuaded to calculate the prorated average and limited interest deduction correctly, but that doesn't carry over to the corresponding California line), but for California TT does the calculation itself in a worksheet that feeds the (not yet final) Schedule CA, and TT does the calculation wrong. That needs to be corrected by Intuit.
