That's an interesting point. The total tax is roughly $4400, so if that were the case would the credit not be limited at $4400? I also tried putting the form on their partner's return as they bought the car in both of their names, although the clean vehicle seller report is in his name (they are an unmarried couple). The partner's total tax is over 30k and her limitation is still $4000. I feel like I must be missing something either with the software or the nature of the credit itself. I will paste a couple screenshots to illustrate what's happening. Was there a recent update with this form or something?