According to the California Franchise Tax Board, my turbotax generated California itemized deduction is off by about 14%, meaning I now owe additional taxes and penalties. Unfortunately, when I contacted FTB, they couuld not provide any meaningful insight as to why the calculations were so far off. Their only suggestions was to hire a CPA to understand the problem -- not that this would reduce the taxes, but that they would explain the discrepancy. I don't think going over the numbers myself would make any difference as I've already double and triple checked the numbers and going over them yet another time won't fix anything unless I know what I did wrong in the first place. My normal process is to enter everything in the federal forms and do several verification passes. Then for California, I just go with default for everything as I don't have anything beyond normal 1099-INT, DIV, B and the occasional K-1.
So my question is: what are things that are different between CA and Fed that TurboTax might not know about or that I might have gotten wrong? This is the first time I've had this problem. Should I just hire a CPA next year? The discrepancy is resulting in additional taxes and penalty in the amount of over $3k.