Did you all try using excess real estate taxes in form 8829. I used the full RE taxes in the first form 8829. Then in second form 8829 I put in 0 in the RE taxes, but added full amount in Excess RE taxes. The total deductions turn out to be the same with the excess RE taxes on form 8829.
Then I checked my Schedule A form where I entered the full RE taxes by overriding TT. Then I compared the Sch A from older file where I was getting error with the new file with Excess RE taxes on one of the form 8829. The numbers were exactly the same. I have to take standard deduction so it did not matter as Sch A will not be used. But for comparison it was exactly the same.
Then I compared CA Schedule CA for itemized deductions for California. Those numbers were exactly the same in my old file and the updated file.
So, for me the excess RE taxes works well. Now TT is also not giving any error. So I am going to file that way. Not sure if you have tried and found any difference. Most likely you will not need to do any manual calculations for Sch A if you use excess RE tax method.
Hope it works for you.
