Move from any state to California. This is what TurboTax does:
1. Creates Form 8829 Wks for the home office in another state. It has nothing to do with California!
2. Reports an error that the sum of the values in the Forms 8829 must be equal to the value in Sch C Wks. But TurboTax makes them different by itself when the tax adjustment because of the differences in the Federal and state laws is not equal to 0.
It's a mess! This app can't be trusted to file your taxes in California!
I think this can be fixed by updating field 6 in forms 8829 to the correct value from Schedule C, line 28. TurboTax corrupted that value by adding the adjustment amount to it. This is a clear issue in the app.
Also, I hate the fact that the app didn't explain the origin of the adjustment value. That's very, very bad that it works that way.
The problem is that TurboTax does NOT allow to change field 6 in forms 8829 to the correct value. That's absolutely wonderful to know in 2 hours before the deadline to file the taxes...
An alternative approach is to split the adjustment between the home offices. But it clearly says in the form that the correct value in line 6 must be from Schedule C, line 28 which means that it's the Federal Schedule C. So, the values there must be equal. But they are not, and TurboTax doesn't allow to make them equal (the field is read-only).