I received the same letter the other day, I called them, told them i was only based there for 5 months and never lived there. (Not even a crashpad)
They told me to fill out section B on the form and fax or mail it back to them. I filled it out and told them that less than 50% of my income was made while working out of CA and thats all i was told to do. We'll see if i hear anything back from them or not but this was from 2007 taxes!! 2 years later they are attempting to hit me up for taxes because they're going bankrupt. Not my problem California