My business address / primary business location is California, but my incorporation is in Delaware. But I have not performed any services or anything in Delaware — only California.
In the Business Info section, I know it makes sense to put California in the "primarily doing business in" section. But should I be putting Delaware or nothing into "Also doing business in"? I don't know whether TurboTax is asking this because it's trying to figure out how many states I need to file in (in which case I'd put in both), or if it's actually asking where I have actively done my work (only California).
You should not list Delaware as a location where you are "Also doing business in". You do not need to file a Delaware business tax return. According to the Delaware Division of Revenue:
Delaware Corporations:
Who do NOT Conduct Business in Delaware are not required to file a Delaware Corporate Income Tax Return, regardless if incorporated under the laws of Delaware.
You should not list Delaware as a location where you are "Also doing business in". You do not need to file a Delaware business tax return. According to the Delaware Division of Revenue:
Delaware Corporations:
Who do NOT Conduct Business in Delaware are not required to file a Delaware Corporate Income Tax Return, regardless if incorporated under the laws of Delaware.