No taxes. But if you're a Delaware Corp. there is a minimum Delaware franchise tax that's owed ~$400. Even when you have made transactions/sales, unless you make a profit you don't owe taxes. But once you have transactions (but still no profit which means still no tax) it would be prudent to get a pro to file your taxes - the filing process itself would be 500-2000 for the CPA firm.
In California, the California franchise tax is minimum of $800. But if you are a Delaware business, you may have to register as a foreign entity in California and have to pay $800 minimum.
If you have an office in San Francisco, you may have to register your business in San Francisco and there is a business tax per year also of a few hundred dollars. Usually Pro accountants don’t prepare pay your various state franchise or business registration taxes. But you still have to pay a pro to prepare your income tax if you most likely pay nothing and have no income.
This is not a legal advice but you have to pay taxes in every state where you have an office or a paid employee.