Regarding your federal income taxes -
You will need to include your single member LLC on your individual tax return as a disregard entity (regardless of where the LLC is registered).
Depending on the type of business activities will determine where to report the LLC income and expenses on your individual tax return (if a business LLC - Schedule C, if a rental property LLC - Schedule E)
For more information
see Single
Member Limited Liability Companies
Regarding your state taxes -
If you live and operate your business in California, you will be subject to CA tax regardless if you incorporate in Delaware. A Delaware corporation that operates in CA, must register as a foreign corporation with the State of California and pay California income and franchise tax. You will report the LLC income and expenses on your individual CA resident state income tax return (as a disregarded entity).
You may also owe franchise tax to Delaware since the LLC is registered in DE. You will be able to claim these DE state franchise taxes as part of your LLC's business licenses and taxes expense on your Schedule C (or Schedule E). However, if no DE source income is generated by this LLC, you will not have an DE nonresident state income tax filing.
