"So I understand that I pick a domicile state, and because my deferred income arrives every month while I am in both states, then, I will be a part time resident in the non domicile stake?"
No. In tax terminology, there is no such thing as a "part time" resident. You are either a resident, a non-resident, or a part-year resident.
A part-year resident is someone who literally moves his domicile - his main, primary, permanent home - from one state to another during the tax year.
A non-resident is someone whose domicile does not change during the year, but who has a tax-filing obligation in a non-domicile state.
Here are CA's criteria for determining which state is your domicile state:
• Amount of time you spend in California versus amount of time you spend outside California.
• Location of your spouse/RDP and children.
• Location of your principal residence.
• State that issued your driver’s license.
• State where your vehicles are registered.
• State where you maintain your professional licenses.
• State where you are registered to vote.
• Location of the banks where you maintain accounts.
• The origination point of your financial transactions.
• Location of your medical professionals and other healthcare providers (doctors, dentists etc.), accountants, and attorneys.
https://www.ftb.ca.gov/forms/2020/2020-1031-publication.pdf
The importance of all this is that your state of domicile can tax ALL your income, regardless of its source. Other states can only tax income that is "sourced" within that state.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
