1) Yes. The VBTA does not require the spouses to file a joint return in order to take advantage of its provisions.
2) That is correct. An active duty service member who is a non-resident of CA is exempt from CA income tax only on his/her military pay.
3) Pre-tax 401K contributions are exempt from CA state income tax.
4) Non-residents of CA are taxed only on CA-source income. Interest and dividends have a source in California if the account or security is used in a trade or business or pledged as security for a loan, the proceeds of which are used in a trade or business in California. Capital gains from the sale of stocks and bonds are sourced to the resident state of the taxpayer at the time of the sale. See "Income Taxable by California" on page 6 of the CA tax publication:
https://www.ftb.ca.gov/forms/2022/2022-1031-publication.pdf
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
