Here are California's rules for filing Single:
You are single if any of the following was true on December 31, 2021:
- You were not married or an RDP.
- You were divorced under a final decree of divorce, legally separated under a final decree of legal separation, or terminated your registered domestic partnership.
- You were widowed before January 1, 2021, and did not remarry or enter into another registered domestic partnership in 2021.
https://www.ftb.ca.gov/forms/2021/2021-540-booklet.html
So, if you are still in your RDP, the answer to your question is NO, you cannot file your California tax return(s) as Single.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
