You may be in a situation of dual residency, which would require you file as a resident in each of the two states. You can determine that by reviewing each state's legal definition of "resident".
Oregon's definition is described in Section (1) of this Oregon statute:
https://oregon.public.law/statutes/ors_316.027
An Oregon resident is taxed by Oregon on all their income, regardless of its source.
California's definition of "resident" is contained in this CA tax publication. In particular, see Section G on page 5:
https://www.ftb.ca.gov/forms/2023/2023-1031-publication.pdf
A California resident is taxed by California on all their income, regardless of source.
If you do have to file in both states, then you would be able to claim a credit on your OR return for the taxes paid to CA on the income taxed by both states. The credit prevents double taxation, which is prohibited by federal law.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
