California taxes nonresidents on any income earned from California sources. Sourced income includes, but is not limited to:
- Services performed in California
- Rent from real property located in California
- The sale or transfer of real California property
- Income from a California business, trade or profession
Therefore, if you "occasionally work in CA," then any income you earned while physically present in CA is subject to CA income tax. You can claim a credit for tax paid to CA by filing an amended Utah income tax return.
Part-year resident and nonresident