Can I sue a business owner personally in California?

Usually the corporation or LLC alone is liable for its obligations (members and shareholders are shielded (Corporations Code section 17703.04)), but owners answer personally on a signed guaranty, for their own torts or fraud, and under the alter ego doctrine when the entity is a shell used to work an injustice.

The default is separation: a corporation or LLC is its own legal person, and its debts are not its owners' (for LLCs, Corporations Code section 17703.04). Three routes pierce that separation. First, a personal guaranty: landlords and lenders routinely require one, and it makes the owner a direct contract party. Second, personal conduct: an owner who commits fraud or another tort is liable for it regardless of the entity, because incorporation shields status, not conduct. Third, alter ego: courts disregard the entity when there is such unity of interest that separateness has ceased (commingled funds, undercapitalization, the entity as a mere conduit for personal dealings), and honoring the form would sanction a fraud or promote injustice. Section 17703.04(b) applies the doctrine to LLCs, though failure to hold member meetings is not itself a factor. Alter ego can be pleaded in the case or raised after judgment, where courts may amend a judgment to add the controlling individual as a debtor.

Authority: Cal. Corp. Code § 17703.04