Cal. PRC § 3430

Any person claiming and protesting that the assessment made or charges assessed against him are void, in whole or in part, may bring an action against the State Treasurer for the recovery of the whole or any part of the charges, penalties, or costs paid on such assessment, upon the grounds stated in his protest. No action may be brought later than the third Monday in February next following the day upon which the charges were due, and unless the person has filed with the State Controller, at the time of payment of the charges, a written protest stating whether the whole assessment or charge is claimed to be void, or if a part only, what part, and the grounds upon which the claim is founded. When so paid under protest the payment shall not be regarded as voluntary.