Cal. Bus. & Prof. Code § 5499.14

The legislative body of the city or county may order a refund of all or part of an assessment pursuant to this chapter if it finds that all or part of the assessment has been erroneously levied. An assessment, or part thereof, shall not be refunded unless a claim is filed with the clerk of the legislative body on or before November 1 after the assessment became due and payable. The claim shall be verified by the person who paid the assessment or by the person’s guardian, conservator, executor, or administrator.