Cal. Rev. & Tax. Code § 10901

Whenever the department or the Department of Housing and Community Development erroneously collects any license fee or portion of a fee not required to be paid under this part, or erroneously applies any offset provided under this part, the erroneously collected amount shall be refunded to the person paying it upon application therefor made within three years after the date of the payment. If the department or the Department of Housing and Community Development discovers an error, it may make a refund in the absence of an application therefor.