Cal. Unemployment Insurance Code § 1178

(a) A claim for refund or credit may be filed with the director for any overpayment including, but not limited to, amounts paid subsequent to the filing for record of a certificate under Section 1703 or the entry of a judgment under Section 1815. (b) No refund shall be made or credit allowed unless a claim therefor is filed with the director within three years from the last day of the calendar month following the close of the calendar quarter for which the overpayment was made or within six months after assessments made under Article 8 (commencing with Section 1126) of this chapter become final or within 60 days from the date of overpayment, whichever period expires the later, but prior to the expiration of such periods even though no claim is filed the director on his own initiative shall make refunds pursuant to Section 1177 or may allow credits. (c) No refund of employer or worker contributions, penalties or interest shall be made or credit for worker contributions allowed unless the employing unit conforms, within one year after the allowance of credit or approval of the claim for refund, to authorized regulations with respect to the refund to workers entitled thereto of any money deducted by the employing unit under Section 984. (d) Following a final decision denying a petition for reassessment pursuant to Article 11 (commencing with Section 1221), the employing unit or other person which was a party to the petition may file a claim for refund upon payment of the amount of the assessment, including interest and penalties, and thereafter may pursue all administrative and judicial review rights accorded in Article 11 (commencing with Section 1221) and Article 12 (commencing with Section 1241). (e) No refund of employer contributions paid pursuant to Section 976.5 shall be made unless the payment is made by an employer described in subdivision (c) of Section 976.5, or the amount paid is less than or exceeds the amount needed to change the employer’s contribution rate. Refunds permitted under this subdivision shall be considered an undesignated payment and allocated according to subdivision (b) of Section 1110.1.