Cal. Unemp. Ins. Code § 1177
Except as provided by subdivision (b) of Section 1178, if the director determines that any amount of contributions, penalty or interest has been erroneously or illegally collected he shall set forth on the records of the department the amount collected in excess of the amount legally due and the name of the employing unit or other person by whom it was paid and shall refund the amount to the employing unit or other person by whom it was paid if the amount does not include refundable worker contributions. If refundable worker contributions are involved and a claim has not already been filed the director shall give notice to such employing unit or other person of such amount. The excess amount shall be credited on any amounts then due from or accrued against the employing unit and the balance shall be refunded to the employing unit or its successor, administrators or executors.
Ca. Unemp. Ins. Code § 1177