Cal. Unemployment Insurance Code § 4654

The department shall give a notice of the filing of an application or an additional claim to the employing unit by which the individual was last employed immediately preceding the filing of the application or claim unless the additional claim is the result of the filing of a partial claim as defined by the department, there has not been a subsequent employing unit which is designated as the last employer, and there is no separation issue. The employing unit so notified shall submit within 10 days after the mailing of the notice any facts then known which may affect the individual’s eligibility for federal-state extended benefits. The 10-day period may be extended for good cause. If after the 10-day period the employing unit acquires knowledge of facts which may affect the eligibility of the individual and those facts could not reasonably have been known within the period, the employing unit shall within 10 days of acquiring that knowledge submit those facts to the department, and the 10-day period may also be extended for good cause.