The department shall give a notice of the filing of a new or additional claim to the employing unit by which the claimant was last employed immediately preceding the filing of the 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 that may affect the claimant’s eligibility for benefits, including, but not limited to, facts pertaining to eligibility under Section 1256. The 10-day period may be extended for good cause. If after the 10-day period the employing unit acquires knowledge of facts that may affect the eligibility of the claimant and facts could not reasonably have been known within the period, the employing unit shall, within 10 days of acquiring the knowledge, submit the facts to the department, and the 10-day period may also be extended for good cause.