(a) Except to the extent there is a redetermination under AS 23.20.330 — 23.20.405, all final determinations and decisions are conclusive upon employing units with notice, the department, and the claimant. A final determination or decision as to benefit rights is not subject to collateral attack by an employing unit regardless of notice.
(b) The department, or appeal tribunal, shall reopen a determination or decision or revoke permission for withdrawal of an appeal if (1) it finds that a worker or employer has been defrauded or coerced in connection with the determination, decision, or withdrawal of the appeal, and (2) the defrauded or coerced person informs the appropriate officer or body of the fraud or coercion within 60 days after the person has become aware of the fraud or within 60 days after the coercion has been removed.