(1) The commissioner shall prescribe regulations for the establishment, maintenance, and dissolution of joint accounts by two or more employers, and shall, in accordance with such regulations and upon application by two or more employers to establish such account, or to merge their several individual accounts in a joint account, maintain such joint account as if it constituted a single employer's account.
(2) Joint accounts may not be established for professional employer organizations, as defined in RCW 50.04.298, or third-party payers, as defined in RCW 50.04.248, and their clients.