Wash. Rev. Code § 51.44.110
Disbursement out of the several funds shall be made only upon warrants or payments drawn by the department. The state treasurer shall pay every warrant or payment out of the fund upon which it is drawn. If, at any time, there shall not be sufficient money in the fund on which any such warrant or payment is drawn wherewith to pay the same, the employer on account of whose worker it was that the warrant or payment was drawn shall pay the same, and he or she shall be credited upon his or her next following contribution to such fund the amount so paid with interest thereon at the legal rate from the date of such payment to the date such next following contribution became payable and, if the amount of the credit shall exceed the amount of the contribution, he or she shall have a warrant or payment upon the same fund for the excess and, if any such warrant or payment shall not be so paid, it shall remain, nevertheless, payable out of the fund.
RCW 51.44.110