Washington Revised Code Title 51. Industrial Insurance § 51.18.010. Availability--Rules--Coverage period

(1) The department shall offer a retrospective rating plan to insure the workers' compensation obligations of employers and groups of employers. The plan is to be made available to any employer or group of employers who:

(2) The retrospective rating plan shall be consistent with recognized insurance principles and shall be administered according to rules adopted by the department. Rules adopted under this section shall encourage broad participation by qualified employers and sponsors of retrospective rating groups.

(3) Each retrospective rating group approved by the department under this chapter shall select a coverage period and may be renewed at the end of each coverage period. For the purposes of this section, “coverage period” means a twelve-month period provided by the department by rule.