(1) The department shall classify all occupations or industries in accordance with their degree of hazard and fix therefor basic rates of premium which shall be:
(a) The lowest necessary to maintain actuarial solvency of the accident and medical aid funds in accordance with recognized insurance principles; and
(b) Designed to attempt to limit fluctuations in premium rates.
(2) The department shall formulate and adopt rules governing the method of premium calculation and collection and providing for a rating system consistent with recognized principles of workers' compensation insurance which shall be designed to stimulate and encourage accident prevention and to facilitate collection. The department may annually, or at such other times as it deems necessary to achieve the objectives under this section, readjust rates in accordance with the rating system to become effective on such dates as the department may designate.
(3)(a) After the first report is issued by the state auditor under RCW
51.44.115, the workers' compensation advisory committee shall review the report and, as the committee deems appropriate, may make recommendations to the department concerning:
(i) The level or levels of a contingency reserve that are appropriate to maintain actuarial solvency of the accident and medical aid funds, limit premium rate fluctuations, and account for economic conditions; and
(ii) When surplus funds exist in the trust funds, the circumstances under which the department should give premium dividends, or similar measures, or temporarily reduce rates below the rates fixed under subsection (1) of this section, including any recommendations regarding notifications that should be given before taking the action.
(b) Following subsequent reports issued by the state auditor under RCW
51.44.115, the workers' compensation advisory committee may, as it deems appropriate, update its recommendations to the department on the matters covered under (a) of this subsection.
(4) In providing a retrospective rating plan under RCW
51.18.010, the department may consider each individual retrospective rating group as a single employing entity for purposes of dividends or premium discounts.