379.888.  Definitions for sections 379.888 to 379.893 — notice to insured, when — department to notify insurers. — 1.  As used in sections 379.888 to 379.893, the following terms mean:

  (1)  "'A' rated risk", any insurance coverage for which rates are individually determined based upon judgment because neither a rate service organization nor the insurer has yet established a manual rate based upon experience, except that if a rate service organization or the insurer acquires sufficient experience to establish, or if the insurer itself has, a manual rate for such coverage, then such coverage shall no longer be considered an "A" rated risk for each insurer;

  (2)  "Base rate", the rate designed to reflect the average aggregate experience of a particular market, prior to adjustment for individual risk characteristics resulting from application of any rating plan;

  (3)  "Classification", a grouping of insurance risks according to a classification system used by an insurer;

  (4)  "Classification system", a schedule of classifications and a rule or set of rules used by an insurer for determining the classification applicable to an insured;

  (5)  "Commercial casualty insurance", casualty insurance for business or nonprofit interests which is not for personal, family, or household purposes;

  (6)  "Director", the director of the department of commerce and insurance;

  (7)  "Rate", a monetary amount applied to the units of exposure basis assigned to a classification and used by an insurer to determine the premium for an insured;

  (8)  "Rating plan", a rule or set of rules used by an insurer to calculate premium for an insured, and the parameter values used in such calculation, after application of classification premium rates to units of exposure; and

  (9)  "Rating system", a collection of rating plans to be used by an insurer, rules for determining which rating plans are applicable to an insured, a classification system, and other rules used by an insurer for determining contractual consideration for insured.

  2.  Nothing in this section applies to premium increases or decreases from:

  (1)  Change in hazard of the insured's operation;

  (2)  Change in magnitude of the exposure basis for the insured, including, without limitation, changes in payroll or sales;

  (3)  "A" rated risks.

  3.  Any renewal notice of a commercial casualty insurance policy as defined in section 379.882 for any Missouri risk or portion thereof which would have the effect of increasing the premium charged to the insured due to a change in any scheduled rating factor applied to the policy during the previous policy period shall contain or be accompanied by a notice to the insured informing the insured that any inquiry by the insured concerning the change may be directed to the agent of record or directly to the insurer.  When any insured makes a request for information pursuant to this subsection, the insurer, directly or through the insurer's agent, shall inform the insured in writing in terms sufficiently clear and specific of the basis for any reduction in a scheduled rating credit or increase in a scheduled rating debit which is applied to the policy.  Evidence supporting the basis for any scheduled rating credit or debit shall be retained by the insurer for the policy term plus two calendar years pursuant to section 374.205.  The department of commerce and insurance shall notify commercial casualty insurers of the requirements of this section by bulletin.

  4.  Any renewal involving a "premium alteration requiring notification" as defined in subsection 6 of section 379.321, shall be handled pursuant to the requirements of that subsection.