(a) Due consideration shall be given to past and prospective loss experience within and outside this Commonwealth, to physical hazards, to safety and loss prevention factors, to underwriting practice and judgment to the extent appropriate, to catastrophe hazards, if any, to a reasonable margin for underwriting profit and contingencies, to dividends, savings or unabsorbed premium deposits allowed or returned by insurers to their policyholders, members or subscribers, to past and prospective expenses both country wide and those specially applicable to this Commonwealth, and to all other relevant factors within and outside this Commonwealth.

(b) The systems of expense provisions included in the rates for use by any insurer or group of insurers may differ from those of other insurers or groups of insurers to reflect the requirements of the operating methods of any such insurer or group with respect to any kind of insurance, or with respect to any subdivision or combination thereof for which subdivision or combination separate expense provisions are applicable.

(c) Risks may be grouped by classifications for the establishment of rates and minimum premiums. Classification rates may be modified to produce rates for individual risks in accordance with rating plans which establish standards for measuring variations in hazards or expense provisions, or both. Such standards may measure any differences among risks that can be demonstrated to have a probable effect upon losses or expenses.

(d) Rates shall not be excessive, inadequate or unfairly discriminatory. No rate shall be held to be unfairly discriminatory unless, allowing for practical limitations, it clearly fails to reflect with reasonable accuracy the differences in expected losses and expenses. A rate is not unfairly discriminatory because different premiums result for policyholders with like-loss exposures but different expense factors, so long as the rate reflects the differences with reasonable accuracy. A rate is not unfairly discriminatory if it is averaged broadly among persons insured under a group, franchise or blanket policy.

(e) This section shall not be construed to prohibit rates for automobile insurance which are based, in whole or in part, on factors, including, but not limited to, sex, if the use of such a factor is supported by sound actuarial principles or is related to actual or reasonably anticipated experience; however, such factors shall not include race, religion or national origin.