Section 4673 - Exceptions(a) No rate increase may be applied for a claim payment under uninsured motorist, medical payment, comprehensive, fire, theft, or a combined additional coverage.(b) This subchapter shall not apply to an automobile that is:(2) used in the business of driver training; or(3) insured under a commercial plan.(c) No surcharge may be applied to a policy written for a term in excess of 12 months unless that policy provides for an annual adjustment of premiums.(d) The Commissioner may by rule designate mitigating circumstances, the existence of any of which shall remove the basis for application of a surcharge.(e) If a policy is surcharged as the result of an accident and subsequently the circumstances of the accident are found to include a mitigating circumstance, the insurer shall refund to the insured the increased portion of the premium generated by the accident.Added 1975, No. 75; amended 1979, No. 28, § 7.