Maryland Code, Insurance § 27-217

(a) This section does not apply to:

(b) An authorized insurer or unauthorized insurer may not make available to a firm, corporation, or association of individuals through a rating plan or form, property insurance, casualty insurance, or surety insurance at a preferred rate or premium based on a fictitious group of the firm, corporation, or association of individuals.

(c) A form or plan of insurance that covers a group or combination of persons or risks may not be written or delivered in or outside the State to cover persons or risks in the State at a preferred rate or on a form other than the rate or form offered to the public generally, including persons not in the group or combination, unless the form, plan of insurance, and rates or premiums to be charged have been submitted to and approved by the Commissioner as:

(d) The Commissioner shall adopt regulations to carry out subsection (c) of this section as it applies to property insurance or casualty insurance on motor vehicles.