Maryland Code, Transportation § 13-909

(b)(1) During the registration period in which the system is initiated, vehicle registrations may be issued for periods varying from 7 months to 18 months with fees prorated according to the number of months for which the registration is issued.

(2) Vehicle registration plates or validation tabs shall be issued and displayed in accordance with a schedule established by the Administration.

(3) Any new registration or renewal issued during the year may be issued initially for other than a 12-month period to facilitate an equal volume of monthly issuances and the registration fee shall be prorated for the period issued.

(4) For the purpose of maintaining relatively uniform work loads, the Administration shall evaluate monthly volumes of registration renewals from time to time and any portion of a monthly issuance may be rescheduled by applying a different expiration date and prorating the fee accordingly.

(5) The Administration shall refund a registration fee on surrender of a registration card and unused registration plates by the owner as provided under § 13-938 of this subtitle only if the return is made prior to the expiration date of the registration period for which the application for refund is made.

(6) When the Administration assesses a prorated fee, it shall be calculated by multiplying one-twelfth of the applicable fee by the number of months for which the issuance or renewal is made and adjusting this amount to the nearest dollar amount.