Maryland Code, Insurance § 11-310

(a)(1) The Commissioner may adopt a rule that requires that subsequent changes in the rates or supplementary rate information for a kind or line of insurance, subdivision of a kind or line of insurance, or rating class or rating territory be filed with the Commissioner at least 30 working days before they become effective if the Commissioner finds that with respect to that kind, line, subdivision, rating class, or rating territory:

(2) By written notice to the filer during the initial 30-day waiting period, the Commissioner may extend the waiting period for an additional period not exceeding 30 working days.

(b)(1) A rule adopted under this section may not remain in effect for more than 1 year after it is adopted.

(2) The Commissioner may renew a rule adopted under this section after a hearing and appropriate findings under this section.