Md. Code, Environment § 2–611

(a) A person is not subject to action for a violation of this title or any rule or regulation adopted under this title so long as the person acts in accordance with a plan for compliance that:

(1) The person has submitted to the Secretary; and

(2) The Secretary has approved, with or without amendments, on the recommendation of the Air Management Administration.

(b) The Secretary shall act on any plan for compliance within 90 days after the plan for compliance is submitted to the Secretary.