Maryland Code, Public Utilities § 4-204

(a)(1) The Commission may suspend, effective immediately and without formal proceedings, any new rate or change in rate proposed by a public service company.

(2) Unless suspended by the Commission, and subject to § 4-203 of this subtitle, a new rate or change in rate proposed by a public service company takes effect on the date specified in the rate application.

(3) The Commission shall furnish to the public service company proposing a rate a written statement of the reasons for the suspension.

(b)(1) The Commission promptly shall institute proceedings to consider whether the suspended rate is a just and reasonable rate.

(2) The Commission may:

(3) Subject to subsection (c) of this section, after the suspension or extension under paragraph (2) of this subsection expires, if the Commission has not entered a final order, the new rate or change in rate proposed by the public service company takes effect.

(c)(1) If a proposed new rate or rate increase takes effect before the Commission enters a final order in the proceedings, if practicable, the Commission may order the public service company that proposes the rate to keep a detailed and accurate account of:

(2) After the proceedings conclude, the Commission may require the public service company to refund with interest, to each person listed under paragraph (1)(ii) of this subsection, the part of the new rate or rate increase that the Commission finds unjustified.

(3) If a refund is not practicable, the public service company shall charge off and amortize the difference between the operating revenues under the rate charged and the operating revenues that would have been obtained from the same volume of business from the final set rate, through a temporary rate decrease for the period that the Commission sets.