Maryland Code, State Finance and Procurement § 17-110

(b)(1) If a contractor has furnished 100% payment security and 100% performance security in accordance with this subtitle under a contract for construction awarded by a public body, the percentage specified in the contract for retainage may not exceed 5% of the total amount of the contract.

(2) In addition to retainage, a public body may withhold from payments otherwise due a contractor any amount that the public body reasonably believes necessary to protect the public body's interest.

(3) Except as provided in paragraph (4) of this subsection, within 120 days after satisfactory completion of a contract for construction, a public body shall release any retainage due to the contractor.

(4) If there is a dispute or contract claim between the contractor and the public body concerning the satisfactory completion of a contract for construction, the public body shall release the retainage to the contractor within 120 days after the resolution of the dispute or contract claim.

(c)(1) A contractor may not retain a percentage of payments due a subcontractor that exceeds the percentage of payments retained by the public body.

(2) Paragraph (1) of this subsection may not be construed to prohibit a contractor from withholding any amount in addition to retainage if the contractor determines that a subcontractor's performance under the subcontract provides reasonable grounds for withholding the additional amount.

(d)(1) A subcontractor may not retain a percentage of payments due a lower tier subcontractor that exceeds the percentage of payments retained from the subcontractor.

(2) Paragraph (1) of this subsection may not be construed to prohibit a subcontractor from withholding any amount in addition to retainage if the subcontractor determines that a lower tier subcontractor's performance under the subcontract provides reasonable grounds for withholding the additional amount.