Md. Code, Financial Institutions § 12–120

(a) Except as provided in § 15-802(b) of the Commercial Law Article and subsection (b) of this section, a licensee may not charge any other fee, including late fees or other service fees, for accepting or cashing a payment instrument in excess of the greater of:

(1) 2% of the face amount of the payment instrument or $3, if the payment instrument is issued by the federal government or a state or local government;

(2) 10% of the face amount of a payment instrument or $5, if the payment instrument is a personal check; or

(3) 4% of the face amount of the payment instrument or $5, for any other payment instrument.

(b) A licensee may charge a customer a one-time membership fee not to exceed $5.