Md. Code, Corporations and Associations § 5–6B–29

(a) Subject to the requirements of this section, a proprietary lease or the bylaws of a cooperative housing corporation may provide for a late charge of no more than $15 or one–tenth of the total amount of any delinquent assessment or installment owed by a member, whichever is greater.

(b) A late charge may not be imposed more than once for the same delinquent assessment or installment.

(c) A late charge may only be imposed if the delinquency has continued for a period of 10 days or more.