Md. Code, Business Regulation § 8–102

(a) This title does not apply to a transaction of:

(1) the United States or an instrumentality of the United States; or

(2) a state or an instrumentality or political subdivision of a state.

(b) A county or municipal corporation of the State may not:

(1) require a person to get authorization to do business performing or selling a home improvement; or

(2) regulate the qualifications necessary to do that business.

(c) This title does not limit the power of a county or municipal corporation:

(1) to regulate the character, performance, or quality of a home improvement by having a system of inspections and permits designed to:

(i) ensure compliance with and help to enforce applicable State and local building laws; or

(ii) enforce other laws necessary to protect the public health and safety; or

(2) to adopt a system of inspections and permits that requires:

(i) submission to and approval by the county or municipal corporation of plans and specifications for an installation, before construction of the installation begins; and

(ii) inspection of work done.