Md. Code, Health Occupations § 14–605

(a) This section does not apply to a physician or group of physicians who:

(1) Have exclusive contracts with a health maintenance organization;

(2) Treat only the patients of the health maintenance organization; and

(3) Agree to accept full assignment for covered services rendered.

(b) If a physician is engaged in the private practice of medicine in this State, the physician shall display a notice written in English that is plainly visible to patients in the office of the physician concerning whether the physician:

(1) Is a participating physician under the Medicare program and, therefore, accepts assignment for all Medicare claims;

(2) Accepts Medicare assignment on a case-by-case basis; or

(3) Does not accept Medicare assignment in any case.