A request for review of a denial of coverage of a particular medical service or inadequate payment for services already received. Medicare beneficiaries have the right to appeal in either of these circumstances, whether they are enrolled in traditional Medicare or in a Medicare Advantage plan. Under the ACA, all consumers have the right to appeal decisions, including coverage denials and rescissions, made by their health plans first through the plan’s internal process and then through an outside, independent decision-maker. (Also see grievance.)