A national coverage determination (NCD) is a US Government determination of whether Medicare will pay for an item or service.
Medicare coverage is limited to items and services considered “reasonable and necessary” for diagnosing or treating an illness or injury (and within the scope of a Medicare benefit category).
In the absence of an NCD, an item or service is covered at the discretion of the Medicare contractors based on a local coverage determination (LCD).
As of 2015, local coverage determinations only become public on an appeal and do not set a precedent.
External parties can request NCDs identifying an item or service as a potential benefit (or to prevent possible harm) to Medicare beneficiaries. External parties who may ask an NCD are Medicare beneficiaries, manufacturers, providers, suppliers, medical professional associations, or health plans.
NCDs can also be internally generated by the Centers for Medicare and Medicaid Services (CMS) under multiple circumstances.