A National Coverage Determination (NCD) is a Medicare-wide coverage policy set by CMS; a Local Coverage Determination (LCD) is set by the regional Medicare Administrative Contractor (MAC) for its jurisdiction. Where an NCD exists, it governs nationally; where it doesn't, the local MAC's LCD applies. Both spell out the conditions under which a service is covered — which is exactly what a medical-necessity appeal is argued against.
How they differ
- NCD — set by CMS, applies to all of Medicare nationwide.
- LCD — set by a MAC, applies only within that contractor's jurisdiction; LCDs for the same service can differ by region.
- Where an NCD addresses a service, it controls; LCDs fill the gaps the NCDs leave.
- Both are public and list covered indications, often by ICD-10 diagnosis.
Why they matter for appeals
A medical-necessity denial (CO-50) or a diagnosis denial (CO-11/CO-167) is decided against the governing coverage policy. The strongest appeal quotes that policy's own criteria and shows, point by point, that the documented record meets them. So the first step in many appeals is identifying whether an NCD or the local LCD applies — and reading its exact language.
Cite the policy that applies to your jurisdiction
Frequently asked
If both an NCD and an LCD exist, which controls?
Are LCDs the same in every state?
Primary sources: CMS — Medicare Coverage Database (LCDs & NCDs). General information, not legal or medical advice — confirm against the governing rule for the plan type.
When the appeal has to be written, and cited
Upload the denied EOB and Merits returns a complete, citation-verified appeal letter — the clinical argument, the payer's own coverage criteria, and your federal appeal rights — in about a minute.