A National Coverage Determination (NCD) is CMS policy that applies in every state. A Local Coverage Determination (LCD) is a Medicare Administrative Contractor's coverage decision for its own jurisdiction. Before billing, check the NCD first, then the LCD for your MAC, on the version effective for the date of service.
A claim denied for medical necessity has not always failed on clinical grounds. The diagnosis code may not appear on the list the contractor publishes for that service, the documentation may not carry an element the policy requires, or the coder may have checked a policy belonging to a different jurisdiction. The underlying rules are public and free to read. The difficulty is knowing which document governs, and where inside it the operative detail sits.
What is a National Coverage Determination (NCD)?
An NCD is national policy granting, limiting, or excluding Medicare coverage for a specific item or service. CMS develops and publishes NCDs through an evidence-based process with public participation, and they apply to all states . MACs are required to follow them.
CMS materials may identify separate effective and implementation dates for an NCD and its related claims-processing instructions. Check the decision memorandum and the applicable transmittal to establish when the coverage policy applies and when contractors are instructed to implement the changes.
What is a Local Coverage Determination (LCD)?
An LCD is a decision by a MAC on whether a service or item is reasonable and necessary, and therefore covered by Medicare, within the jurisdiction that MAC oversees. A MAC may develop an LCD when no NCD addresses the service, or as a supplement to an NCD, provided the local policy does not conflict with national coverage policy. LCD document IDs begin with "L"; proposed LCDs begin with "DL."
Two process facts govern the version you should be reading. Per CMS Program Integrity Manual Chapter 13 , publication of a proposed LCD on the Medicare Coverage Database opens the public comment process, and publication of the final LCD starts a minimum 45-calendar-day notice period before it can take effect (§13.2.4, §13.2.6). MACs may also revise or retire existing LCDs on their own initiative (§13.3). The process and notice requirements depend on the type of change, so verify the current effective version rather than relying on a previously saved policy.
What is the difference between an LCD and an NCD?
| NCD | LCD | |
|---|---|---|
| Issued by | CMS | A Medicare Administrative Contractor |
| Applies to | All states | That MAC's jurisdiction only |
| When it applies | Controls wherever it speaks to the service | Where no NCD exists, or where an NCD needs local definition |
| Relationship | MACs are required to follow NCDs | Cannot contradict an NCD; may clarify one |
| Document ID | Section number, for example NCD 20.8.3 | Begins with L, for example L12345 |
| When it changes | Carries its own effective and implementation dates | A new final LCD generally has a minimum 45-day notice period; revision and retirement requirements depend on the change |
CMS sets out the interaction in its document type descriptions . Where an NCD does not exclude or limit an indication, or does not mention the item at all, coverage may fall to the MAC's discretion under an LCD, within the bounds national policy sets. Where neither document speaks to the service, the claim is still assessed under the applicable Medicare benefit category, the statutory and regulatory requirements, the manual instructions that apply, and the reasonable and necessary standard. An article may carry billing or coding guidance in that situation, but it is not a coverage determination and does not stand in for an LCD or NCD. The absence of an LCD is not evidence that a service is covered.
Where do the ICD-10 and CPT code lists live?
Not in the LCD, and this is where a coverage check most often comes back empty for teams working from older training.
CMS moved them. Program Integrity Manual Chapter 13 states at §13.5 that it is no longer appropriate to include CPT or ICD-10-CM codes in LCDs, and that all such codes shall be removed from LCDs and placed in billing and coding articles or policy articles published to the Medicare Coverage Database. The instruction took effect October 3, 2018 and was implemented January 8, 2019. Where a MAC provides coding and billing information to help implement a coverage policy, it publishes that article at the same time as the LCD.
DME billing is the exception. The Medicare Coverage Database help text states that for Durable Medical Equipment MACs only, CPT and HCPCS codes remain located in LCDs, and that all other codes, meaning ICD-10, bill type, and revenue, have moved to Articles for DME MACs. For other MAC policies the codes are generally in the billing and coding article. Check the document type and the contractor rather than assuming every code list sits in the article.
Depending on the policy and contractor, the associated article may carry applicable procedure codes, diagnosis codes, bill types, revenue codes, and modifier instructions. Those lists tell you which services the policy applies to, and which diagnosis codes support or do not support medical necessity. Article IDs begin with "A"; draft articles supporting a proposed LCD begin with "DA."
The LCD gives you the coverage criteria. The article gives you the codes that express them. Read one without the other and you miss the part the claim is adjudicated on.
Billing and coding articles can also be revised, replaced, consolidated, or retired, so check the current version in the Medicare Coverage Database rather than a saved copy.
How do you check LCD and NCD coverage before billing?
Work the Medicare Coverage Database in this order. It supports search by keyword, CPT or HCPCS code, ICD-10-CM code, document ID, contractor name, and state or CMS region.
- Confirm the plan. Original Medicare applies national and local Medicare coverage policy directly. Medicare Advantage plans must comply with applicable NCDs, Traditional Medicare benefit conditions, and local contractor coverage decisions under 42 CFR 422.101(b) , but their process is not identical: a plan covering areas under more than one local policy may elect, with CMS approval, to apply the most beneficial policy uniformly (b)(3), and a plan may use publicly accessible, evidence-based internal criteria where Medicare coverage criteria are not fully established (b)(6). Check the plan's published policy alongside the Medicare coverage documents. Medicaid and commercial payers set their own rules, and this lookup does not settle coverage under either.
- Pin the service and the diagnosis against the record. Fix the CPT or HCPCS code you intend to report, including any modifier that changes the service described, and work from the documentation rather than the problem list.
- Search for an NCD first, then the LCD for the applicable MAC. National policy controls wherever it speaks to the service. For the local policy, the CMS provider assignment rules generally assign a provider or supplier to the MAC covering the state where it is located, and institutional providers to the MAC for the locale in which the provider is physically located. DMEPOS suppliers bill the DME MAC for where the beneficiary permanently resides, and Part B claims for Railroad Retirement Board beneficiaries go to the contractor the RRB designates. An LCD from the wrong jurisdiction is a different policy.
- Open the associated billing and coding article, on the version effective for the date of service. Take the covered and non-covered diagnosis code lists, frequency limits, and modifier requirements from there. Retired documents stay visible in the database, so confirm what was in force on the day the service was furnished rather than what the search returns first.
- Compare the criteria to the record, then route the gaps. Check indications, limitations, frequency, and any documentation element the policy names, remembering that a diagnosis code on the covered list does not substitute for documentation the policy requires. Missing documentation goes to a provider query and unsupported coding to a reviewer. Neither should leave in a claim.
Common coverage-checking errors include using an LCD from the wrong MAC jurisdiction, relying on an outdated policy, overlooking the associated billing and coding article, and treating a diagnosis code on the covered list as sufficient documentation of medical necessity.
What happens when a service does not meet coverage criteria?
The claim is at risk of denial as not reasonable and necessary, which leaves you a write-off or an appeal. Before that point, query the provider if supporting documentation exists but did not reach the note. Where the service was furnished for an indication the policy does not cover, beneficiary liability may be shiftable under Original Medicare through an Advance Beneficiary Notice of Noncoverage, though the circumstances and timing requirements are specific enough to belong in your compliance team's process rather than at the coder's desk. LCDs are also open to reconsideration requests, which is slow but real.
How does automated coding apply coverage checks at volume?
Nothing in that workflow is obscure. It costs time, and five steps on every Medicare chart compete with a turnaround target, which is the pressure that shortens checks on the charts that look routine.
MediCodio AI's CODIO AI engine checks code assignments against applicable LCD and NCD requirements during the coding workflow, flagging potential policy and documentation gaps before submission rather than after a denial. NCCI edits and MUE limits are checked in the same workflow, and Smart Payer Guidelines apply plan-specific requirements to the Medicaid and commercial volume that national and local Medicare policy does not reach. The checks run as the chart is coded, using the applicable policy and edit content maintained by the respective publishers.
Routing matters most on the charts where coverage is in question. Complete charts flow through AutoPilot for fully autonomous coding. Charts where the documentation is thin or contradictory stay in CoPilot, where certified coders review and finalize the output. Autonomous handling applies only to charts meeting the configured criteria, so when the engine identifies a potential gap against a coverage or documentation requirement, the chart routes to a certified coder rather than clearing automatically. Reviewers can then inspect the documentation evidence and the coding rationale behind each suggested code, which makes the review traceable rather than dependent on recall.
MediCodio AI supports coding and compliance review. It does not make Medicare coverage determinations or guarantee reimbursement. Payment remains subject to the applicable policy, the patient's circumstances, the documentation in the record, and the payer's adjudication.
Summary
NCDs are CMS policy applying nationally; LCDs are MAC decisions for one jurisdiction that may clarify an NCD but never contradict it. Billing teams need both, plus the Billing and Coding article carrying the code lists, on the version effective for the date of service. Volume defeats that process. MediCodio AI validates coding against LCD and NCD policy alongside NCCI and MUE checks as the claim is built, routing thin documentation to certified coders in CoPilot.
References
- CMS, Medicare Coverage Database and its document type descriptions and help text
- CMS, Medicare Program Integrity Manual, Chapter 13 , Rev. 863, §§13.1.1, 13.2.4, 13.2.6, 13.3, 13.5
- CMS, Medicare Administrative Contractors: Provider Assignment
- 42 CFR 422.101(b)