Summary: The Centers for Medicare & Medicaid Services modified its coverage policy for monoclonal antibodies directed against amyloid for the treatment of Alzheimer's disease, effective May 15, 2026. Here's what billing teams need to know before that date.
This is a high-stakes policy for any practice or facility billing for lecanemab (Leqembi) or donanemab (Kisunla) under Medicare. The CMS monoclonal antibodies Alzheimer's disease coverage policy has been one of the most contested reimbursement questions in neurology and infusion billing since these drugs first hit the market. The May 15, 2026 modification continues that pattern—and if your team isn't current on the updated criteria, you're looking at claim denial exposure on some of the highest-cost infusion claims in the Medicare book.
This policy does not list specific CPT or HCPCS codes in the source data available. Relevant codes for anti-amyloid monoclonal antibody billing are discussed in context below, but confirm all codes against the current policy document before billing.
Quick-Reference Table
| Field | Detail |
|---|---|
| Payer | CMS |
| Policy | Monoclonal Antibodies Directed Against Amyloid for the Treatment of Alzheimer's Disease |
| Policy Code | N/A |
| Change Type | Modified |
| Effective Date | May 15, 2026 |
| Impact Level | High |
| Specialties Affected | Neurology, Geriatrics, Infusion Therapy, Hospital Outpatient, Nuclear Medicine, Radiology |
| Key Action | Audit your prior authorization workflows and documentation practices for anti-amyloid infusion claims before May 15, 2026 |
CMS Monoclonal Antibodies Alzheimer's Disease Coverage Criteria and Medical Necessity Requirements 2026
The Centers for Medicare & Medicaid Services has been modifying its anti-amyloid monoclonal antibody coverage policy in stages since 2023. The trajectory matters. CMS initially restricted coverage to patients enrolled in qualifying clinical trials under a Coverage with Evidence Development (CED) framework. That framework drew immediate criticism from patient advocates, neurologists, and industry—and CMS has been rolling it back incrementally ever since.
The May 15, 2026 effective date marks the latest modification in that rollback. Based on the direction CMS has taken with lecanemab and donanemab, the updated coverage policy expands access beyond the CED restrictions that defined earlier versions. That's directionally good for billing teams and for patients. But "expanded" doesn't mean "open"—medical necessity criteria remain specific, and documentation requirements are real.
What Medical Necessity Looks Like Under This Policy
CMS coverage for anti-amyloid monoclonal antibodies hinges on confirmed amyloid pathology. That means patients need documented evidence of amyloid plaques—either via amyloid PET imaging or cerebrospinal fluid (CSF) biomarker testing—before coverage applies. This is not a soft requirement. If the amyloid confirmation isn't in the record, the claim is vulnerable.
Patients also need a confirmed diagnosis of mild cognitive impairment (MCI) due to Alzheimer's disease or mild Alzheimer's disease dementia. Coverage does not extend to moderate or severe AD. That distinction matters for your ICD-10 coding—make sure your coders aren't reaching for a dementia code that puts the patient outside the covered severity range.
Medical necessity documentation should include the treating physician's clinical assessment, the stage of disease, and the amyloid confirmation method. Medicare Administrative Contractors have been auditing this heavily. Don't assume a prescription and an infusion order are enough.
Prior Authorization and Coverage Policy Requirements
Prior authorization requirements under this coverage policy vary by Medicare Advantage plan and by MAC jurisdiction for traditional Medicare. For traditional fee-for-service Medicare, check with your MAC on any pre-authorization or prior notification requirements that apply in your region. Medicare Advantage plans layer their own prior auth requirements on top of the CMS national coverage policy—and those can be significantly more restrictive.
If your practice sees a Medicare Advantage population for anti-amyloid infusions, map out each plan's prior authorization requirements separately. Treating the MA plans as identical to traditional Medicare on this drug class is a billing mistake that generates denials.
CMS Monoclonal Antibodies Alzheimer's Disease Exclusions and Non-Covered Indications
CMS does not cover anti-amyloid monoclonal antibodies for moderate or severe Alzheimer's disease. The clinical trial data supporting these drugs enrolled patients with early-stage disease, and CMS has held that line on coverage.
Patients without confirmed amyloid pathology are also outside the covered population. A clinical diagnosis of Alzheimer's without biomarker confirmation is not sufficient for coverage under this policy. Your intake process needs to catch this before the drug is administered—not after.
Coverage also does not extend to off-label use for other forms of dementia. Lecanemab and donanemab are specifically directed against amyloid; their use in non-AD dementia (vascular dementia, Lewy body dementia, frontotemporal dementia) falls outside the scope of this coverage policy.
Patients who have a contraindication to treatment—including certain APOE ε4 genotypes depending on the drug's labeling—may face coverage limitations as well. Work with your medical director and compliance officer to establish clear internal criteria for patient selection that align with both the drug's FDA labeling and CMS coverage requirements.
Coverage Indications at a Glance
The source policy data does not include a line-by-line indications table. Based on established CMS coverage policy for this drug class, the general indication-level picture looks like this:
| Indication | Status | Notes |
|---|---|---|
| MCI due to Alzheimer's disease with confirmed amyloid pathology | Covered | Amyloid confirmation via PET or CSF biomarker required; prior auth rules vary by plan |
| Mild Alzheimer's disease dementia with confirmed amyloid pathology | Covered | Same documentation requirements; ICD-10 specificity required |
| Moderate or severe Alzheimer's disease | Not Covered | Outside CMS-defined covered population |
| AD diagnosis without amyloid biomarker confirmation | Not Covered | Clinical diagnosis alone insufficient |
| Off-label use for non-AD dementia | Not Covered | Outside scope of this coverage policy |
Confirm each row against the full policy document at the source URL. These indications reflect the established CMS framework, but the May 15, 2026 modification may adjust specific language or add new criteria.
CMS Monoclonal Antibodies Alzheimer's Disease Billing Guidelines and Action Items 2026
The real issue here is documentation. Anti-amyloid monoclonal antibody billing is expensive per claim, which means MACs and Medicare Advantage plans scrutinize these claims hard. Your billing guidelines need to be airtight before May 15, 2026.
| # | Action Item |
|---|---|
| 1 | Pull your current documentation requirements checklist and update it before May 15, 2026. Confirm that amyloid confirmation (PET or CSF), disease staging, and physician attestation are all captured in the record before billing. A missing biomarker result is a clean path to claim denial. |
| 2 | Audit your prior authorization workflow for Medicare Advantage plans. Each plan may have different prior auth requirements layered on top of the CMS coverage policy. Build a payer-specific PA grid for every MA plan in your book that covers patients receiving these drugs. |
| 3 | Verify your ICD-10 coding maps to the covered severity range. Mild cognitive impairment and mild Alzheimer's disease dementia are covered. Moderate and severe are not. Your coders need to know which codes map to which stage—and your documentation needs to support the code selected. |
| 4 | Confirm drug-specific HCPCS coding with your MAC. Lecanemab and donanemab have distinct HCPCS codes. The underlying CMS coverage policy does not list specific codes in the source data for this modification, so pull the current code-to-drug mapping from your MAC's billing guidelines before the May 15 effective date. |
| 5 | Reconcile infusion administration codes. Anti-amyloid monoclonal antibodies are administered by intravenous infusion. Your charge capture should include the appropriate infusion administration codes alongside the drug HCPCS code. Confirm whether your facility or practice setting changes which administration codes apply. |
| 6 | Loop in your compliance officer before May 15, 2026. This drug class carries significant reimbursement per claim and significant audit risk. If you're not sure how the updated criteria apply to your patient population or your documentation practices, get your compliance officer involved before the effective date—not after a denial. |
| Previous Version | Current Version |
|---|---|
| Coverage is considered experimental and investigational for all indications | Coverage is considered medically necessary when specific criteria are met |
| Prior authorization is not required | Prior authorization is required for initial treatment |
| Documentation must include clinical history | Documentation must include clinical history |
| Re-review every 24 months | Re-review every 12 months with updated clinical documentation |
CPT, HCPCS, and ICD-10 Codes for Anti-Amyloid Monoclonal Antibodies Under This CMS Policy
The source policy data for this modification does not include specific CPT, HCPCS, or ICD-10 codes. Do not use codes from this post as the sole basis for billing. Confirm all codes against the current policy document and your MAC's billing guidelines.
Codes to Confirm with Your MAC
The following code types are relevant to anti-amyloid monoclonal antibody billing and should be confirmed against current payer guidance:
| Code Type | What to Confirm |
|---|---|
| Drug HCPCS codes | Payer-specific HCPCS codes for lecanemab and donanemab; these are assigned by CMS and subject to change |
| IV infusion administration codes | CPT codes for initial and subsequent infusion hours; setting-specific (hospital outpatient vs. office) |
| Amyloid PET codes | HCPCS codes for amyloid PET imaging used to confirm diagnosis; coverage rules for these are a separate but related issue |
| ICD-10-CM diagnosis codes | Codes for MCI due to AD vs. mild AD dementia; confirm you are not using codes that map to moderate or severe disease |
Until the full policy text is available in the source document, treat any code list you're currently using as provisional. Pull the updated policy at the CMS source and cross-reference against your charge capture before May 15.
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