This is process information, not medical advice

Everything below describes how Medicare and insurance coverage decisions and appeals work — not whether any particular drug is right for any particular person. Coverage rules change, and every plan has the final say on its own current criteria. Confirm anything here against the plan, the prescriber's office, or 1-800-MEDICARE before you act on it. Nothing on this page is a recommendation to start, continue, or avoid any treatment. For what the trials found and the risks, see lecanemab and donanemab: do they work?

Compiled 2026-09-28. Every figure below carries the source it came from and whether that source is a government primary source or a named secondary one — see the provenance section at the bottom.

Which programme pays for your drug

Anti-amyloid monoclonal antibody infusions (lecanemab/Leqembi, donanemab/Kisunla) are physician-administered and bill under Medicare Part B, the medical benefit. The older small-molecule pills (donepezil, memantine, rivastigmine, galantamine) are self-administered and bill under Medicare Part D, the drug benefit. Which programme pays determines which prior-authorization process applies, which appeal ladder applies, and which cost-sharing applies — filing an appeal against the wrong programme's process wastes the clock on a real deadline.

Part B — the medical benefit

Physician-administered infusions: lecanemab (Leqembi), donanemab (Kisunla). Billed by the infusion site, not a pharmacy. Prior authorization, if required, runs through the plan's medical/utilization-management process, and appeals follow the Part B ladder below.

Drug · year	Part B spending	Claims
lecanemab (Leqembi) · 2023	$4,243,344	4,161
lecanemab (Leqembi) · 2024	$90,371,611	86,149
donanemab (Kisunla) · 2024	$5,246,234	2,832

Part D — the drug benefit

Self-administered pills: donepezil, memantine, rivastigmine, galantamine. Filled at a pharmacy. Prior authorization and step therapy, if the plan uses them, run through the Part D plan's own process, and appeals follow the Part D ladder below.

Drug · year	Part D spending	Claims
lecanemab (Leqembi) · 2023	$17,321	12
lecanemab (Leqembi) · 2024	$514,268	399
donanemab (Kisunla) · 2024	$16,976	16
donepezil (Aricept) · 2024	$101,902,812	8,069,366
memantine (Namenda) · 2024	$166,970,486	5,630,610

Why this matters more than it looks like it should

Lecanemab's 2024 Part B spending ($90.37M) was about 176x its 2024 Part D spending ($514,268) — nearly all real-world use bills through the medical benefit, not the pharmacy benefit. The figures come from CMS's Medicare Part B and Part D drug spending data, and each one carries its own CMS source link.

If paperwork gets filed against the wrong programme's process, the real clock on a real deadline keeps running while the wrong desk reviews it. Confirm which programme pays before filing anything.

Do you meet the coverage rule?

CMS National Coverage Determination 200.3, "Monoclonal Antibodies Directed Against Amyloid for the Treatment of Alzheimer's Disease (AD)", effective 2022-04-07, sets the Part B coverage rule for the antibodies. It has three gates. A patient who fails any one of them has no Part B coverage path for the antibody under the current rule — this is worth learning before a denial, not after.

Gate 1: Qualifying diagnosis

A clinical diagnosis of mild cognitive impairment (MCI) due to Alzheimer's disease, OR mild Alzheimer's disease dementia.

Fails if: The patient is asymptomatic, has moderate-to-severe dementia, or has a dementia diagnosis not attributed to Alzheimer's disease.
Gate 2: Confirmed amyloid pathology

Both qualifying diagnoses above must also have "confirmed presence of amyloid beta pathology consistent with AD" — the NCD does not itself mandate a specific test, but confirmation is typically by amyloid PET scan or CSF analysis.

Fails if: Amyloid status is not confirmed, or a test was ordered but not yet resulted.
Gate 3: Furnished within a qualifying research/registry context

Coverage exists only when the antibody is furnished under an FDA-approved randomized controlled trial run under an IND, a CMS-approved prospective comparative study, or an NIH-supported trial furnished per the FDA-approved indication.

Fails if: The prescriber and site are not enrolled in one of the CMS-approved studies/registries listed below at the time of infusion.

Nationally non-covered: "Monoclonal antibodies directed against amyloid for the treatment of AD provided outside of an FDA-approved randomized controlled trial, CMS-approved studies, or studies supported by the NIH, are nationally non-covered." CMS NCD 200.3

A patient who fails any one of these three gates has no path to Part B coverage for the antibody under the current NCD — not a denial to appeal, a structural non-coverage. Confirming diagnosis, amyloid status, and registry enrollment before treatment starts avoids a denial built into the rule itself.

Gate 3 in practice: the current CED registry list

As of 2026-09-28, CMS names four studies/registries that currently meet the registry requirement CMS, primary:

Alzheimer's National Registry for Treatment and Diagnostics

Alzheimer's Disease and Related Disorders Association, Inc.

NCT06170268 · CMS-approved 2024-01-29

Georgia Memory Net Anti-Amyloid Monoclonal Antibody Registry

Emory University

NCT05999084 · CMS-approved 2023-11-14

A Prospective Comparative Study Of Monoclonal Antibodies For The Treatment Of Alzheimer's Disease

Beth Israel Deaconess Medical Center

NCT05925621 · CMS-approved 2023-07-11

Prospective Study on Anti-Amyloid-β Monoclonal Antibodies (The Anti-Aβ mAb CED Study)

Not stated on the CMS page

NCT06058234 · CMS-approved 2023-07-06

CMS's own page lists these four as currently meeting the CED requirement. It gives no patient-facing enrollment portal or locator — only ClinicalTrials.gov links per study — and its only stated procedural instruction is aimed at the prescribing clinician's practice, not the patient: "Prescribing clinicians or their staff shall submit at first baseline treatment via the dedicated CMS CED data submission portal and every six months for up to 24 months (five total assessments)." A patient should ask the prescribing clinic directly whether it is enrolled in one of these before scheduling infusion.

Could not confirm: Whether additional registries have been approved since the page was last checked, and whether every individual health system participating in one of these four is itself actively enrolling new patients, could not be confirmed beyond what CMS's page states.

The prior-authorization checklist

What a real, published payer policy for lecanemab requires — Aetna's own Clinical Policy Bulletin 1026 — Lecanemab-irmb (Leqembi) payer PDF, secondary, given here as a worked example of what this kind of paperwork actually asks for, not as a universal standard. These are two payers' own published policies, named and dated. They are examples of what a real published PA policy for lecanemab looks like, not a universal standard — every plan sets its own criteria, and a Medicare Advantage plan's PA criteria can differ from Original Medicare's NCD and from these commercial examples. Confirm the specific plan's current criteria directly.

Diagnosis of Alzheimer's disease at Clinical Stage 3 or 4
Confirmed amyloid pathology by either: PET scan showing amyloid pathology, OR lumbar puncture/CSF showing a low Aβ42/Aβ40 ratio, elevated P-tau/Aβ42 ratio, or elevated T-tau/Aβ42 ratio
Prescribed by, or in consultation with, a geriatrician, neurologist, psychiatrist, or neuropsychiatrist
Baseline brain MRI within one year before treatment starts
Follow-up brain MRI approximately one week before the 3rd, 5th, 7th, and 14th doses (ARIA monitoring)
Enrollment in a provider-enrolled patient registry that collects Alzheimer's treatment information (Aetna's policy names the Alzheimer's Network for Treatment and Diagnostics as an example)

Not independently verified here: UnitedHealthcare's published commercial medical drug policy PDF for Leqembi and a Medicare Advantage plan's (Commonwealth Care Alliance) medical necessity guideline for Leqembi were both located and are publicly posted, but their PDF text could not be reliably extracted for direct quotation in this pass. They are not cited as fact here for that reason. URLs, for a human to check directly: https://www.uhcprovider.com/content/dam/provider/docs/public/policies/comm-medical-drug/leqembi.pdf and https://www.commonwealthcarealliance.org/ma/wp-content/uploads/2026/01/Leqembi-lecanemab-irmb_121.pdf

On MMSE / CDR-SB score thresholds

The NCD itself specifies a diagnosis (MCI due to AD / mild AD dementia) and confirmed amyloid pathology, but does not publish a specific MMSE or CDR-SB numeric cutoff. Aetna's own published criteria (above) reference "Clinical Stage 3 or 4" rather than a specific test score. We could not verify a single universal MMSE or CDR-SB cutoff that applies across payers, and are not stating one. A specific plan's own PA form, if it uses a numeric threshold, will say so — ask the prescriber's office to check the specific plan's current form rather than assuming a number.

Part D: step therapy and the exceptions process

Step therapy is a form of Part D prior authorization that requires trying a specified, usually less expensive drug the plan prefers before the plan will cover a costlier alternative for the same condition.

Either the enrollee or the prescriber can ask for an exception. A statement from the prescriber supporting medical necessity for skipping the preferred drug is required. Standard decisions are due within 72 hours. If the prescriber states that waiting for a standard decision could seriously jeopardize the enrollee's health, the plan must decide within 24 hours. medicare.gov

If you are denied

The appeal ladder depends on which programme paid (or would have paid) the claim — see which programme pays above. Both ladders let you ask for an expedited review when a prescriber states that waiting for the standard timeframe could seriously jeopardize health; otherwise the standard timeframes below apply. Dollar thresholds shown are for calendar year 2026.

Part B ladder — for the antibody infusions CMS / medicare.gov

Redetermination

Decided by
Medicare Administrative Contractor (MAC)

File within
120 days from receipt of the Medicare Summary Notice / initial determination

Decision due
60 days after the MAC receives the request
Reconsideration

Decided by
Qualified Independent Contractor (QIC)

File within
180 days from receipt of the redetermination decision

Decision due
60 days after the QIC receives the request
ALJ hearing

Decided by
Administrative Law Judge or attorney adjudicator, Office of Medicare Hearings and Appeals (OMHA)

File within
60 days from receipt of the QIC's reconsideration decision

Decision due
90 days (standard)

Dollar threshold
$200 amount in controversy for calendar year 2026
Medicare Appeals Council review

Decided by
Medicare Appeals Council (Departmental Appeals Board)

File within
60 days from receipt of the ALJ's decision

Decision due
Not published as a fixed number of days in the sources checked
Judicial review

Decided by
U.S. District Court

File within
60 days from receipt of the Appeals Council's decision

Decision due
None

Dollar threshold
$1,960 amount in controversy for calendar year 2026

Part D ladder — for donepezil, memantine, rivastigmine, galantamine CMS / medicare.gov

Redetermination

Decided by
The Part D plan itself

File within
65 days from the date on the coverage determination denial notice

Decision due
7 days standard (benefit), 14 days standard (payment reimbursement), 72 hours expedited
Reconsideration

Decided by
Independent Review Entity (IRE) under contract to CMS

File within
60 days from the plan's redetermination decision

Decision due
7 days standard (benefit), 14 days standard (payment), 72 hours expedited
ALJ hearing

Decided by
Administrative Law Judge or attorney adjudicator, OMHA

File within
60 days from the IRE's decision

Decision due
90 days (standard)

Dollar threshold
$200 amount in controversy for calendar year 2026
Medicare Appeals Council review

Decided by
Medicare Appeals Council (Departmental Appeals Board)

File within
60 days from the ALJ's decision

Decision due
90 days (standard)
Judicial review

Decided by
U.S. District Court

File within
60 days from the Council's decision

Decision due
None

Dollar threshold
$1,960 amount in controversy for calendar year 2026

The $200 (ALJ) and $1,960 (judicial review) amount-in-controversy figures for calendar year 2026 come from the CMS-published Federal Register notice adjusting these thresholds annually; the same two figures apply to both the Part B and Part D ladders. A prior year's figure (e.g. $180/$1,840, current in 2024) will appear on some older secondary pages — the 2026 figures above supersede those for appeals filed in 2026.

What a denial like this usually turns on

This is not a statistic on how often lecanemab/donanemab are denied — we found claims of high commercial denial rates in industry press but could not fetch the underlying primary source to verify a specific percentage, so no denial-rate figure is stated on this page. What follows instead are denial reasons that follow directly and verifiably from the coverage requirements documented above (the NCD's three gates and payer PA criteria), not from an unverified statistic.

Diagnosis does not match the covered category (asymptomatic, or moderate/severe dementia rather than MCI/mild dementia due to AD).
Amyloid pathology not confirmed, or the confirming test result was not yet available/submitted at the time of the request.
Prescribing site or clinician not enrolled in one of the CMS-approved CED studies/registries at the time of infusion.
Missing or out-of-window baseline or monitoring MRI (ARIA surveillance imaging tied to specific dose numbers).
Prescriber specialty requirement not met, where a payer's own policy requires prescribing by, or in consultation with, a geriatrician, neurologist, psychiatrist, or neuropsychiatrist.
Missing prior-authorization documentation altogether — a claim submitted for a Part B drug without a completed PA request on file is a distinct, purely administrative denial reason separate from any clinical criterion.

Paying less

$23,940

Extra Help annual income limit, single (2026)

Couple: $32,460. Resources: $18,090 single / $36,100 couple. Source: SSA Program Operations Manual System (POMS) HI 03001.020, dated 2026-02-11

$2,100

Part D out-of-pocket cap (2026)

Once a Part D enrollee's out-of-pocket spending on covered drugs reaches this amount in the calendar year, they owe nothing more for covered Part D drugs for the rest of the year. This cap does not apply to Part B drugs (the antibody infusions) — it is a Part D-only protection. Source: medicare.gov

$283

Part B annual deductible (2026)

Then 20% of the Medicare-approved amount, for most Part B services and drugs, including antibody infusions, unless a Medigap policy or Medicare Advantage plan's own cost-sharing structure changes this. Source: CMS, 2026 Parts A & B premiums and deductibles

Extra Help (the Part D Low-Income Subsidy) reduces or eliminates the Part D premium and deductible and caps copays, for those under the income and resource limits above. Since January 1, 2024, everyone who qualifies for Extra Help receives the full subsidy — the older partial-subsidy tiers (25%/50%/75%) no longer apply to new eligibility determinations. Apply at ssa.gov/medicare/part-d-extra-help.

Medicare Prescription Payment Plan ("smoothing"): An option to spread out-of-pocket Part D drug costs across the calendar year (January–December) in capped monthly amounts, instead of paying the full amount at the pharmacy counter when a prescription is filled. It does not lower drug costs or save money — it only changes when the same total is paid. Part D drugs. Does not apply to Part B-administered infusions.

Manufacturer patient-assistance and copay programmes

lecanemab (Leqembi) · Eisai

LEQEMBI iQLIK Copay Assistance Program (commercial copay card) — Eligible commercially insured patients may pay as little as $0 per prescription/infusion, up to an annual program limit.
Not usable on Medicare: The offer is not valid for patients enrolled in state and federal healthcare programs, including Medicare, Medicaid, Medigap, VA, DoD, or TRICARE. Because the large majority of lecanemab patients are Medicare beneficiaries (see the Part B and Part D split above), most patients on this drug cannot use this card at all — federal law bars manufacturer copay coupons for federal healthcare program beneficiaries. secondary

Referenced as part of the "LEQEMBI Companion" program, but we could not confirm specific eligibility terms for a free-drug/uninsured-patient program from the pages we could fetch. Call Eisai Patient Support at 1-833-453-7362 (Mon–Fri, 8am–8pm ET) to ask directly.

donanemab (Kisunla) · Eli Lilly

Kisunla Savings Card (commercial copay card) — Reduces copay/coinsurance for the drug itself, up to a monthly and annual maximum; does not cover infusion/administration or facility charges.
Not usable on Medicare: Restricted to patients with commercial drug insurance; patients enrolled in Medicare, Medicaid, or other government healthcare programs are not eligible. Same structural gap as Leqembi's card: most donanemab patients are on Medicare and cannot use this program. secondary
Lilly Cares Foundation (charitable patient assistance program (free drug for qualifying uninsured/low-income patients)) — Provides Lilly medicines at no cost to patients who meet income and insurance-status eligibility criteria.
unconfirmed whether Medicare beneficiaries who lack Part B drug coverage specifically can qualify — ask Lilly Cares directly. Contact: 1-800-545-6962. secondary
Lilly Support Services (benefits investigation / navigation support (not a discount)) — Registered-nurse support and a benefits investigation to estimate real out-of-pocket cost before starting treatment. Contact: 1-800-545-5979. secondary

donepezil, memantine, rivastigmine, galantamine · multiple (all now available generically)

All four older symptomatic drugs are available as low-cost generics (in CMS's Part D drug spending data, their Medicare cost per claim is in the single-digit to low-double-digit dollars). We did not find manufacturer brand-name copay programs actively worth citing for the generic forms; a state pharmacy assistance program or Extra Help is the more relevant cost-reduction path for these.

Getting help with the process itself

State Health Insurance Assistance Program (SHIP): A federally funded, free, unbiased Medicare counseling service in every state, for beneficiaries, families, and caregivers — not affiliated with any insurance company. Can help with: Understanding a denial notice, filing a redetermination or appeal, understanding Extra Help eligibility, and general plan comparison. Find yours at shiphelp.org or call 1-877-839-2675.

1-800-MEDICARE: 1-800-633-4227, 24 hours a day, 7 days a week, except some federal holidays.

Where this came from

This page describes insurance and Medicare PROCESS: how coverage decisions are made and appealed. It is not medical advice, it does not recommend any treatment, and coverage rules change. Confirm current rules with the specific plan, the prescriber's office, or 1-800-MEDICARE before acting.

What could not be confirmed

A specific, universal MMSE or CDR-SB numeric score threshold for anti-amyloid antibody coverage — not published in the NCD itself; payer-specific, and not confirmed as standardized.
Any denial-rate percentage for lecanemab or donanemab prior authorization requests — industry press claims exist but their primary source could not be fetched and verified in this pass.
UnitedHealthcare's and Commonwealth Care Alliance's exact published PA criteria text — PDFs located and publicly posted, but not reliably extractable for direct quotation; URLs are given so a reader can check them directly.
Whether the CED registry list has changed since 2026-09-28 — confirm at the CMS URL given, since CMS adds registries over time.
Eisai's specific free-drug patient assistance program eligibility terms for uninsured lecanemab patients.
Whether Lilly Cares Foundation extends to Medicare beneficiaries specifically for donanemab.

Source-type key

primary: A government source: CMS, medicare.gov, SSA, the Federal Register, or the FDA label.
secondary: A named non-government source: a specific payer's own published policy PDF, a manufacturer's own program page.
unconfirmed: Could not be verified from a source we could actually fetch; stated as unconfirmed rather than invented.

Every figure on this page comes from our prior-authorization dataset, compiled 2026-09-28. This is a summary of published government and payer sources, not medical advice, and coverage rules change — confirm current rules with the plan, the prescriber's office, or 1-800-MEDICARE.

Getting Alzheimer's drugs covered