Quick Answer
Yes, Medicare Part B covers Leqembi (lecanemab) for beneficiaries with early-stage Alzheimer's disease who meet CMS eligibility criteria. Coverage requires a confirmed Alzheimer's diagnosis, evidence of amyloid plaques, and treatment through a provider enrolled in a qualifying registry or clinical study. You pay 20% coinsurance after your Part B deductible. A Medigap plan can cover that 20%, significantly reducing your out-of-pocket costs for this expensive treatment.
Coverage Comparison by Plan Type
| Plan Type | Coverage | Notes |
|---|---|---|
| Medicare Part B (Outpatient) | Covered | Covers 80% of infusion cost after $283 Part B deductible; you pay 20% coinsurance |
| Medicare Part A (Inpatient) | Not Covered | Leqembi is an outpatient infusion - Part A does not apply |
| Medicare Advantage (Part C) | Covered | Must cover same services as Original Medicare; cost-sharing varies by plan |
| Medicare Supplement (Medigap) | Varies by Plan | Covers some or all of the 20% coinsurance left by Part B |
Understanding Your Coverage Options
Original Medicare (Part B)
Covered with eligibility requirementsMedicare Part B covers Leqembi as a physician-administered drug under its outpatient drug benefit. Because Leqembi is given as an intravenous infusion in a clinical setting, it falls under Part B rather than Part D (which covers self-administered drugs).
CMS expanded coverage for Leqembi in 2023 following its traditional FDA approval, requiring that treatment occur through a provider participating in a qualifying registry. Patients must have a confirmed diagnosis of mild cognitive impairment or mild dementia due to Alzheimer's disease, along with confirmed amyloid pathology (typically via PET scan or cerebrospinal fluid test).
Leqembi is administered as an IV infusion every two weeks. The drug's list price is approximately $26,500 per year, making the 20% Part B coinsurance a significant expense without supplemental coverage.
What It Covers
- Leqembi (lecanemab) infusions every two weeks
- Amyloid PET scan or CSF test to confirm diagnosis (when medically necessary)
- MRI monitoring scans required during treatment
- Physician supervision and administration fees
- Related infusion center facility fees
What It Doesn't Cover
- Treatment for moderate or severe Alzheimer's disease
- Leqembi for patients without confirmed amyloid pathology
- Treatment outside of a qualifying registry or clinical study (prior to full CMS approval)
- Self-administered Alzheimer's medications (covered under Part D instead)
Leqembi costs approximately $26,500/year. With Part B, you pay 20% coinsurance (~$5,300/year) after the $283 annual deductible. Medigap Plan G would cover the 20%, leaving only the $283 deductible.
Medicare Advantage (Part C)
Covered - cost-sharing varies by planMedicare Advantage plans are required to cover Leqembi under the same rules as Original Medicare. However, your actual out-of-pocket costs depend on your specific plan's cost-sharing structure, and you must use in-network providers and infusion centers.
Some Medicare Advantage plans may require prior authorization before approving Leqembi treatment. Contact your plan before beginning treatment to understand the approval process and confirm that your neurologist and infusion center are in-network.
What It Covers
- Leqembi infusions at in-network facilities
- Required monitoring scans and physician visits
- Infusion administration fees
What It Doesn't Cover
- Out-of-network infusion centers (unless plan has out-of-network benefits)
- Treatment not pre-authorized by the plan
Prior Authorization May be Required
Many Medicare Advantage plans require prior authorization for Leqembi. Contact your plan before scheduling your first infusion to avoid unexpected denials or costs.
Medicare Supplement (Medigap)
Covers some or all of Original Medicare's cost-sharingMedigap plans can dramatically reduce the out-of-pocket cost of Leqembi treatment. Because Leqembi is covered by Part B, Medigap plans that cover Part B coinsurance will pay the 20% that Original Medicare leaves behind.
Medigap Plan G is the most comprehensive plan available to new Medicare enrollees. After you pay the $283 annual Part B deductible, Plan G covers 100% of the Part B coinsurance - meaning your annual Leqembi cost could be as low as $283 instead of over $5,000.
What It Covers
- Part B coinsurance (20%) - covered by most Medigap plans
- Part B deductible - covered by Plan C and Plan F (for those eligible before Jan 1, 2020)
- Excess charges - covered by Plans F and G
What It Doesn't Cover
- Services not covered by Original Medicare
- Part D prescription drugs (Medigap does not cover Part D)
With Medigap Plan G, your annual out-of-pocket cost for Leqembi infusions is just the $283 Part B deductible. Without a supplement, you could owe over $5,000 per year in coinsurance.
Estimated Leqembi Costs under Medicare (2026)
| Cost Item | Annual Amount | Your Cost (No Supplement) | Your Cost (With Plan G) |
|---|---|---|---|
| Leqembi drug cost (list price) | ~$26,500/year | 20% coinsurance = ~$5,300/year | $283 deductible only |
| Amyloid PET scan (initial diagnosis) | ~$3,000–$5,000 | 20% coinsurance after deductible | $0 after deductible |
| MRI monitoring scans (required during treatment) | ~$500–$1,500/year | 20% coinsurance after deductible | $0 after deductible |
| Infusion administration fees | Varies by facility | 20% coinsurance after deductible | $0 after deductible |
✦ Eligibility Requirements for Medicare Coverage of Leqembi
Who Qualifies for Medicare Coverage
To receive Medicare coverage for Leqembi, you must have a confirmed diagnosis of mild cognitive impairment (MCI) or mild dementia due to Alzheimer's disease, confirmed amyloid pathology (via PET scan or cerebrospinal fluid test), and treatment must be provided through a qualifying registry or CMS-approved clinical study. Patients with moderate or severe Alzheimer's disease do not currently qualify.
CMS coverage requirements for Leqembi may change as more clinical data becomes available. Always confirm current eligibility criteria with your neurologist and Medicare plan before beginning treatment.
ARIA: A Key Safety Consideration
Leqembi carries a risk of amyloid-related imaging abnormalities (ARIA), which are brain swelling or microbleeds that can occur during treatment. Medicare covers the MRI monitoring scans required to detect ARIA. Patients with certain genetic profiles (APOE4 carriers) have a higher risk of ARIA and should discuss this with their neurologist before starting treatment.
✦ Frequently Asked Questions
David Haass
AuthorDavid Haass is the Chief Technology Officer and Co-Founder of Elite Insurance Partners and MedicareFAQ.com. He is a member and regular contributor to Forbes Finance Council.
Ashlee Zareczny
ReviewerAshlee Zareczny is a licensed Medicare agent in all 50 states dedicated to educating those eligible for Medicare. She trains agents on CMS compliance guidelines.