Does Medicare Part D Cover Prolia? Part B, Biosimilars, $2,000 Cap

Yes, Medicare does cover Prolia (denosumab), and for most people it is covered under Part B as a provider-administered injection rather than through the Part D pharmacy benefit. After you meet the Part B deductible ($257 in 2025), you generally owe 20% of the Medicare-approved amount for each injection. If you pick up Prolia at a specialty pharmacy instead, Part D covers it, with costs that depend on your plan. Many Medicare plans are now switching their preferred denosumab product from Prolia to a lower-cost biosimilar, which changes what you may be asked to use and what you pay.

Prolia Under Part B: The Usual Path

Prolia is given as an injection every six months, almost always in a doctor’s office. Because of that, it is billed under Part B as a drug administered “incident to a physician’s service,” and each regional Medicare Administrative Contractor decides whether a given patient’s use is reasonable and necessary.¹ Prolia is not on Medicare’s Self-Administered Drug exclusion list, so it is not pushed off the medical benefit the way at-home drugs usually are.²

According to data cited by the manufacturer, Amgen, every Medicare Part B patient has access to Prolia as initial therapy with no prior authorization and no step therapy requirement.³ After the deductible, you pay the standard 20% Part B coinsurance.

What that looks like in dollars: the wholesale acquisition cost of Prolia is roughly $1,500 per 60 mg prefilled syringe, or about $3,000 a year at the usual twice-yearly schedule. A beneficiary without supplemental insurance would owe roughly $280 to $320 per injection as their 20% share.⁴ Amgen reports that about 86% of Part B patients end up paying nothing per syringe, because supplemental coverage such as Medigap, TRICARE, or employer insurance absorbs the coinsurance.³

Who Qualifies Medically

Your provider has to document that Prolia is medically necessary. Covered conditions include:

Postmenopausal osteoporosis in women at high risk for fracture, with records showing menopausal status, prior osteoporosis treatments and their results, fracture history, and risk factors.¹
Osteoporosis in men at high risk for fracture, including men on androgen deprivation therapy for nonmetastatic prostate cancer.¹
Glucocorticoid-induced osteoporosis in patients taking the equivalent of at least 7.5 mg of prednisone daily and expected to stay on treatment for at least six months.³
Bone loss caused by cancer treatment: breast cancer patients on aromatase inhibitors or men with nonmetastatic prostate cancer on androgen deprivation therapy.¹

Before your first injection, any low calcium level has to be corrected, and you must be taking at least 1,000 mg of calcium and 400 IU of vitamin D daily.¹ One boundary worth knowing: Prolia is not covered for osteopenia alone.⁵

There is also a home-health pathway. Medicare covers injectable osteoporosis drugs at home for postmenopausal women who have had an osteoporosis-related fracture, qualify for home health services, and have a provider certify they cannot self-administer and have no family member or caregiver who can. The nurse visit to give the shot costs nothing under this benefit.⁶

Prolia Under Part D: The Less Common Path

If you get Prolia dispensed through a specialty pharmacy instead of in a provider’s office, it is billed under Part D. As of February 2025, roughly 96% of Medicare Part D enrollees had Prolia on their plan’s formulary. About eight in ten of those patients face no prior authorization or step therapy; the rest may face one or both.⁷

Based on 2024 claims data, the average out-of-pocket cost for Prolia through Part D is about $274 every six months, or roughly $46 a month.⁷ Your actual cost depends on your plan’s tier for Prolia, your deductible, and which phase of the benefit you are in. Some plans require you to use a preferred specialty pharmacy such as CVS Specialty or CenterWell.⁸

The $2,000 Part D Cap and the Monthly Payment Option

Starting in 2025, Medicare Part D caps annual out-of-pocket drug spending at $2,000, rising to $2,100 in 2026.⁹ Once you reach the cap, your plan pays 100% of covered drug costs for the rest of the year, and the old coverage gap (the “donut hole”) is gone.¹⁰

The Medicare Prescription Payment Plan lets you spread that out-of-pocket amount across monthly installments instead of paying it all at the counter early in the year. Enrolling in January 2026 would spread the full $2,100 cap over about $175 a month; waiting until November would compress the same bill into just two months of much higher payments.¹¹

One important limit: the cap applies only to Part D. It does not reduce the 20% Part B coinsurance for a Prolia injection given in a doctor’s office.⁹

Biosimilars Are Replacing Prolia on Many Plans

The FDA has approved a wave of denosumab biosimilars, and Medicare plans are moving quickly to prefer them. If you have been on Prolia, your plan may now steer you to a biosimilar or require you to try one first. The FDA has designated several of these biosimilars as interchangeable, meaning they have no clinically meaningful differences from Prolia and, in most states, a pharmacy can substitute them without a new prescription.¹²

Changes already announced by major insurers:

UnitedHealthcare replaced Prolia with Jubbonti (and Xgeva with Wyost) across its Medicare Advantage plans, Medicare prescription drug plans, and most employer group Medicare Advantage plans as of September 1, 2025.¹³
Independence Blue Cross removed Prolia from its Medicare closed formularies on September 1, 2025, and made Jubbonti the preferred denosumab product. Existing Prolia prior authorizations transitioned automatically to Jubbonti for the rest of the authorization period.¹⁴
Blue Shield of California’s Medicare PPO plans require new denosumab patients to try Jubbonti before Prolia starting January 1, 2026. Exceptions need documentation of an intolerable side effect or a contraindication with Jubbonti.¹²
Priority Health dropped Prolia from coverage on January 1, 2026, adding Jubbonti at Tier 4 with quantity limits and moving Prolia to non-preferred status with prior authorization and step therapy.¹⁵
CVS Caremark will replace Prolia with the biosimilars Ospomyv and Stoboclo on its major national commercial formularies starting April 1, 2026. CVS Health has said those biosimilars run more than 50% below the brand per prescription.¹⁶

If you are enrolled in a Medicare Advantage plan, these shifts apply to you directly, since Part C plans are run by the same private insurers. Check your current formulary to see which denosumab product your plan now prefers and at what cost.¹³

If Your Plan Denies or Restricts Prolia

You can ask your Part D plan for a formulary exception when it prefers a biosimilar instead. Your prescriber submits a statement explaining that the preferred alternative has been or is likely to be less effective for you, or that it would cause an adverse effect. Plans must answer standard requests within 72 hours and expedited requests within 24 hours.¹⁷

If the exception is denied, the written notice will explain how to appeal. Part D appeals move through five levels: plan redetermination, then review by an independent review entity, then the Office of Medicare Hearings and Appeals (which requires a drug value of at least $200), then the Medicare Appeals Council, and finally federal district court (which requires a drug value of at least $1,960 in 2026). Standard decisions at the first two levels come within 7 days; expedited decisions within 72 hours. A letter from your prescriber that directly addresses the plan’s stated reason for denial does more than any other document to move an appeal forward. Keep copies of everything, and ask for a fast appeal if you need the medication soon.¹⁸

Help Paying for Prolia on Medicare

Amgen’s commercial copay program for Prolia generally does not apply to people on Medicare.⁸ Several other options can bring your costs down:

Extra Help, the federal Low-Income Subsidy for Part D, pays premiums up to a benchmark, reduces or eliminates copays, and waives the late enrollment penalty. In 2026, individuals with monthly income up to $2,015 ($2,725 for couples) and limited assets may qualify; people on Medicaid, SSI, or a Medicare Savings Program qualify automatically. You can apply through Social Security online or by calling 1-800-772-1213.¹⁹²⁰
A Medigap policy can pick up your 20% Part B coinsurance, which for many beneficiaries brings the cost of a doctor-administered Prolia injection down to nothing beyond their premium.⁸
The Amgen Safety Net Foundation, an independent charity, provides medication at no cost to qualifying patients, including Medicare beneficiaries with an affordability gap who do not have access to Extra Help or copay foundation funding. Eligibility is income-based, with 2026 limits starting at $47,880 for a one-person household.²¹

1
CMS.gov. Medicare Coverage Database – Billing and Coding Article A52399
2
CMS.gov. Medicare Coverage Database – Self-Administered Drug Exclusion List
3
Prolia HCP. Medical Benefit for Prolia
4
HealthRx. Denosumab Cost in Maryland
5
Palmetto GBA. Denosumab Billing and Coding – Drugs and Biologicals
6
Medicare.gov. Osteoporosis Drugs
7
Prolia HCP. Pharmacy Benefit for Prolia
8
Prolia. Paying for Prolia
9
KFF. Changes to Medicare Part D in 2024 and 2025 Under the Inflation Reduction Act
10
UnitedHealthcare. Part D Changes
11
JAMA Health Forum. Medicare Prescription Payment Plan
12
Blue Shield of California. Denosumab Medicare Part B Provider Policy
13
UnitedHealthcare Provider. Prolia and Xgeva Replaced by Biosimilars
14
Independence Blue Cross. Important Biosimilar Updates for Medicare Advantage Formularies
15
Priority Health. 2026 Formulary Changes
16
CVS Health. CVS Health Helps Customers Accelerate Biosimilar Adoption Through Formulary Changes
17
CMS.gov. Part D Exceptions
18
Medicare Interactive. Introduction to Part D Appeals
19
Medicare Interactive. Extra Help Basics
20
SSA. Part D Extra Help
21
Amgen Safety Net Foundation. Eligibility