Medicare is one of the largest sources of prescription drug spending in the United States, driven by a combination of self-administered drugs (Part D) and physician-administered drugs (Part B). Medicare directly pays for some drugs under Part B Fee-for-Service (FFS), also known as Original Medicare; other Part B drug costs are covered by outside payers through Medicare Advantage (MA), using funds provided by the Centers for Medicare & Medicaid Services (CMS).1 Life sciences companies may treat Original Medicare and MA as interchangeable channels because both are built on Medicare’s core benefits: hospital coverage (Part A) and medical coverage (Part B). However, this core similarity masks meaningful differences around access to healthcare providers, coverage of services, and patient out-of-pocket (OOP) costs. These nuances can shape patient and provider experience and access.
As Part B drug spending continues to grow—especially in oncology, ophthalmology, and rheumatology2—it is important that life sciences companies understand Original Medicare and MA as distinct systems rather than a single channel to optimize both patient and provider experiences with physician-administered products. Positive experiences are essential to improving quality of care and driving initial uptake, as well as continued use of innovative, physician-administered medicines. Negative perceptions can arise when initiating patients on therapy becomes more timely or costly than anticipated, underscoring the need for brand teams to identify, define, and understand sources of friction, especially those that differ by a patient’s Part B coverage (Original Medicare vs. MA). Plan design features and utilization management considerations unique to each program can influence access, cost exposure, and administrative workload for providers. Understanding the key differences between Original Medicare and MA can help ensure clear messaging on what to expect when initiating patients on therapy across sources of coverage.
What are the two paths through Medicare? Understanding the differences between Original Medicare and Medicare Advantage
Medicare beneficiaries can receive coverage via two primary structures: Original Medicare (Parts A and B) and Medicare Advantage.
Original Medicare (Parts A and B)
Original Medicare uses an FFS model and includes Part A (hospital insurance) and Part B (medical services insurance); it does not cover outpatient prescription drug coverage, which is available through a separate Part D plan:3
- Part A covers inpatient hospital stays, skilled nursing, and hospice
- Part B covers doctor visits, outpatient care (including physician-administered outpatient prescription drugs and biologicals), and durable medical equipment
In 2026, approximately 45% of all people (29 million individuals) with Medicare Part A and Part B were enrolled in Original Medicare.4
MA (Part C)
MA plans are offered by private insurers that administer Medicare benefits through managed care structures3:
- MA plans must cover all services provided by Original Medicare (Part A and B) and may include integrated drug coverage (Part D)
- MA plans may also have supplemental benefits, including dental, vision, hearing, and/or fitness, as well as reduced cost sharing, and lower OOP limits
MA enrollees accounted for over half of all Medicare beneficiaries with Part A and Part B in 2026 (55%, or 35 million individuals).4
Key access differences across Original Medicare Part B and MA
Several structural differences between Original Medicare Part B and MA can influence how patients access treatment.
Access to specialists and networks
One of the most visible differences between the programs is provider choice. Original Medicare Part B coverage allows patients to see any physician or hospital nationwide that accepts Medicare.5 In contrast, MA plans may use provider networks, meaning patients may need to receive care within the plan’s specified network and service area. Additionally, some MA plans may require referrals before patients can see specialists.5
For therapies that depend on access to specialty providers or centers of excellence, network design and utilization management in MA can influence:
- Access to treatment
- Prompt availability of care
- Costs incurred to see out-of-network providers
OOP cost exposure
OOP cost exposure also differs across the two programs. Under Original Medicare Part B, patients typically pay 20% coinsurance for covered services after meeting the deductible threshold.5 Patients in Original Medicare do not have a maximum out-of-pocket (MOOP) limit and may therefore remain exposed to high-cost OOP expenses for the rest of the year. Some patients may have supplemental coverage, such as Medigap or Medicaid, to help offset these costs.5 In 2023, most beneficiaries (87%) with Original Medicare had some form of additional coverage that supplements Medicare benefits, but 3.5 million beneficiaries (13%) lacked additional coverage, leaving them at risk of facing high OOP costs for care covered by medical benefits.6
Conversely, MA plans have varying OOP costs, but these plans have MOOP limits for covered services, which can mitigate patient cost exposure once the limit is reached.5 In 2026, the MOOP for MA is $9,250 for approved services, but plans can set lower limits if they wish.7 A recent Milliman white paper looked at the average in-network medical MOOP for MA Part D non-special needs plans (non-SNPs) in 2025 and 2026 and found that the in-network MOOP for preferred provider organization (PPO) products increased from 2025 to 2026.8
For life sciences companies, understanding the mix of coverage with Original Medicare (including how many patients have supplemental coverage) and MA (including MOOP) informs OOP costs and may impact:
- Patient initiation rates
- Demand for financial assistance programs
- Adherence to treatment
Prior authorization and utilization management
Another major distinction involves utilization management. In Original Medicare, patients must meet medical necessity criteria, defined through a National Coverage Determination (NCD) established by CMS or a Local Coverage Determination (LCD) developed by Medicare Administrative Contractors (MACs).5 Conversely, although MA plans must follow NCDs and LCDs where they exist, plans can create their own coverage criteria based on widely used treatment guidelines or clinical literature.9,10
An Original Medicare prior authorization program currently is in the pilot stage, but it largely does not apply to Part B physician-administered products.11 MA plans may require prior authorization for certain services, treatments, or supplies before coverage is approved. In addition to prior authorization, MA plans can also implement step therapy, where patients try and fail cost-effective or generic products before progressing to more advanced therapies.12
MA requirements can introduce administrative steps that influence:
- General access to therapy and time to treatment
- Provider prescribing behaviors
- Patient experience navigating treatment access
For therapies requiring rapid initiation or specialized diagnostics, these coverage differences can have implications for care delivery and operationalization.
Medicare considerations for life sciences strategy
With the increasing drug spend in Part B and a continually changing environment, life sciences companies should recognize that beneficiary access and experience cannot have one-size-fits-all approaches, and that coverage alone does not guarantee patient access. Instead, the path from diagnosis to treatment is shaped by other nonclinical factors, including a patient’s insurance structure, provider network, and plan management policies.
Understanding these dynamics allows life sciences companies to improve timely access to therapies by:
- Anticipating access barriers for patients and providers
- Gathering insight into patient OOP costs to help inform effective patient support programs
- Equipping providers with realistic expectations about coverage pathways
As the number of individuals eligible for Medicare grows and MA enrollment continues to increase, considering these differentiators can inform several strategic priorities for life sciences companies.13
Market access strategy
Manufacturers should consider both national Medicare policy and plan-level management practices when evaluating coverage environments
Medication affordability
Understanding Medicare beneficiary patient mix and true OOP costs can aid in managing expectations with providers and patients around affordability
Provider engagement
Physicians treating MA beneficiaries may face different utilization management requirements than those treating Original Medicare beneficiaries
Patient support design
Patient support programs and educational materials may need to reflect the distinct cost-sharing and authorization structures patients encounter between programs
Forecasting and market planning
Although a growing share of Medicare beneficiaries is enrolled in MA, the growth rate of increase in enrollment is slowing in comparison to past years, making payer-driven access dynamics increasingly important in determining treatment uptake4
Conclusion: Why understanding Medicare plan differences is vital to market access strategy at life sciences companies
Not all Medicare Part B beneficiaries experience coverage in the same way. Whether a patient is covered with Original Medicare or with an MA plan can shape their access to specialists, their exposure to OOP costs, and the administrative steps required before treatment begins. For life sciences companies focused on improving patient access, understanding these differences is foundational to effective market access strategy in the Medicare landscape.
1 Bunch, L.N., & Ketema, H. (2025, September, 60–288). Health insurance coverage in the United States: 2024. U.S. Census Bureau. Retrieved June 29, 2026, from https://www2.census.gov/library/publications/2025/demo/p60-288.pdf.
2 Prime Therapeutics. (2025, July). Medical pharmacy trend report. Retrieved June 29, 2026, from https://issuu.com/primetherapeutics/docs/2025_medical_pharmacy_trend_report.
3 Medicare.gov. (n.d.). Your coverage options. Retrieved June 29, 2026, from https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/your-coverage-options.
4 Freed, M., Biniek, J.F., Damico, A., & Neuman, T. (2026, June 5). Medicare Advantage in 2026: Enrollment update and key trends. KFF. Retrieved June 29, 2026, from https://www.kff.org/medicare/medicare-advantage-in-2026-enrollment-update-and-key-trends/.
5 Medicare.gov. (n.d.). Compare Original Medicare & Medicare Advantage. Retrieved June 29, 2026, from https://www.medicare.gov/basics/get-started-with-medicare/get-more-coverage/your-coverage-options/compare-original-medicare-medicare-advantage.
6 Ocheing, N., Cubanski, J., & Neuman, T. (2025, December 19). A snapshot of sources of coverage among Medicare beneficiaries. KFF. Retrieved June 29, 2026, from https://www.kff.org/medicare/a-snapshot-of-sources-of-coverage-among-medicare-beneficiaries/.
7 National Council on Aging. (2026, June 25). What you’ll pay in out-of-pocket Medicare costs in 2026. Retrieved June 29, 2026, from https://www.ncoa.org/article/what-you-will-pay-in-out-of-pocket-medicare-costs-in-2026/.
8 Nelson, P., Friedman, J., & Timm, M. (2026, February 16). Medicare Advantage under pressure: How MA-PD plans are rethinking $0 premium PPO offerings in 2026. Milliman. Retrieved June 29, 2026, from https://www.milliman.com/en/insight/ma-pd-plans-rethinking-0-premium-ppo-2026.
9 CMS. (2023, April 5). 2024 Medicare Advantage and Part D final rule (CMS-4201-F) (Fact sheet). Retrieved June 29, 2026, from https://www.cms.gov/newsroom/fact-sheets/2024-medicare-advantage-and-part-d-final-rule-cms-4201-f.
10 Tucker, C. (2023, May 3). CMS final rule: Changes to the Medicare Advantage program. Ensemble Health Partners. Retrieved June 29, 2026, from https://www.ensemblehp.com/blog/cms-final-rule-changes-to-the-medicare-advantage-program/.
11 American Hospital Association. (2025, June 27). CMS announces new prior authorization program pilot. Retrieved June 29, 2026, from https://www.aha.org/news/headline/2025-06-27-cms-announces-new-prior-authorization-program-pilot.
12 CMS. (2018, August 7). Medicare Advantage prior authorization and step therapy for Part B drugs (Fact sheet). Retrieved June 29, 2026, from https://www.cms.gov/newsroom/fact-sheets/medicare-advantage-prior-authorization-step-therapy-part-b-drugs.
13 Biniek, J.F., Freed, M., Ochieng, N., & Neuman, T. (2026, February 23). Medicare Advantage enrollment grew by about 1 million people, mainly due to special needs plans. KFF. Retrieved June 29, 2026, from https://www.kff.org/medicare/medicare-advantage-enrollment-grew-by-about-1-million-people-mainly-due-to-special-needs-plans/.