INSIGHTS: Medicare Advantage Provider Networks
Medicare Advantage Provider Networks:
What the Data Shows Plans Are Getting Wrong
What the Data Shows Plans Are Getting Wrong
Medicare Advantage plans are legally required to maintain provider networks sufficient to serve their enrolled populations. The data shows they are structurally compliant in most cases and operationally insufficient in many. KFF analysis found MA enrollees had access to just under half the physicians available to Original Medicare beneficiaries. CMS enforcement of network adequacy violations has been nearly absent for a decade. MedPAC confirmed in 2024 that CMS has never imposed civil money penalties for network adequacy non-compliance. This analysis examines what the evidence shows about the gap between MA network adequacy standards and the access reality they are supposed to guarantee, and what compliance leaders need to understand before CMS changes its enforcement posture.
48%
of Physicians Accessible in MA vs. Original Medicare
A 2022 KFF analysis found that Medicare Advantage enrollees had access to just under half (48%) of all physicians available to Original Medicare beneficiaries in their area. The one-fifth of MA enrollees in the narrowest networks had access to only about one-third. Plans with the broadest networks reached two-thirds. The average MA plan gives enrollees access to roughly half the physician choice that Original Medicare does.
KFF: MA Physician Access Analysis (2022)
5
Network Violation Letters in 10 Years, 0 CMPs Ever Imposed
CMS sent just 5 network adequacy violation letters to insurers from 2016 to 2022, covering 7 plans. MedPAC confirmed in June 2024 that CMS has the authority to impose civil money penalties for network adequacy non-compliance but has never done so. The enforcement gap between the standard and its consequence is total.
KFF Health News: CMS Network Adequacy Enforcement (2024)
58-59%
Physician Access Rate at Largest MA Carriers
The average Blue Cross plan offers access to 59% of physicians available to Original Medicare enrollees. UnitedHealthcare plans reach approximately 58%. Even the largest plans with the broadest networks give enrollees access to fewer than 6 in 10 physicians that Original Medicare members can see, structurally compliant, but substantially narrower than the traditional programme.
GoodRx: Medicare Advantage Network Limits (2026)
Insight Summary
- MA enrollees had access to just 48% of physicians available to Original Medicare in 2022, a figure that has not materially improved since KFF first measured it, and that varies from one-third to two-thirds depending on which quintile of network breadth the plan falls into.
- CMS enforced network adequacy standards with only 5 violation letters over a decade, covering 7 plans, and has never imposed a civil money penalty for network non-compliance, despite having explicit authority to do so under 42 CFR 422.752.
- The structural compliance gap and the enforcement gap are related: plans that know violations generate letters but not penalties have less operational pressure to close the access gap than the regulatory framework implies.
- Beginning with CY2024, CMS moved network adequacy assessment to the application stage, requiring plans to demonstrate adequacy before approval rather than after, which is the first meaningful tightening of the enforcement posture in the data record.
- Provider directory accuracy is a separate and concurrent compliance obligation: phantom physicians, providers listed as in-network who have retired, left, or closed their panels, are a documented systemic problem that makes the 48% figure an overestimate of actual accessible physician supply.
- The compliance implication for plan administrators is forward-looking: the enforcement environment that produced zero CMPs in a decade is changing, and plans whose network infrastructure was built for the prior environment are carrying structural risk into an environment where CMS has signalled intent to use application denial more aggressively.
Key Insight
Medicare Advantage provider networks are structurally compliant but operationally narrow, and the enforcement gap that allowed this to persist for a decade is narrowing at exactly the moment plans are least prepared for it.
A plan that meets every CMS network adequacy benchmark on paper while its enrolled members cannot get appointments with listed providers has satisfied the regulatory standard without delivering the access the standard was designed to guarantee. That gap, between structural compliance and operational access, has existed for years without meaningful enforcement consequences. CMS’s move to application-stage network assessment and its signalled intent to use application denial more aggressively represents the first structural change to the enforcement dynamic. Plans that built networks for the prior enforcement environment are now building for a different one.
What the Data Shows
DATA
KFF’s 2022 analysis of MD-PPAS federal physician data found that Medicare Advantage enrollees had access to just under half (48%) of all physicians available to Original Medicare beneficiaries in their area. Among the one-fifth of MA enrollees in plans with the narrowest networks, in-network access fell to approximately one-third of available physicians. The one-fifth in plans with the broadest networks reached over two-thirds. Hospital-based physicians were least likely to participate in MA networks, only 21% were included in MA directories, compared to their much higher Original Medicare participation rate. Source: KFF: Medicare Advantage Enrollees Have Access to About Half of Physicians (2022)
INTERPRETATION
A 48% physician access rate means MA enrollees are choosing their plan from a coverage universe that is, on average, half the size of what they would have in Original Medicare. This is not a marginal narrowing, it is a structural reduction in access that is the default state of the MA market, not an outlier. The 21% hospital-based physician inclusion rate is the most operationally significant figure: it means that when an MA member is hospitalised, the physicians treating them in the hospital are overwhelmingly not in their plan’s network, creating automatic out-of-network exposure that most enrollees do not understand at the time of enrollment.
WHY IT MATTERS
For plan administrators, the 48% figure is a benchmark against which to assess their own network breadth, and a baseline for understanding member grievances about provider access. Plans whose physician access rate falls significantly below 48% are at elevated risk of member access complaints, network adequacy findings in programme audits, and application denial for service area expansions. Plans whose rate is near or above the market average are less exposed but must still manage the hospital-based physician gap separately, since it generates out-of-network billing disputes that surface as member complaints regardless of overall network breadth.
DATA
A KFF Health News FOIA investigation found that CMS sent only 5 network adequacy violation letters to insurers from 2016 to 2022, covering 7 plans with documented network deficiencies, including one case where five hospitals and 13 nursing homes left a single insurer’s network in one county alone. The June 2024 MedPAC report to Congress confirmed that “CMS has the authority to impose intermediate sanctions or civil monetary penalties for noncompliance with network adequacy standards, but it has never done so.” CMS declined to explain to KFF Health News why it found so few plans with violations over the decade. Source: KFF Health News: CMS Network Adequacy Enforcement (2024)
INTERPRETATION
Five violation letters over a decade, covering a programme serving tens of millions of members across hundreds of plan contracts, is not a low enforcement rate. It is effectively no enforcement. The MedPAC finding that CMPs have never been imposed despite explicit statutory authority is the clearest possible signal that the regulatory framework for network adequacy existed as a paper standard during this period, not an operational one. The reason this matters now is that it did not change by accident, it changed because CMS moved network adequacy assessment to the application stage in CY2024, which is a structural shift in where enforcement pressure is applied, not just a change in intent.
WHY IT MATTERS
Plans that have managed network adequacy compliance in the prior enforcement environment, where violations generated letters but not penalties, are now managing it in an environment where application denial is the primary enforcement consequence. The operational question is whether the same network infrastructure that passed annual attestations under the prior model will pass application-stage review under the new one. For plans considering service area expansions, the answer requires demonstrating network adequacy before the application is approved, not remedying it afterward.
DATA
Provider directory inaccuracy is a documented, systemic problem in Medicare Advantage. KFF noted that private health plan network directories frequently include significant numbers of “phantom” physicians, providers listed as in-network who have retired, left practice, or are otherwise no longer providing care. The MD-PPAS dataset KFF used to measure actual physician access excludes these phantom listings, meaning the 48% figure is based on physicians who actually submitted at least one Medicare Part B claim in the year, a more conservative and accurate count than directory-based measures. A CAP analysis noted CMS has identified provider directory accuracy as a data gap requiring regulatory attention, separate from and concurrent with the network adequacy attestation requirement. Source: Center for American Progress: 6 MA Data Gaps CMS Must Fill (2024)
INTERPRETATION
If the 48% figure is based on actively practicing physicians and the plan’s own directory includes phantom listings, the directory-based access figure the plan reports to CMS is higher than the operational access figure members actually experience. This means network adequacy attestations that rely on directory counts without verification against actual practice activity are systematically overstating the accessible physician supply, which is the most likely explanation for why plan-reported adequacy figures consistently exceed what member access complaints would predict.
WHY IT MATTERS
Plans that attest to network adequacy based on directory counts without verifying that listed providers are actively accepting new MA patients are building their compliance posture on data they have not validated. Provider directory accuracy is a separate CMS compliance requirement with its own audit track, it is not absorbed by network adequacy attestation. A plan that passes the network adequacy standard while listing phantom physicians in its directory is non-compliant on provider directory accuracy regardless of whether its network adequacy numbers are correct.
What Is Driving the Trend: Why Network Adequacy Gaps Persist
The standard measures network structure, not operational access
CMS network adequacy standards assess provider-to-member ratios, time and distance, and specialty availability, all of which measure what the network looks like on paper. They do not measure whether a member can actually schedule an appointment with a listed provider. A plan can satisfy every adequacy benchmark while its members encounter closed panels and providers who stopped accepting new MA patients months ago. CMS acknowledged this gap in its 2025 regulatory cycle but did not finalise a requirement for plans to verify operational availability. Source: Neolytix: CMS Network Adequacy vs. Operational Access (2025)
Provider directory updates lag provider network changes
CMS requires online provider directory updates within 30 business days of a change notification. In practice, providers leave networks, close panels, retire, or relocate without notifying the plan, and the plan’s directory reflects this change only when a member or the plan discovers it, often through a failed appointment attempt. The phantom physician problem is not a deliberate misrepresentation: it is the structural result of a directory update process that depends on providers initiating change notifications they have no operational incentive to file promptly. Plans that rely on passive update processes generate stale directories regardless of their compliance intent.
MA payment rates create differential participation incentives
Physicians participate in MA networks based on a calculation that weighs MA payment rates against Original Medicare rates and against their administrative burden from prior authorisation requirements. When MA payment rates are lower than Original Medicare rates for the same services, or when a plan’s prior authorisation frequency creates significant administrative cost, physicians who accept Medicare may nonetheless decline to participate in specific MA plans. This creates a structural participation gap that no amount of network building can fully close without addressing the underlying payment and administrative burden dynamic. Source: GoodRx: Medicare Advantage Network Limits (2026)
Application-stage assessment shifts the enforcement timeline but not the infrastructure
CMS’s CY2024 move to assess network adequacy at the application stage changes when compliance is evaluated, but it does not change what plans must demonstrate or how they must build their networks. Plans that previously relied on post-approval remediation to close network gaps must now close those gaps before the application is submitted. This is a meaningful tightening, but it creates compliance risk for plans that have historically passed annual attestations without verifying operational access, because the application-stage review is based on the same standards that the attestations were based on, applied earlier and with application denial as the consequence of failure. Source: Epstein Becker: MA Network Adequacy Changes for 2024
What This Means for Compliance and Network Leaders
Measure your physician access rate against the 48% market benchmark
The KFF 48% figure gives plan administrators a market-level benchmark for physician access breadth. Plans whose network access rate falls significantly below 48% relative to Original Medicare are at elevated risk on two fronts: member access complaints that surface in programme audits, and network adequacy findings on application review. Plans should assess their own physician access rate against this benchmark using the same methodology, active practitioners with at least one MA claim, not directory headcounts, and close the gap before the application review creates deadline pressure.
Treat provider directory accuracy as a concurrent compliance obligation, not a subset of network adequacy
CMS audits provider directory accuracy separately from network adequacy attestation. A plan that passes its network adequacy benchmark while listing phantom physicians fails the provider directory accuracy requirement. Active outreach programmes, systematic verification that listed providers are accepting new MA patients, with panel status updated within the 30-business-day requirement, are the only operational control that closes the phantom physician gap. Passive update processes that depend on providers self-reporting changes do not meet this standard in practice.
Address the hospital-based physician gap separately, it generates member complaints regardless of overall network adequacy
Hospital-based physicians, the intensivists, hospitalists, radiologists, anaesthesiologists, and pathologists that treat MA members during inpatient stays, participate in MA networks at only 21%. This means the majority of physicians a member encounters during a hospitalisation are out-of-network by default. Member complaints about unexpected out-of-network bills from hospital-based physicians are a predictable and preventable consequence of this gap. Plans with strong overall network adequacy figures but poor hospital-based physician coverage generate member access complaints that will not appear in their adequacy attestation and will appear in their grievance data.
Build network expansion plans on application-stage adequacy requirements, not post-approval remediation assumptions
Any plan considering expanding to a new county or service area must demonstrate network adequacy at the application stage, not after approval. This means provider contracting and network building must begin significantly before the application submission window. Plans that begin contracting after receiving approval, the prior practice, are building for an enforcement model that no longer applies. The application timeline for CY2026 and beyond requires working backward from CMS application deadlines to determine when provider contracting must be complete to support the application.
Medicare Advantage Provider Networks: What Plans Must Do
| Gap | Evidence | Required Action | Enforcement Risk |
|---|---|---|---|
| Physician access rate below market average | 48% market average; narrowest quintile at 33% | Benchmark own rate against 48%; identify specialty and geographic gaps; close before next application cycle | Application denial (HIGH from CY2024); programme audit finding (MODERATE) |
| Phantom physicians in directory | Documented systemic problem; 48% KFF figure based on active practitioners only | Active outreach to verify panel status; update within 30 business days; do not rely on passive provider-initiated change notifications | Provider directory accuracy finding (HIGH, audited separately from network adequacy) |
| Hospital-based physician coverage gap | Only 21% of hospital-based physicians in MA directories | Track hospital-based physician coverage separately; proactively notify members of out-of-network exposure during inpatient stays; include in member communications pre-enrollment | Member grievances (HIGH); surprise billing complaints (MODERATE); does not appear in standard adequacy attestation |
| Network expansion planned without pre-application contracting | CY2024 application-stage adequacy assessment requirement | Begin provider contracting for expansion counties well before application submission; demonstrate adequacy in the application, not in post-approval remediation | Application denial (HIGH, primary enforcement mechanism from CY2024) |
Executive Takeaway
For Network and Compliance Leaders
- Measure your plan’s physician access rate against the 48% market benchmark using active practitioner data, not directory headcounts, to identify your true network gap.
- Implement active outreach to verify panel status for all listed providers, not passive reliance on provider-initiated change notifications, to close the phantom physician gap before it becomes a directory accuracy audit finding.
- Track hospital-based physician coverage separately and include out-of-network inpatient physician exposure in pre-enrollment member communications, it will not appear in your network adequacy attestation and will appear in your grievance data.
- Build any service area expansion plan around application-stage adequacy demonstration, provider contracting must be complete before the application is submitted, not remedied after approval.
- Assess whether your network infrastructure was built for the prior enforcement environment (zero CMPs, post-approval remediation) or the current one (application denial, pre-approval demonstration). The two require different operational approaches.
Key Takeaways
Structural compliance and operational access are different things, the data shows MA networks satisfy the former and fall short on the latter
A 48% physician access rate means MA plans are, on average, structurally compliant with CMS standards and operationally providing enrollees with half the physician choice that Original Medicare offers. These two statements are simultaneously true. CMS standards were calibrated to a threshold that most plans can meet, not to a threshold that produces access equivalent to Original Medicare. Plans that optimise for regulatory compliance rather than member access will continue to produce the 48% figure, the phantom physician problem, and the hospital-based physician gap that generates the grievances that surface in programme audits.
The enforcement environment has structurally changed, plans built for the prior environment carry risk in the new one
A decade of near-absent CMS enforcement allowed plans to manage network adequacy as an attestation exercise rather than an operational standard. CMS’s move to application-stage assessment means that for service area expansions and new plan applications, network adequacy is now evaluated before approval rather than remediated after. Plans whose contracting timelines, directory management processes, and access verification systems were built for post-approval remediation need to restructure for pre-application demonstration. The same standard now applies at a different point in the timeline, and with a different consequence for failure.
Provider directory accuracy is not a subset of network adequacy, it is a parallel and separately audited compliance obligation
Plans that pass their network adequacy attestation while listing phantom physicians fail a separate CMS compliance requirement. Provider directory accuracy is audited independently and has its own update timeline obligations. The operational implication is that network adequacy management and provider directory management are two distinct compliance programmes that must both function correctly, a plan cannot satisfy one by satisfying the other. The phantom physician problem will not be resolved by network building. It will only be resolved by active outreach to verify panel status and timely directory updates when providers close their panels or leave the network.
Frequently Asked Questions
How do Medicare Advantage provider networks compare to Original Medicare in physician access?
KFF’s 2022 analysis found MA enrollees had access to just under half (48%) of all physicians available to Original Medicare beneficiaries in their area. The one-fifth in the narrowest networks had access to about one-third; the one-fifth in the broadest had access to over two-thirds. The average Blue Cross plan reaches 59% of physicians available to Original Medicare; the average UnitedHealthcare plan reaches approximately 58%. Hospital-based physicians, who treat MA members during inpatient stays, were the least likely to participate, with only 21% included in MA directories. Source: KFF: MA Physician Access Analysis (2022)
Has CMS ever penalised a Medicare Advantage plan for network adequacy violations?
No. CMS has the authority to impose civil money penalties for network adequacy non-compliance under 42 CFR 422.752 but has never done so. A 2024 MedPAC report to Congress explicitly confirmed this. From 2016 to 2022, CMS sent only 5 violation letters to insurers covering 7 plans, including one case where 5 hospitals and 13 nursing homes left an insurer’s network in a single county. The standard enforcement consequence has been a violation letter with a warning that marketing and enrollment freezes or plan closure could follow, not financial penalties. Source: KFF Health News: CMS Network Adequacy Enforcement (2024)
What are phantom physicians in Medicare Advantage provider directories?
Phantom physicians are providers listed in a Medicare Advantage plan’s directory as in-network who are not actually available to patients, because they have retired, relocated, closed their panel to new patients, or left the network without the plan being notified. Provider directory inaccuracy from phantom listings is a documented, systemic problem in MA. It means that when a member looks up a physician in the plan’s directory, they may find providers who cannot see them. KFF’s methodology for measuring MA physician access specifically excluded phantom listings by using only physicians who submitted at least one Medicare Part B claim in the year, which is why their 48% figure represents actual accessible physicians rather than directory-inflated counts.
What changed about Medicare Advantage network adequacy assessment in CY2024?
Beginning with CY2024 applications, CMS restructured network adequacy assessment so that MA applicants must now demonstrate network adequacy during the application review process, before receiving approval, rather than demonstrating it post-approval and remedying deficiencies afterward. This is a fundamental shift: under the prior model, plans could receive approval and then have time to cure network gaps. Under the new model, application denial is the consequence of inadequate networks at the time of application. For service area expansions, this means provider contracting must be substantially complete before the application is submitted. Source: Epstein Becker: MA Network Adequacy Changes for CY2024
Why do so few hospital-based physicians participate in Medicare Advantage networks?
Hospital-based physicians, hospitalists, intensivists, radiologists, anaesthesiologists, pathologists, are often employed by hospitals or physician groups under contractual arrangements that do not automatically include all payer networks. Their services during inpatient stays may be covered regardless of network status under certain plan designs, reducing the financial incentive for both the physician and the plan to negotiate a specific network contract. KFF found only 21% of hospital-based physicians were included in MA directories, compared to much higher participation rates for outpatient physicians. The practical result is that MA members who are hospitalised are likely to be treated by out-of-network physicians even at in-network hospitals, a source of unexpected costs and member complaints that does not appear in overall network adequacy attestations.
What is the difference between network adequacy and provider directory accuracy in Medicare Advantage compliance?
Network adequacy under 42 CFR 422.112 measures whether a plan has a sufficient number and type of contracted providers across its service area to meet time, distance, and provider-to-member ratio standards. Provider directory accuracy is a separate CMS compliance requirement, online directories must be updated within 30 business days of a change notification and must accurately reflect which providers are currently in the network and accepting new patients. A plan can pass its network adequacy attestation (sufficient contracted provider count) while failing provider directory accuracy (stale listings that do not reflect the current state of those provider relationships). CMS audits both requirements, and failure on provider directory accuracy does not benefit from passing network adequacy.
How does Medicare Advantage provider network breadth affect Star Ratings?
Network adequacy as a standalone measure does not directly generate a Star Ratings score. However, network-related member access failures cascade into Star Ratings through measures that are scored: member complaints about getting needed care (which surface from network access failures), grievance rates (which capture member complaints about provider access), and the CAHPS survey questions about getting care quickly and getting needed care. Plans with structurally adequate networks that are operationally inaccessible, due to phantom listings or closed panels, will see these member experience measures decline, which directly affects Star Ratings scores in the access and member experience domains. Source: CMS: Part C and Part D Compliance and Star Ratings
Sources
Government and Policy Sources
- KFF: Medicare Advantage Enrollees Have Access to About Half of the Physicians Available to Traditional Medicare Beneficiaries (2022): primary source for the 48% physician access figure, the narrowest-quintile one-third and broadest-quintile two-thirds data, the 21% hospital-based physician participation rate, and the methodology of using MD-PPAS active practitioner data rather than directory headcounts to measure actual accessible physician supply.
- KFF Health News: Complaints About Gaps in Medicare Advantage Networks Are Common. Federal Enforcement Is Rare. (2024): FOIA-based investigation confirming only 5 network adequacy violation letters sent to 5 insurers covering 7 plans from 2016 to 2022; source for the Vitality Health Plan case where 5 hospitals and 13 nursing homes left one county’s network; and source for MedPAC’s June 2024 confirmation that CMS has never imposed civil money penalties for network adequacy non-compliance.
- CMS: Part C and Part D Compliance and Audits: authoritative source for network adequacy regulatory requirements under 42 CFR 422.112, provider directory accuracy obligations, and the programme audit protocols under which both are assessed.
- Center for American Progress: 6 Medicare Advantage Data Gaps That CMS Must Fill (2024): source for CAP’s identification of network adequacy and provider directory accuracy as separate and concurrent data gaps requiring independent regulatory attention; and source for the $83-127 billion CMS overpayment estimate for MA plans in 2024.
Industry Sources
- Epstein Becker Green: Medicare Advantage Provider Network Adequacy Regulatory Changes for 2024: analysis of CMS’s CY2024 application-stage network adequacy assessment requirement, the shift from post-approval remediation to pre-approval demonstration, and the implications for service area expansion planning timelines.
- GoodRx: How Do Medicare Advantage Network Limits Work? (2026): source for carrier-specific physician access rates (Blue Cross 59%, UnitedHealthcare 58%) and the structural context for why MA plans access fewer physicians than Original Medicare.
- Neolytix: Your Practice Meets CMS Network Adequacy Rules, But Patients Still Cannot Get Appointments (2025): source for the structural gap between CMS network adequacy attestations and operational provider availability, and CMS’s decision not to finalise a requirement for plans to verify operational access as part of adequacy assessment.
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