At least 21 health systems terminated or declined to renew Medicare Advantage contracts in 2026, on Becker's Hospital Review's running tracker. Separately, a Johns Hopkins study in JAMA found 2.9 million MA enrollees forced to find new coverage for 2026, a 10% forced disenrollment rate against a 1% average from 2018 through 2024. The network map and the enrollment map moved at the same time, and both land in the 2027 bid.
Key Takeaways
- $450 million in unpaid claims for care already delivered is what Mount Sinai cited publicly during its Anthem dispute, which took roughly 200,000 members out of network for three and a half months before an April 13, 2026 agreement.
- 303 counties lost a major carrier as UnitedHealthcare exited 109 counties and one state and Humana exited 194 counties and three states, dropping from 89% to 85% of U.S. counties.
- 9,797 to 7,770 diagnostic codes is the V28 reduction now at full weight, projected to compress average MA risk scores 3.12% and save the Medicare Trust Fund roughly $11 billion.
- 72% of inactive providers listed in MA and Medicaid managed care behavioral health directories should not have been there, in a 2025 HHS Office of Inspector General review.
Who Left, and What They Said About Why
The exits reach the recognizable end of academic medicine and specialty care, and they are spread across every major carrier rather than concentrated at one.
| Health System | Insurer(s) Dropped | Effective Date | Scope |
|---|---|---|---|
| Mayo Clinic | UnitedHealthcare, Humana | January 1, 2026 | MN, WI, IA locations; individual and DSNP plans |
| Mount Sinai Health System | Anthem (Elevance) | January 1, 2026 | 9,000+ physicians; ~200K affected members |
| UNC Health | Humana, WellCare (Centene), HCSC | January 2026 | Multiple MA plans across North Carolina |
| Providence Clinical Network | UnitedHealthcare | January 1, 2026 | 15 hospitals across California markets |
| Lehigh Valley Health Network | UnitedHealthcare | January 25, 2026 | Individual, I-SNP, D-SNP, and Group Retiree plans |
| Moffitt Cancer Center | Aetna (CVS), Humana | Dec 2025 / July 2026 | Cancer center; specialty access in Tampa market |
The stated reasons are consistent. Prior authorization friction leads: denials of care the system considered medically necessary, delayed payment, and administrative burden on physicians. Mount Sinai put a number on its side of it at more than $450 million in unpaid claims for care already delivered. Providence's chief executive called for a Medicare Advantage reset.
Humana's answer names the other half of the same arithmetic: provider reimbursement demands significantly above Original Medicare rates, which the plan argues reach beneficiaries as premium. Both descriptions can be accurate at once. MA payment is constrained by CMS benchmarks and V28 risk score compression while provider cost inflation is not, and the contract is where the two meet.
Mount Sinai and Anthem settled on April 13, 2026 and restored in-network access. The three and a half months in between still happened, across roughly 200,000 members, through flu season and ongoing chronic disease management.
The Selection Runs One Way and the Coding Runs the Other
Forced disenrollment at this scale changes the composition of the sending plan and the receiving plan on the same date. KFF counted 2.6 million individual MA-PD enrollees terminated at the end of 2025, 13% of that segment; Highmark Health alone terminated plans covering 148,000 enrollees, 44% of its individual MA-PD book.
Who moves is not random. Members with active oncology treatment or multi-condition management are the ones a network exit binds hardest, and they are the ones who switch to preserve provider access rather than accepting a default. The passive member stays where they are assigned. The receiving plan therefore acquires a cohort selected on care intensity, and its bid assumes an average new enrollee.
Risk adjustment does not fully catch this. V28 captures diagnosed conditions, and the selection is on treatment relationships rather than on codes.
The second effect works the opposite direction and compounds the first. Coding continuity depends on the encounter happening. A member whose annual comprehensive exam slips from the first quarter to the third because their physician left the network may have chronic conditions fall outside the risk adjustment submission window, which lowers the plan's risk score with no change in the member's health.
Set that against the bid arithmetic. CMS projects risk scores rising 2.45% in 2027 and an effective payment increase of about 2.48%, against medical cost trend of 6% to 8% in many markets. That gap is the bid before any disruption adjustment. A plan carrying material network turnover is projecting revenue off a national risk score trend that assumes stable provider relationships it does not have, while absorbing a transferred cohort priced at the segment average.
The carrier footprints show how differently that lands. UnitedHealthcare shed roughly 930,000 MA members while Humana gained 1.2 million; Elevance and Centene expanded county coverage into the vacated markets. The average beneficiary still chooses among plans from eight firms, unchanged for two years, which is exactly the statistic that cannot see the 303 counties.
The Adequacy Standard Measures a Different Moment
CMS evaluates network adequacy at application and renewal, using time-and-distance standards that ask whether 90% of beneficiaries in a county can reach one provider in each required specialty. It does not measure active networks against those criteria afterward.
GAO-15-710 documented the consequence: because provider composition changes continuously through terminations, relocations and closures, CMS cannot assure that a network stays adequate without collecting compliance evidence on a regular basis. Between 2016 and 2022 the agency sent enforcement letters to five insurers over seven plans that failed network adequacy requirements.
The timing is the whole problem. A network that cleared the distance standard in September can carry significant gaps by January if a health system terminates during open enrollment, and the beneficiary chose the plan from the published directory in between.
Directory accuracy is where that gets worse rather than better. The OIG's 2025 behavioral health review found 72% of inactive listed providers should not have been in the directory at all: listed where they no longer practiced, at closed facilities, or in networks they had formally exited. Ghost listings inflate apparent network size, which lets a plan clear the adequacy standard on paper while access fails in practice.
The CY2026 final rule requires updates within 30 days of the organization becoming aware of a change, plus standardized submissions to Medicare Plan Finder and annual accuracy attestations. It is a real improvement with two openings left in it. Thirty days of stale data is long enough to miss a specialist appointment, and the obligation attaches to what the plan is aware of, which does not require it to look.
So the actuary pricing 2027 is adjusting for a disruption the compliance framework is not built to observe, using base period experience from 2025 and early 2026 that contains the emergency utilization, duplicated diagnostics and deferred procedures the disruption itself produced.
Further Reading
- Medicare Advantage Plan Exits Force 3 Million to Switch in 2026: The JAMA study quantifying forced disenrollment rates, carrier exit patterns, and the actuarial implications of MA enrollment volatility at scale.
- CMS Prior Auth Metrics Go Public: Denial Rates and Actuarial Pricing Impact: How CMS-0057-F transparency requirements expose plan-level variation in denial rates, and the five channels through which prior auth reform affects 2027 rate filings.
- V28 Risk Model Goes Full-Weight, Compressing MA Risk Scores by $11 Billion: The risk adjustment model transition that compounds the financial pressure driving provider exits, with analysis of coding continuity requirements and bid-level modeling.
- CMS Star Ratings Shift to 65% Clinical Weight in 2027: How the measure reweighting toward clinical outcomes raises the stakes for network adequacy, particularly in behavioral health specialties where provider exits create the largest access gaps.
- Medicare Advantage Premiums Fall While Benefits Shrink: KFF Spotlight analysis showing the benefit erosion trend that accompanies network narrowing, with actuarial walkthrough of Part C bid mechanics and rebate allocation trade-offs.