Trust layer

Methodology, sources & limitations

MedicareInsights is an independent, AI-driven analytics site that educates the industry with public CMS data. It is not affiliated with CMS or any carrier. Everything below is the complete source registry — the same records that power the provenance panel on every chart.

Status key

live refreshed automatically from the CMS API · static extract compiled from the named CMS file, automated pipeline pending · curated analyst-maintained editorial content · modeled MedicareInsights estimate — directional, never citable as CMS data.

Source registry

MA enrollment & penetration by state live

Source file: CMS Medicare Monthly Enrollment (data.cms.gov, public API)
Vintage: February 2026
Last updated: June 15, 2026
Cadence: Monthly (CMS publishes ~3 months in arrears)
Method: State-level rows pulled from the Medicare Monthly Enrollment API; MA share = MA_AND_OTH_BENES / TOT_BENES. Refreshed via automated pipeline from the CMS public API.
Limitations: Penetration here is share of all Medicare beneficiaries (Parts A and/or B), not the KFF eligible-only basis, which runs ~4pts higher.

National MA vs Original Medicare, 2010–2026 static extract

Source file: CMS Medicare Monthly Enrollment; CMS MA landscape files (historical)
Vintage: Plan year 2026 (Feb 2026 enrollment)
Last updated: June 15, 2026
Cadence: Monthly enrollment; annual landscape
Method: Year-end MA and Original Medicare enrollment in millions; premiums/MOOP are enrollment-weighted plan-year averages.
Limitations: Static extract pending automated pipeline. Premium/MOOP averages compiled from CMS landscape releases, not recomputed here.

County-level MA market snapshot (76 tracked counties) static extract

Source file: CMS MA Enrollment by State/County/Plan (CPSC monthly files)
Vintage: Plan year 2026, with 2023–2026 penetration history
Last updated: May 1, 2026
Cadence: Monthly (pipeline pending; currently a curated extract)
Method: Penetration, D-SNP share, carrier count and top carrier per county compiled from CPSC files for 76 high-signal counties.
Limitations: Covers 76 tracked counties, not all ~3,100. Velocity = simple YoY penetration point change.

Carrier footprint by state static extract

Source file: CMS monthly enrollment by contract (OEC), March 2026; CMS landscape files
Vintage: March 2026
Last updated: May 1, 2026
Cadence: Monthly (pipeline pending; currently a curated extract)
Method: Enrollment in thousands by carrier and state; plan counts, star rating of largest plan, premium/MOOP of flagship product.
Limitations: Curated for major carriers in key states; trend %s are YoY and carrier notes are analyst commentary, not CMS data.

Part D benefit parameters, CY2022–CY2026 static extract

Source file: CMS Part D benefit parameter announcements; IRA statutory provisions
Vintage: CY2026 final parameters
Last updated: April 7, 2026
Cadence: Annual (April announcement)
Method: Published standard deductible and IRA out-of-pocket cap by contract year; carrier deductible-waiver strategies compiled from public formulary filings.
Limitations: Waiver-strategy rows are compiled from public filings and may lag mid-year formulary changes.

Dual-eligible density by state static extract

Source file: CMS Medicare-Medicaid dual enrollment data (MMCO quarterly)
Vintage: 2025 Q4
Last updated: March 15, 2026
Cadence: Quarterly (pipeline pending; currently a curated extract)
Method: Duals as % of state Medicare population; D-SNP coverage % = share of duals in a county with ≥1 D-SNP available.
Limitations: State-level only; FIDE availability flag is binary and does not reflect county variation.

2026 plan exits and member migration static extract

Source file: CMS 2026 non-renewal notices; carrier investor disclosures
Vintage: Plan year 2026 (announced fall 2025)
Last updated: January 20, 2026
Cadence: Annual (non-renewals announced each fall)
Method: Terminated plan counts and affected membership from CMS crosswalk files; migration shares from January enrollment reconciliation.
Limitations: Migration percentages are early-year estimates; 'active shopping' share is directional.

Net benefit value (PMPM) vs 2022 baseline modeled

Source file: Modeled from CMS bid/landscape data — MedicareInsights estimate
Vintage: Plan years 2022–2026
Last updated: April 15, 2026
Cadence: Annual
Method: PMPM supplemental-benefit value modeled from landscape benefit files against a 2022 baseline. Directional estimate, not an actuarial figure.
Limitations: Modeled — do not cite as CMS data. Use for prioritization, not filings.

Star rating trajectory by carrier static extract

Source file: CMS MA Star Ratings (annual, published each October); CMS prior-auth reporting
Vintage: 2026 Star Ratings (published Oct 2025)
Last updated: February 10, 2026
Cadence: Annual (October)
Method: Enrollment-weighted average star rating for each carrier's contracts, one point per rating year from the official October release.
Limitations: Only annual October ratings are shown; CMS does not publish quarterly ratings.

Star measure-level erosion, top carriers static extract

Source file: CMS Star Ratings measure-level data (Part C & D performance files)
Vintage: 2022–2026 rating years
Last updated: February 10, 2026
Cadence: Annual (October)
Method: Five-year measure-score series for UHC, Humana, Aetna on high-weight measures; driver notes are analyst interpretation.
Limitations: Three carriers, selected high-weight measures only. Driver commentary is interpretation, not CMS data.

CMS policy developments curated

Source file: CMS.gov newsroom, Federal Register, CMS fact sheets (curated)
Vintage: Through July 2026
Last updated: July 1, 2026
Cadence: Ad hoc, reviewed monthly
Method: Analyst-curated summaries of CMS announcements with impact ratings.
Limitations: Curated selection, not a complete feed. Impact ratings are editorial.

Regulatory reference library curated

Source file: CMS Medicare Managed Care Manual (Pub. 100-16); IRA 2022; 2027 Advance Notice
Vintage: Current through 2027 Advance Notice (Feb 2026)
Last updated: February 15, 2026
Cadence: Updated on major rulemaking
Method: Plain-language chapter summaries with analyst TL;DRs.
Limitations: Summaries, not legal text. Always verify against the manual before compliance decisions.

SNP share of MA enrollment by state static extract

Source file: CMS SNP Comprehensive Report (monthly)
Vintage: February 2026
Last updated: May 1, 2026
Cadence: Monthly (pipeline pending; currently a curated extract)
Method: SNP, D-SNP, C-SNP, I-SNP enrollment as % of state MA enrollment.
Limitations: Rounded to whole percentages.

Growth runway index by state and county modeled

Source file: MedicareInsights index computed from CMS Medicare Monthly Enrollment and CPSC county extracts
Vintage: Plan year 2026 (Feb 2026 enrollment)
Last updated: July 17, 2026
Cadence: Recomputed on every enrollment ingest
Method: Runway score = penetration gap x velocity x market size, normalized so the top geography scores 100. Penetration gap is the distance to the highest penetration observed in the tracked set (revealed attainable ceiling). Velocity is the YoY penetration point change: actual for tracked counties, enrollment-weighted tracked-county average for their states, and the tracked-set median as a proxy for states with no tracked county. Market size is the Original Medicare base in millions. Geographies under 50% penetration are classed as conversion markets (sell against FFS); 50% and above are switcher markets (sell against incumbents), matching the state-page framing.
Limitations: This is a MedicareInsights index, not CMS data, and is never citable as CMS data. Velocity for states without tracked counties inherits the tracked-set median, a rough proxy. Use for territory prioritization, not filings.

2027 disruption pipeline (plan years 2027-2028) curated

Source file: CMS newsroom, Federal Register, CMS rate and star publications (curated forward calendar)
Vintage: Through July 2026, covering plan years 2027-2028
Last updated: July 17, 2026
Cadence: Reviewed monthly; re-dated as CMS publishes each cycle milestone
Method: Analyst-curated calendar of dated CMS actions and statutory milestones that can disrupt members effective January 1, 2027 or during plan year 2027, each mapped to a sales response for AEP 2027 (October 15 to December 7, 2026) and a setup note for plan year 2028. Events marked final cite a published CMS action; expected marks a recurring statutory cycle not yet published for 2027; watch marks an open docket.
Limitations: Curated selection, not a complete feed. The AEP 2027 plays and 2028 setup notes are editorial strategy, not CMS guidance. Expected and watch items are forward-looking and may not occur as described.

Carrier vulnerability battlecards curated

Source file: Assembled from CMS Star Ratings, CMS non-renewal notices, CMS contract enrollment extracts, and a modeled benefit-value series
Vintage: Multiple vintages (shown per fact)
Last updated: July 17, 2026
Cadence: Updates as each underlying dataset refreshes
Method: Each card lists the facts a rep can cite when selling against a carrier: star trajectory (CMS Star Ratings), 2026 plan exits (CMS non-renewal notices), enrollment momentum (CMS contract enrollment extract), and benefit-value erosion (modeled, labeled as such). Every fact carries the vintage of the dataset it comes from; underlying provenance panels are on the page.
Limitations: The selection and phrasing of facts is editorial. The benefit-value series is a MedicareInsights model, labeled modeled, and is never citable as CMS data.

Flagship plan sample by carrier static extract

Source file: CMS MA landscape & CPSC files (selected contracts)
Vintage: Plan year 2026
Last updated: May 1, 2026
Cadence: Annual landscape; monthly enrollment
Method: Largest contracts per carrier with enrollment, stars, premium, MOOP.
Limitations: Sample of flagship plans, not the full ~5,700-plan universe.

County MA penetration — full coverage static extract

Source file: CMS Medicare Monthly Enrollment (county geography level)
Vintage: Pending first county ingest
Last updated: May 1, 2026
Cadence: Monthly, ~3 months in arrears (run: refresh_cms_data.py --counties)
Method: MA-and-other share of total Medicare beneficiaries per county from the CMS Monthly Enrollment county file; YoY velocity = penetration point change vs the same month one year earlier.
Limitations: Penetration and beneficiary base come from the Monthly Enrollment county file. Optional enrichment layers, added by refresh_cms_data.py only when their source files are supplied, attach to the same records: ACS 65+ population (pop65k; provenance acs_county_65plus), and CPSC-derived carrier count / top carrier / D-SNP share (provenance ma_county_markets) plus landscape $0-premium availability (provenance plan_landscape_zero_premium). Counties under ~20k beneficiaries are flagged low-reliability. Vintage is stamped by the ingest; until first run this dataset is empty and no page depends on it.

County population 65+ (Census ACS 5-year) static extract

Source file: U.S. Census Bureau, American Community Survey 5-year estimates (table B01001)
Vintage: Pending first ACS ingest
Last updated: May 1, 2026
Cadence: Annual (ACS 5-year release; run: refresh_cms_data.py --acs)
Method: Population aged 65 and over per county, summed from ACS table B01001 sex-by-age cells; used as a demographic denominator and runway context, not as the Medicare-eligible base.
Limitations: ACS is a survey with margins of error, largest for small counties. 65+ population is not identical to Medicare eligibility. Optional context layer; no core penetration figure depends on it.

County $0-premium MA-PD availability static extract

Source file: CMS Medicare Advantage / Part D Landscape source files
Vintage: Pending first landscape ingest
Last updated: May 1, 2026
Cadence: Annual (released each fall for the coming plan year; run: refresh_cms_data.py --landscape-file ...)
Method: A county is flagged $0-premium when at least one MA-PD plan in the CMS landscape file lists a $0 Part C monthly premium for that county.
Limitations: Reflects availability, not enrollment or the cheapest plan a given beneficiary qualifies for. Excludes SNP-only or employer plans not in the public landscape file. Optional layer; absent until the landscape file is ingested.

Update cadence

CMS publishes monthly enrollment roughly three months in arrears; star ratings each October; Part D benefit parameters each April; plan non-renewals each fall. The site rebuilds on each ingested release — the freshness badge on every page shows the exact data vintage and the date we last updated.

Penetration basis — read this before citing

State and county pages use the CMS monthly-file basis: MA + other health plan enrollment ÷ all Medicare beneficiaries (57.9% national, Feb 2026). The national trend page uses the pure-MA plan-year basis (50.8%, 2026). KFF's widely-cited eligible-only basis runs higher still. Every page states its basis; cite the basis with the number.

Get the 5 biggest shifts in Medicare data, monthly

One email per CMS release cycle: what changed in the new data, the five largest market shifts, and links to the updated answers. No product news, no filler.

No spam, unsubscribe anytime. See the privacy policy. Latest issue: Data release briefings →