{
"generated": "2026-08-28",
"generator": "tools/build_audit_fixes_2026_08_28.py",
"note": "Single source of truth for dataset vintage and status. Every dataset panel on /methodology/ has an entry here; page copy must derive from this, never the other way round.",
"canonical": {
"county_enrollment": "ma_county_enrollment",
"national": "cms_geo_canonical.json#national",
"state": "cms_geo_canonical.json#states"
},
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"ma_other_health_plan_enrollment_and_share_county_state_and_n": {
"name": "MA & other health plan enrollment and share — county, state and national live",
"status": "LIVE",
"provenance_class": "live",
"source": "Medicare Monthly Enrollment (CCW-derived national, state and county beneficiary counts; data.cms.gov dataset d7fabe1e-d19b-4333-9eff-e80e0643f2fd, public API)",
"source_url": "https://data.cms.gov/summary-statistics-on-beneficiary-enrollment/medicare-and-medicaid-reports/medicare-monthly-enrollment",
"vintage": "April 2026",
"last_updated": "July 31, 2026",
"cadence": "Monthly. This product is CCW-derived and posts roughly three months after the reporting month; the April 2026 file is the newest published. Cadence differs by product — see the four enrollment sources named below.",
"method": "Current. Each geography reads its own CMS record from the Medicare Monthly Enrollment dataset (BENE_GEO_LVL = National, State or County) as MA_AND_OTH_BENES / TOT_BENES. Summing the county rows is run as a reconciliation calculation and reported as a residual, not used as the published value. The national residual is 689,033 beneficiaries (0.98%), almost all of it the CMS Foreign row plus a suppressed unknown-geography row; state residuals have a median of 0.065 points and a maximum of 0.30 points. See current production methodology.",
"limitations": "Health plan share here is measured against all Medicare beneficiaries (Parts A and/or B), not the KFF eligible-only basis, which runs ~4pts higher.",
"panel": "MA & other health plan enrollment and share — county, state and national live",
"grain": "national, state and county",
"join_keys": [
"fips",
"state_abbr"
],
"files": [
"ma_county_penetration_2026-04.csv",
"ma_counties.json",
"cms_geo_canonical.json"
],
"blocks": [
"/market/",
"/market/counties/",
"/market/ma-penetration-by-state/",
"/market/states/*",
"opportunity score",
"market brief"
],
"vintage_html": "April 2026",
"last_updated_html": "July 31, 2026"
},
"national_ma_vs_original_medicare_2010_2026_static_extract": {
"name": "National MA vs Original Medicare, 2010–2026 static extract",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "CMS Medicare Monthly Enrollment; CMS MA landscape files (historical)",
"source_url": "https://data.cms.gov/summary-statistics-on-beneficiary-enrollment/medicare-and-medicaid-reports/medicare-monthly-enrollment",
"vintage": "April 2026",
"last_updated": "July 31, 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.",
"panel": "National MA vs Original Medicare, 2010–2026 static extract",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "April 2026",
"last_updated_html": "July 31, 2026"
},
"county_level_ma_market_snapshot_the_counties_then_tracked_da": {
"name": "County-level MA market snapshot (the counties then tracked (dataset withdrawn)) static extract",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "Monthly MA Enrollment by State/County/Contract (CPSC family), from CMS Medicare Advantage/Part D Contract and Enrollment Data",
"source_url": "https://data.cms.gov/summary-statistics-on-beneficiary-enrollment/medicare-and-medicaid-reports/medicare-monthly-enrollment",
"vintage": "WITHDRAWN — historical only, not used in current production analytics. See the archive.",
"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 the counties then tracked (a dataset since withdrawn — see below).",
"limitations": "Covers the counties then tracked (dataset withdrawn), not all ~3,100. Velocity = simple YoY penetration point change.",
"panel": "County-level MA market snapshot (the counties then tracked (dataset withdrawn)) static extract",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "WITHDRAWN — historical only, not used in current production analytics. See the archive.",
"last_updated_html": "May 1, 2026"
},
"carrier_footprint_by_state_static_extract": {
"name": "Carrier footprint by state static extract",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "Monthly Enrollment by Contract/Plan/State/County (CPSC), March 2026 reporting month, from CMS Medicare Advantage/Part D Contract and Enrollment Data; CMS landscape files. Verified August 26, 2026 against the CMS monthly report file list. The earlier “(OEC)” label was withdrawn: the Monthly Online Enrollment Center (OEC) Report is a different CMS report and is not used here.",
"source_url": "https://www.cms.gov/medicare/health-drug-plans/medicare-advantage-rates-statistics",
"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.",
"panel": "Carrier footprint by state static extract",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "March 2026",
"last_updated_html": "May 1, 2026"
},
"part_d_benefit_parameters_cy2022_cy2026_static_extract": {
"name": "Part D benefit parameters, CY2022–CY2026 static extract",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "CMS Part D benefit parameter announcements; IRA statutory provisions",
"source_url": "https://www.cms.gov/medicare/health-drug-plans/part-d",
"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.",
"panel": "Part D benefit parameters, CY2022–CY2026 static extract",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "CY2026 final parameters",
"last_updated_html": "April 7, 2026"
},
"dual_eligible_density_by_state_static_extract": {
"name": "Dual-eligible density by state static extract",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "CMS Medicare-Medicaid dual enrollment data (MMCO quarterly)",
"source_url": "https://www.cms.gov/medicare-medicaid-coordination",
"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.",
"panel": "Dual-eligible density by state static extract",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "2025 Q4",
"last_updated_html": "March 15, 2026"
},
"2026_plan_exits_and_member_migration_curated": {
"name": "2026 plan exits and member migration curated",
"status": "CURATED",
"provenance_class": "curated",
"source": "CMS 2026 non-renewal notices; carrier investor disclosures",
"source_url": "https://www.cms.gov/medicare/health-drug-plans/medicare-advantage-rates-statistics",
"vintage": "Plan year 2026 (announced fall 2025)",
"last_updated": "January 20, 2026",
"cadence": "Annual (non-renewals announced each fall)",
"method": "Field-level provenance, because these five figures do not share a source. Terminated plan count (148) and affected enrollment (2.1M): compiled from 2026 non-renewal announcements and carrier investor disclosures; not reproducible from a CMS file ingested by this site. Migration destinations: January 2026 enrollment reconciliation, directional. Active-shopping share (62%): an estimate derived from that reconciliation, not a CMS-published measure. Carrier attribution: carrier disclosures. The dataset is classified curated until a service-area and plan-year crosswalk ingest can regenerate the headline totals from a named file.",
"limitations": "Migration percentages are early-year estimates; 'active shopping' share is directional.",
"panel": "2026 plan exits and member migration curated",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "Plan year 2026 (announced fall 2025)",
"last_updated_html": "January 20, 2026"
},
"net_benefit_value_pmpm_vs_2022_baseline_modeled": {
"name": "Net benefit value (PMPM) vs 2022 baseline modeled",
"status": "MODELED",
"provenance_class": "modeled",
"source": "Modeled from CMS bid/landscape data — MedicareInsights estimate",
"source_url": "https://www.cms.gov/medicare/health-drug-plans/medicare-advantage-rates-statistics",
"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.",
"panel": "Net benefit value (PMPM) vs 2022 baseline modeled",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "Plan years 2022–2026",
"last_updated_html": "April 15, 2026"
},
"star_rating_trajectory_by_carrier_static_extract_derived": {
"name": "Star rating trajectory by carrier static extract derived",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "CMS MA Star Ratings (annual, published each October); CMS prior-auth reporting",
"source_url": "https://www.cms.gov/medicare/health-drug-plans/part-c-d-performance-data",
"vintage": "2026 Star Ratings (published Oct 2025)",
"last_updated": "February 10, 2026",
"cadence": "Annual (October)",
"method": "MedicareInsights enrollment-weighted derived carrier 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.",
"panel": "Star rating trajectory by carrier static extract derived",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "2026 Star Ratings (published Oct 2025)",
"last_updated_html": "February 10, 2026"
},
"star_measure_level_erosion_top_carriers_static_extract": {
"name": "Star measure-level erosion, top carriers static extract",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "CMS Star Ratings measure-level data (Part C & D performance files)",
"source_url": "https://www.cms.gov/medicare/health-drug-plans/part-c-d-performance-data",
"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.",
"panel": "Star measure-level erosion, top carriers static extract",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "2022–2026 rating years",
"last_updated_html": "February 10, 2026"
},
"cms_policy_developments_curated": {
"name": "CMS policy developments curated",
"status": "CURATED",
"provenance_class": "curated",
"source": "CMS.gov newsroom, Federal Register, CMS fact sheets (curated)",
"source_url": "https://www.cms.gov/newsroom",
"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.",
"panel": "CMS policy developments curated",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "Through July 2026",
"last_updated_html": "July 1, 2026"
},
"regulatory_reference_library_curated": {
"name": "Regulatory reference library curated",
"status": "CURATED",
"provenance_class": "curated",
"source": "CMS Medicare Managed Care Manual (Pub. 100-16); IRA 2022; 2027 Advance Notice",
"source_url": "https://www.cms.gov/regulations-and-guidance/guidance/manuals",
"vintage": "Current through the CY2027 Advance Notice (published January 26, 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.",
"panel": "Regulatory reference library curated",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "Current through the CY2027 Advance Notice (published January 26, 2026)",
"last_updated_html": "February 15, 2026"
},
"snp_enrollment_by_plan_and_state_live": {
"name": "SNP enrollment by plan and state live",
"status": "LIVE",
"provenance_class": "live",
"source": "CMS Special Needs Plan Comprehensive Report — plan-level tab SNP_REPORT_PART_17",
"source_url": "https://www.cms.gov/data-research/statistics-trends-and-reports/medicare-advantagepart-d-contract-and-enrollment-data/special-needs-plan-snp-data",
"vintage": "August 2026",
"last_updated": "August 24, 2026",
"cadence": "Monthly, and it posts close to its reporting month — so this file runs ahead of the CCW-derived Medicare Monthly Enrollment product, which lags about three months. That difference is why the D-SNP capture figure is a cross-vintage proxy. Published only as a zip archive, not through the CMS data API, so the ingest is manual.",
"method": "1,803 plan records carrying contract, plan, type (D/C/I-SNP), integration status, qualifying conditions and enrollment. National totals by type and by integration status are taken from the report's own summary tabs rather than re-derived; plan rows sum to the CMS published total of 8,437,333 exactly. Parent-brand grouping is inferred by keyword from the contract name and is labeled as such on the page.",
"limitations": "State is the finest geography CMS publishes, and only for single-state plans; 44 multi-state plans (146,934 enrollees, 1.7%) are excluded from state rollups rather than split arbitrarily. Plans under 11 enrollees are suppressed into three Under-11 aggregate rows with no state. The D-SNP capture proxy compares August 2026 enrollment to the April 2026 dual population and is suppressed for Puerto Rico.",
"panel": "SNP enrollment by plan and state live",
"grain": "contract, plan and state",
"join_keys": [
"state_abbr",
"contract_id",
"plan_id"
],
"files": [
"snp_2026-08.json",
"snp_by_state_2026-08.csv",
"snp_plans_2026-08.csv"
],
"blocks": [
"/market/snp/",
"/marketing/dsnp/",
"D-SNP capture proxy"
],
"vintage_html": "August 2026",
"last_updated_html": "August 24, 2026"
},
"growth_runway_index_by_state_and_county_modeled": {
"name": "Growth runway index by state and county modeled",
"status": "MODELED",
"provenance_class": "modeled",
"source": "MedicareInsights index computed from CMS Medicare Monthly Enrollment and CPSC county extracts",
"source_url": "https://data.cms.gov/summary-statistics-on-beneficiary-enrollment/medicare-and-medicaid-reports/medicare-monthly-enrollment",
"vintage": "WITHDRAWN — historical only, not used in current production analytics. Superseded by the April 2026 canonical records",
"last_updated": "July 31, 2026",
"cadence": "No longer refreshed — withdrawn August 24, 2026",
"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 used at the time. That framing is no longer used on any current page.",
"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.",
"panel": "Growth runway index by state and county modeled",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "WITHDRAWN — historical only, not used in current production analytics. Superseded by the April 2026 canonical records",
"last_updated_html": "July 31, 2026"
},
"2027_disruption_pipeline_plan_years_2027_2028_curated": {
"name": "2027 disruption pipeline (plan years 2027-2028) curated",
"status": "CURATED",
"provenance_class": "curated",
"source": "CMS newsroom, Federal Register, CMS rate and star publications (curated forward calendar)",
"source_url": "https://www.cms.gov/newsroom",
"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.",
"panel": "2027 disruption pipeline (plan years 2027-2028) curated",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "Through July 2026, covering plan years 2027-2028",
"last_updated_html": "July 17, 2026"
},
"carrier_vulnerability_battlecards_curated": {
"name": "Carrier vulnerability battlecards curated",
"status": "CURATED",
"provenance_class": "curated",
"source": "Assembled from CMS Star Ratings, CMS non-renewal notices, CMS contract enrollment extracts, and a modeled benefit-value series",
"source_url": "https://www.cms.gov/medicare/health-drug-plans/part-c-d-performance-data",
"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.",
"panel": "Carrier vulnerability battlecards curated",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "Multiple vintages (shown per fact)",
"last_updated_html": "July 17, 2026"
},
"flagship_plan_sample_by_carrier_static_extract": {
"name": "Flagship plan sample by carrier static extract",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "CMS MA landscape & CPSC files (selected contracts)",
"source_url": "https://www.cms.gov/medicare/health-drug-plans/medicare-advantage-rates-statistics",
"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.",
"panel": "Flagship plan sample by carrier static extract",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "Plan year 2026",
"last_updated_html": "May 1, 2026"
},
"county_ma_other_health_plan_share_full_coverage_static_extra": {
"name": "County MA & other health plan share — full coverage static extract",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "CMS Medicare Monthly Enrollment (county geography level)",
"source_url": "https://data.cms.gov/summary-statistics-on-beneficiary-enrollment/medicare-and-medicaid-reports/medicare-monthly-enrollment",
"vintage": "April 2026",
"last_updated": "July 31, 2026",
"cadence": "Monthly, CCW-derived, roughly three months after the reporting month (run: refresh_cms_data.py --counties). Not the same rhythm as the CPSC contract files or the SNP Comprehensive Report, which post close to their reporting month.",
"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.",
"panel": "County MA & other health plan share — full coverage static extract",
"grain": "county",
"join_keys": [
"fips"
],
"files": [
"ma_county_penetration_2026-04.csv"
],
"blocks": [
"/market/counties/",
"county explorer CSV"
],
"vintage_html": "April 2026",
"last_updated_html": "July 31, 2026"
},
"county_population_65_census_acs_5_year_static_extract": {
"name": "County population 65+ (Census ACS 5-year) static extract",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "U.S. Census Bureau, American Community Survey 5-year estimates (table B01001)",
"source_url": "https://www.census.gov/programs-surveys/acs",
"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 market-headroom 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.",
"panel": "County population 65+ (Census ACS 5-year) static extract",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "Pending first ACS ingest",
"last_updated_html": "May 1, 2026"
},
"county_0_premium_ma_pd_availability_static_extract": {
"name": "County $0-premium MA-PD availability static extract",
"status": "STATIC_EXTRACT",
"provenance_class": "static-extract",
"source": "CMS Medicare Advantage / Part D Landscape source files",
"source_url": "https://www.cms.gov/medicare/health-drug-plans/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.",
"panel": "County $0-premium MA-PD availability static extract",
"grain": null,
"join_keys": null,
"files": null,
"blocks": null,
"vintage_html": "Pending first landscape ingest",
"last_updated_html": "May 1, 2026"
},
"ma_county_enrollment": {
"name": "MA and other health plan share by geography (Medicare Monthly Enrollment)",
"status": "LIVE",
"source": "CMS Medicare Monthly Enrollment (BENE_GEO_LVL=County)",
"source_url": "https://data.cms.gov/summary-statistics-on-beneficiary-enrollment/medicare-enrollment/medicare-monthly-enrollment",
"cms_dataset_id": "d7fabe1e-d19b-4333-9eff-e80e0643f2fd",
"vintage": "April 2026",
"vintage_iso": "2026-04",
"prior_vintage": "April 2025",
"ingested": "2026-07-31",
"cadence": "Monthly, published roughly three months in arrears. This cadence applies ONLY to the CCW-derived Medicare Monthly Enrollment product; the MA/Part D contract and enrollment reports (CPSC, SNP Comprehensive Report) publish much closer to the reporting month.",
"methodology_version": "2026-08-24",
"geography": "US counties, BENE_GEO_LVL=County",
"coverage": {
"counties": 3199,
"jurisdictions": 53
},
"numerator": "MA_AND_OTH_BENES — beneficiaries in a Medicare Advantage or other health plan (includes cost plans, PACE and demonstrations)",
"denominator": "TOT_BENES — all Medicare beneficiaries in the county with Part A and/or Part B",
"formula": "penetration_pct = MA_AND_OTH_BENES / TOT_BENES * 100, rounded to 1 decimal",
"derived": true,
"aggregates": {
"national_total_beneficiaries": 70408037,
"national_ma_and_other": 36012033,
"national_share_pct": 51.1,
"county_sum_total_beneficiaries": 69719004,
"county_sum_ma_and_other": 36006944,
"county_sum_share_pct": 51.6,
"geography_residual_beneficiaries": 689033,
"geography_residual_note": "CMS Foreign row (567,123 beneficiaries, 7,392 in a health plan) plus the suppressed Unknown row. No county assignment, so county aggregation excludes them."
},
"download": "/assets/data/ma_county_penetration_2026-04.csv",
"limitations": [
"The numerator MA_AND_OTH_BENES counts Medicare Advantage plus cost plans, PACE and demonstrations. It is not an MA-only figure and must not be labelled \"Medicare Advantage\" without qualification.",
"The denominator TOT_BENES includes beneficiaries with Part A only, who cannot enrol in Medicare Advantage. Sources using an eligible-only denominator report a higher share; that is a basis difference, not an error.",
"CMS suppresses small cells; counties without both counts are absent rather than estimated.",
"Summing county rows excludes 689,033 beneficiaries CMS reports without a county, which raises a county-derived national share by about half a point. Direct CMS records are used for national and state figures.",
"This file carries no carrier, plan or star-rating detail. Any such figure needs the CPSC ingest, which is not yet built."
],
"open_issues": [
"RESOLVED 2026-08-26: national and state figures now come from the direct CMS records for those geographies. The county aggregation is published alongside them with its residual. See docs/data-qa-2026-08-25.md."
],
"dataset_product": "Medicare Monthly Enrollment (CCW-derived; national, state and county beneficiary measures)",
"canonical_rule": "The direct CMS record is canonical for its own geography. National uses the CMS National record, state uses the CMS State record, county uses county records. County aggregation is published as a reconciliation calculation with its residual, never as a replacement.",
"grain": "national, state and county",
"join_keys": [
"fips",
"state_abbr"
],
"files": [
"ma_county_penetration_2026-04.csv"
],
"blocks": [
"every market surface"
]
}
},
"withdrawn": {
"ma_county_markets": {
"name": "76-county market extract",
"status": "WITHDRAWN",
"withdrawn_on": "2026-08-24",
"reason": "Not reproducible from any CMS file. Audited 2026-08-24 against the April 2026 county file: denominators differed by 1.4x to 995x, penetration differed by a mean of 8.5 and up to 35.5 percentage points across 76 counties, the 2023-2026 history was smooth and monotonic in a way observed data is not, and at least one FIPS was wrong (48173 Glasscock was labelled Galveston, which is 48167). It was displayed as a CMS 'static extract', which it was not.",
"replaced_by": "ma_county_enrollment",
"archived_at": "/assets/data/archive/ma_county_markets_plan-year-2026-with-2023-2026-penetration-history.csv"
},
"ma_state_enrollment_feb_2026": {
"name": "State enrollment, February 2026",
"status": "SUPERSEDED",
"reason": "A February 2026 vintage that does not reconcile with the April 2026 CMS records. State and national figures now come from the direct CMS state and national records for those geographies; the county aggregation is published beside them as a reconciliation, never as a replacement.",
"replaced_by": "ma_county_enrollment",
"removed_from_live_path": "2026-08-28"
}
},
"authority": "This file is the source for each dataset's provenance class, vintage and last-updated date. tools/build_registry_authority.py writes those three fields into the /methodology/ panels; edits made to the page are overwritten. Source file, cadence, method and limitations stay hand-authored in the page because they carry links and markup."
}