{"main_topic":"health","sub_topic":"cms","topic":"medicare_enrollment","key":"health/cms/medicare_enrollment","version":"1.0.0","year_min":2013,"year_max":2026,"year_gaps":[],"update_frequency":"monthly","detail_levels":["counties","states"],"default_detail":"counties","path_template":"health/medicare_enrollment/year={year}/{detail}.parquet","grain":["year","county_fips","tract_geoid","month"],"title":"Medicare Enrollment and Medicare Advantage Share (CMS)","summary":"Medicare beneficiaries in Georgia and its counties by month, and the share in Medicare Advantage and other health plans.","description":"How many people on Medicare live in Georgia and each of its 159 counties, and how they get their Medicare: Original Medicare (fee-for-service) or Medicare Advantage and other private health plans. The headline is the Medicare Advantage share, the share of beneficiaries in Medicare Advantage and other health plans: statewide 26.4% in 2013, past half from 2022 (50.3%) and 55.4% in 2025. Monthly counts from January 2013 to July 2026 and CMS's annual figures (person-years, i.e. average monthly enrollment) for 2013-2025, from CMS's Medicare Monthly Enrollment data.","explorer":true,"search_aliases":{"en":["medicare part C","medicare enrollees","seniors on medicare","original medicare","medicare beneficiaries","private medicare plans","fee-for-service medicare","MA plans","medicare insurance","medicare health plans"],"es":["afiliados a medicare","personas mayores con medicare","medicare original","beneficiarios de medicare","planes privados de medicare","medicare advantage","parte C de medicare","seguro de medicare","planes de salud medicare","asegurados de medicare"]},"source":"Centers for Medicare & Medicaid Services (CMS), Medicare Monthly Enrollment, data.cms.gov dataset d7fabe1e-d19b-4333-9eff-e80e0643f2fd, July 2026 release","source_url":"https://data.cms.gov/summary-statistics-on-beneficiary-enrollment/medicare-and-medicaid-reports/medicare-monthly-enrollment","endpoint":"/api/v1/health/medicare_enrollment","columns":[{"name":"year","type":"integer","role":"year","nullable":false,"label":"Year","short_description":"","description":"Calendar year of Medicare enrollment, 2013-2026 (CMS's series starts January 2013). 2026 is partial (January-July in the July 2026 release): monthly rows only, no month = 'all' row.","valid_values":null,"example":2025,"unit":null,"value_min":null,"value_max":null,"null_meaning":null,"key_metric_grain_contributor":false,"metric_component":null},{"name":"county_fips","type":"string","role":"fk_county","nullable":true,"label":"County FIPS","short_description":"","description":"5-digit county FIPS code of the beneficiaries' residence (CMS BENE_FIPS_CD); NULL on the Georgia state row. CMS's Unknown county (13999) is left out.","valid_values":null,"example":"13121","unit":null,"value_min":null,"value_max":null,"null_meaning":null,"key_metric_grain_contributor":false,"metric_component":null},{"name":"tract_geoid","type":"string","role":"fk_tract","nullable":true,"label":"Tract GEOID","short_description":"","description":"Always NULL: CMS publishes state and county figures only. Kept for the health domain's standard key shape.","valid_values":null,"example":null,"unit":null,"value_min":null,"value_max":null,"null_meaning":null,"key_metric_grain_contributor":false,"metric_component":null},{"name":"month","type":"string","role":"categorical","nullable":false,"label":"Month","short_description":"'01'-'12' = enrolled in that month; 'all' = the year's person-year average.","description":"Calendar month, '01'-'12': beneficiaries enrolled in that month. 'all' is CMS's annual figure for the year, in person-years (months enrolled during the year / 12, i.e. average monthly enrollment): not December and not a sum of the months, which never add up (the same people are counted every month). 2026 has months '01'-'07' only and no 'all' row. Pin 'all' for annual figures.","valid_values":["all","01","02","03","04","05","06","07","08","09","10","11","12"],"example":"all","unit":null,"value_min":null,"value_max":null,"null_meaning":null,"key_metric_grain_contributor":true,"metric_component":null},{"name":"pct_medicare_advantage","type":"number","role":"metric","nullable":true,"label":"Share in Medicare Advantage and Other Health Plans","short_description":"Share of Medicare beneficiaries in Medicare Advantage and other health plans rather than Original Medicare.","description":"Share of the place's Medicare beneficiaries enrolled in Medicare Advantage and other health plans rather than Original Medicare: our calculation, num_beneficiaries_ma / num_beneficiaries, on the 0-1 scale (0.55 = 55%). On month = 'all' rows it is a share of person-years (average monthly enrollment). 'Other health plans' are other private plans CMS counts with Medicare Advantage, so this is not Medicare Advantage alone. For several counties, pool as SUM(num_beneficiaries_ma) / SUM(num_beneficiaries) within one year and month.","valid_values":null,"example":0.5536,"unit":"proportion","value_min":null,"value_max":null,"null_meaning":"NULL only where CMS suppresses the Medicare Advantage count or the total (none in the current release).","key_metric_grain_contributor":false,"metric_component":null},{"name":"num_beneficiaries","type":"integer","role":"metric","nullable":true,"label":"Medicare Beneficiaries","short_description":"","description":"All Medicare beneficiaries living in the place (CMS TOT_BENES): enrolled in the month, or person-years on the month = 'all' row. A count of people, so never sum it across months. The denominator of pct_medicare_advantage; equals num_beneficiaries_original_medicare + num_beneficiaries_ma (within 1 on annual rows).","valid_values":null,"example":2033942,"unit":"count","value_min":null,"value_max":null,"null_meaning":"Suppressed by CMS (1-10 beneficiaries, or counter-suppressed). Not seen on any state or county row in the current release.","key_metric_grain_contributor":false,"metric_component":"denominator"},{"name":"num_beneficiaries_original_medicare","type":"integer","role":"metric","nullable":true,"label":"Original Medicare Beneficiaries","short_description":"","description":"Beneficiaries in Original Medicare (fee-for-service; CMS ORGNL_MDCR_BENES): enrolled in the month, or person-years on the month = 'all' row. With num_beneficiaries_ma it splits num_beneficiaries (exactly on monthly rows, within 1 on annual rows). Never sum across months.","valid_values":null,"example":null,"unit":"count","value_min":null,"value_max":null,"null_meaning":"Suppressed by CMS (1-10 beneficiaries, or counter-suppressed so a suppressed count can't be recovered). No served row has one in the current release.","key_metric_grain_contributor":false,"metric_component":null},{"name":"num_beneficiaries_ma","type":"integer","role":"metric","nullable":true,"label":"Medicare Advantage and Other Health Plan Beneficiaries","short_description":"","description":"Beneficiaries in Medicare Advantage and other health plans (CMS MA_AND_OTH_BENES): enrolled in the month, or person-years on the month = 'all' row. The numerator of pct_medicare_advantage. Never sum across months.","valid_values":null,"example":null,"unit":"count","value_min":null,"value_max":null,"null_meaning":"Suppressed by CMS (1-10 beneficiaries, or counter-suppressed so a suppressed count can't be recovered). No served row has one in the current release.","key_metric_grain_contributor":false,"metric_component":"numerator"}],"key_metric":"pct_medicare_advantage","numeric_filter_columns":["pct_medicare_advantage","num_beneficiaries","num_beneficiaries_original_medicare","num_beneficiaries_ma"],"usage":"Star-schema fact table at state and county grain: state rows have county_fips NULL, county rows join the counties dimension on county_fips; tract_geoid is always NULL. Pin month = 'all' for annual figures (person-year averages) or one month '01'-'12'; never sum months (the same people are counted every month) and never sum the monthly rows to get 'all'. 2026 is only available by month (no 'all' row). For several counties, pool the key metric as SUM(num_beneficiaries_ma) / SUM(num_beneficiaries) within one year and month, never an average of county shares; for a trend use month = 'all' (or the same month each year). num_beneficiaries_original_medicare and num_beneficiaries_ma split num_beneficiaries, so never add the total to either. Read directly with DuckDB over Parquet.","limitations":"Georgia and its 159 counties (where beneficiaries live), monthly from January 2013 to July 2026. The annual row (month = 'all', 2013-2025) is CMS's person-year figure, average monthly enrollment: not everyone enrolled during the year, and not December's count. 2026 is partial (January-July): monthly rows only, no 'all' row. pct_medicare_advantage is our calculation, num_beneficiaries_ma / num_beneficiaries, from CMS's published counts. Person-years are the months each beneficiary was enrolled during the calendar year, summed and divided by 12, so the annual row is never a sum of months, and someone enrolled part of the year can count partly in more than one category; never treat 2026's latest month or an average of its months as the year's figure. 'Medicare Advantage and other health plans' is CMS's category: Medicare Advantage plus other private health plans that CMS's data dictionary does not list (in CMS enrollment reporting the term usually covers plans such as Medicare cost plans and PACE), so it is not Medicare Advantage alone and can differ from Medicare Advantage-only counts. Original Medicare plus Medicare Advantage equals the total exactly on monthly rows and within 1 on annual rows (CMS rounds each person-year count). The total counts everyone with Medicare Part A, Part B or both, aged and disabled. CMS publishes sex, race, age and entitlement counts only for all beneficiaries, never split by Original Medicare and Medicare Advantage, so they are not in this table. From the July 2026 release. CMS publishes a new release each month that restates the whole series from January 2013, so earlier months can be revised and the figures here are replaced when the data is refreshed. CMS suppresses counts of 1-10 beneficiaries and counter-suppresses others so a suppressed count can't be recovered (shown as '*'); those cells are NULL here and are never filled in from other figures. A 0 is a real count. No served row has a suppressed count in this release. CMS's Unknown county (13999) is left out: it is not a county and CMS suppresses all of it, so the county rows need not add up to Georgia's state row (state minus the sum of counties: 0 to 3 on monthly rows and -13 to -1 on annual rows, from that and from rounding each place's person-years on its own). A county's change from December to January can partly reflect CMS reassigning beneficiaries' county of residence, not a change in enrollment (inferred, since CMS does not document it: the state total moves smoothly while neighboring counties step in opposite directions; from December 2023 to January 2024, for example, Catoosa lost 739 beneficiaries while Walker gained 709). Counts are of people enrolled, not events: the same people are counted in every month, so months never add up. tract_geoid is always NULL.","null_semantics":{"suppressed_to_null":true,"zero_is_real":true},"available_years":[2013,2014,2015,2016,2017,2018,2019,2020,2021,2022,2023,2024,2025,2026],"schema_hash":"ae77c8f05bbab961343e3054bcc673fef45e82d5c6cfedbe925489e3b72e5831","tags":["health","centers for medicare & medicaid services","medicare_enrollment"],"granularity_description":"One row per year, county_fips, tract_geoid, month (geography columns are NULL at higher aggregation levels).","example_queries":[{"description":"Latest year (2026), counties detail","query":"SELECT * FROM medicare_enrollment WHERE year = 2026 LIMIT 100"},{"description":"Filter by month = all","query":"SELECT * FROM medicare_enrollment WHERE month = 'all' AND year = 2025 LIMIT 100"}],"foreign_keys":[{"column":"county_fips","target_object":"counties","target_columns":["county_fips"],"attribute_columns_added":["county_name"],"scope":"global"},{"column":"tract_geoid","target_object":"tracts","target_columns":["tract_geoid"],"attribute_columns_added":["tract_name"],"scope":"global"}],"filters":[{"param":"year","kind":"year_exact","type":"integer","multi_value":false,"enum_enforced":false,"values":null},{"param":"year_min","kind":"year_range","type":"integer","multi_value":false,"enum_enforced":false,"values":null},{"param":"year_max","kind":"year_range","type":"integer","multi_value":false,"enum_enforced":false,"values":null},{"param":"detail","kind":"detail","type":"string","multi_value":false,"enum_enforced":true,"values":["counties","states"],"default":"counties"},{"param":"county_fips","kind":"foreign_key","column":"county_fips","type":"string","multi_value":true,"enum_enforced":false,"values":null},{"param":"tract_geoid","kind":"foreign_key","column":"tract_geoid","type":"string","multi_value":true,"enum_enforced":false,"values":null},{"param":"month","kind":"categorical","column":"month","type":"string","multi_value":true,"enum_enforced":true,"values":["all","01","02","03","04","05","06","07","08","09","10","11","12"],"has_total":true,"total_value":"all","requires_single_value":false,"nullable":false,"null_filter_token":null}],"filter_hints":[],"non_additive":[{"column":"month","reason":"Enrollment is a count of people enrolled, not of events: the same beneficiaries are counted again in every month, so months never add up to a year. The 'all' row is CMS's person-year figure (average monthly enrollment), not the sum of the months."},{"column":"num_beneficiaries","reason":"The total is Original Medicare plus Medicare Advantage and other health plans: adding it to either counts those beneficiaries twice.","with":["num_beneficiaries_original_medicare","num_beneficiaries_ma"]}],"partitions":[],"value_implications":[],"year_meaning":null,"pooled_rates":[],"series_breaks":[],"year_window":null,"pooled_min_count":null,"values_endpoint":"/api/v1/health/medicare_enrollment/values"}