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Medicare Advantage Enrollment Tracker · Idaho

Medicare Advantage Enrollment in Idaho

Idaho had 191,821 Medicare Advantage members in September 2026, by the CMS county file, which includes employer group plans. That is down 6.0% from Sep 2025, while the nation grew 2.0%. Idaho ranks 39th by members and holds 0.5% of the national total.

UnitedHealthcare leads with 42.7% of members who have a carrier label (contract file, September 2026). BCBS Idaho led a year earlier. Among individual plans, which leave out employer group coverage, enrollment is down 6.6% in the 12 months to September 2026.

By Senior Deal Club Standards Desk · Data as of September 2026 · Editorial policy

Data as ofCMS public files, monthly snapshot

  • These totals include employer and union group plans.
    Why this matters

    The CMS contract and county files count group plans that retirees get through a former employer. They are not plans you can pick on your own. Counts here are larger than the individual-plan counts on county pages.

  • Some months are missing from the source.
    Why this matters

    CMS did not publish every month. Lines break at a missing month instead of guessing a value. A dotted line, where shown, only joins the two sides.

Idaho at a glance

Medicare Advantage members

191,821

Idaho members by month: from 169K in Jan 2023 to 192K in Sep 2026

County file · Sep 2026. Includes employer group plans. Rank: 39.

County file · Sep 2026
CMS state, county and plan-type file (SCP). The same plans split by state and county, with employer and union group plans included. CMS hides counts of 10 or fewer.

12-month change

-6.0%

down 6.0 percent vs Sep 2025

County file · Sep 2026. National: +2.0%.

Share of national total

0.5%

County file · Sep 2026. Of jurisdictions that report every month.

Individual plan members

178,192

Individual MA · Sep 2026. Employer group plans left out.

Individual MA · Sep 2026
Individual Medicare Advantage plans (IND), from county data. Employer and union group plans are left out, so counts are smaller than in the other two files.

Largest carrier

UnitedHealthcare

42.7% of members with a carrier label. Contract file · Sep 2026.

Idaho members by month

Medicare Advantage members in Idaho

Members, by month.

County file · Sep 2026
CMS state, county and plan-type file (SCP). The same plans split by state and county, with employer and union group plans included. CMS hides counts of 10 or fewer.
Medicare Advantage members in IdahoLine chart, January 2023 to September 2026. Idaho: 192K in September 2026. Shaded bands mark months with no data.160K170K180K190K200K210K2023202420252026Idaho192K
Medicare Advantage members in IdahoLine chart, January 2023 to September 2026. Idaho: 192K in September 2026. Shaded bands mark months with no data.160K170K180K190K200K210K20232025Idaho192K
  • Idaho
  • Shaded: no data that month
View the data table
Medicare Advantage members in Idaho: values by month
MonthIdaho
Sep 2026192K
Aug 2026192K
Jul 2026191K
Jun 2026191K
May 2026190K
Apr 2026190K
Mar 2026189K
Feb 2026187K
Jan 2026177K
Dec 2025205K
Nov 2025205K
Oct 2025205K
Sep 2025204K
Aug 2025203K
Jul 2025202K
Jun 2025200K
May 2025203K
Apr 2025202K
Mar 2025201K
Feb 2025200K
Jan 2025196K
Dec 2024195K
Nov 2024194K
Oct 2024193K
Sep 2024193K
Aug 2024192K
Jul 2024191K
Jun 2024191K
May 2024190K
Apr 2024189K
Mar 2024188K
Feb 2024187K
Jan 2024186K
Dec 2023–
Nov 2023181K
Oct 2023180K
Sep 2023179K
Aug 2023178K
Jul 2023–
Jun 2023177K
May 2023176K
Apr 2023175K
Mar 2023175K
Feb 2023174K
Jan 2023169K

County file · Sep 2026. Employer group plans included.

Idaho and the nation, Jan 2023 = 100

Each line is members divided by members in the start month, times 100.

County file · Sep 2026
CMS state, county and plan-type file (SCP). The same plans split by state and county, with employer and union group plans included. CMS hides counts of 10 or fewer.
Idaho and the nation, Jan 2023 = 100Line chart, January 2023 to September 2026. Idaho: 113.2 in September 2026. National (same jurisdictions each month): 117.8 in September 2026. Shaded bands mark months with no data.1001101201302023202420252026National117.8Idaho113.2
Idaho and the nation, Jan 2023 = 100Line chart, January 2023 to September 2026. Idaho: 113.2 in September 2026. National (same jurisdictions each month): 117.8 in September 2026. Shaded bands mark months with no data.10011012013020232025National117.8Idaho113.2
  • Idaho
  • National (same jurisdictions each month)
  • Shaded: no data that month
View the data table
Idaho and the nation, Jan 2023 = 100: values by month
MonthIdahoNational (same jurisdictions each month)
Sep 2026113.2117.8
Aug 2026113117.8
Jul 2026112.8117.5
Jun 2026112.7117.4
May 2026112.4117.2
Apr 2026111.9116.9
Mar 2026111.5116.7
Feb 2026110.5116.3
Jan 2026104.2114.7
Dec 2025121115.9
Nov 2025121115.9
Oct 2025120.8115.7
Sep 2025120.4115.5
Aug 2025120.1115.3
Jul 2025119.5115
Jun 2025118114.8
May 2025119.5114.4
Apr 2025119.1114.2
Mar 2025118.8113.8
Feb 2025118113.4
Jan 2025115.7111.9
Dec 2024114.8112
Nov 2024114.6112
Oct 2024114.2111.7
Sep 2024113.9111.5
Aug 2024113.3111.2
Jul 2024113110.9
Jun 2024112.6110.7
May 2024112.1110.5
Apr 2024111.6110
Mar 2024111.2109.7
Feb 2024110.6109.3
Jan 2024110108.7
Dec 2023––
Nov 2023106.7105.9
Oct 2023106.2105.6
Sep 2023105.7105.2
Aug 2023105.3104.9
Jul 2023––
Jun 2023104.6104.1
May 2023104103.8
Apr 2023103.5103.4
Mar 2023103.1103
Feb 2023102.6102.2
Jan 2023100100

County file · Sep 2026. National line sums the jurisdictions that report in every month.

Individual plans

Individual plans leave out employer and union group coverage, so counts are smaller than in the county file.

Carrier share in Idaho

Share of members whose contract has a carrier label, September 2026 against September 2025.

Contract file · Sep 2026
CMS contract file (SCC). All Medicare Advantage contracts, with employer and union group plans included. It still lists Connecticut and Alaska.

UnitedHealthcare leads with 42.7% of members who have a carrier label (contract file, September 2026). BCBS Idaho led a year earlier.

UnitedHealthcare gained 3.9 points in 12 months; most of that change came in January 2026.

BCBS Idaho lost 20.7 points in 12 months; most of that change came in January 2026.

UnitedHealthcare and Humana together hold 50.9%, up 7.1 points from Sep 2025.

The market is less concentrated than a year earlier (direction only; the level depends on how carriers are grouped).

Carrier share, Sep 2025 to Sep 2026

Percent of members with a carrier label. Largest carriers.

Carrier share, Sep 2025 to Sep 2026Slope chart comparing Sep 2025 with Sep 2026. UnitedHealthcare: 38.7% to 42.7%; BCBS Idaho: 39.8% to 19.1%; Trinity Health Corporation: 2.0% to 12.1%; PacificSource: 5.0% to 9.0%; Humana: 5.1% to 8.2%; Molina: 7.1% to 6.9%.Sep 2025Sep 2026UnitedHealthcare 38.7%42.7% UnitedHealthcareBCBS Idaho 39.8%19.1% BCBS IdahoTrinity 2.0%12.1% TrinityPacificSource 5.0%9.0% PacificSourceHumana 5.1%8.2% HumanaMolina 7.1%6.9% Molina
Carrier share, Sep 2025 to Sep 2026Slope chart comparing Sep 2025 with Sep 2026. UnitedHealthcare: 38.7% to 42.7%; BCBS Idaho: 39.8% to 19.1%; Trinity Health Corporation: 2.0% to 12.1%; PacificSource: 5.0% to 9.0%; Humana: 5.1% to 8.2%; Molina: 7.1% to 6.9%.Sep 2025Sep 2026UHC 38.7%42.7%Blue Cross 39.8%19.1%Trinity 2.0%12.1%PacificSource 5.0%9.0%Humana 5.1%8.2%Molina 7.1%6.9%
View the data table
Carrier share, Sep 2025 to Sep 2026: Sep 2025 and Sep 2026
NameSep 2025Sep 2026Change
UnitedHealthcare38.7%42.7%+3.9 pts
BCBS Idaho39.8%19.1%−20.7 pts
Trinity Health Corporation2.0%12.1%+10.2 pts
PacificSource5.0%9.0%+4.0 pts
Humana5.1%8.2%+3.2 pts
Molina7.1%6.9%−0.2 pts

Contract file · Sep 2026. Employer group plans included.

Carrier share of Medicare Advantage members with a carrier label, Idaho, September 2026
CarrierShare, Sep 2026Share, Sep 2025ChangeMembers
UnitedHealthcare42.7%38.7%+3.9 pts80,596
BCBS Idaho19.1%39.8%−20.7 pts36,067
Trinity Health Corporation12.1%2.0%+10.2 pts22,897
PacificSource9.0%5.0%+4.0 pts17,083
Humana8.2%5.1%+3.2 pts15,536
Molina6.9%7.1%−0.2 pts12,945
Aetna/CVS1.2%1.1%+0.1 pts2,249
Elevance/Anthem0.5%0.4%0.0 pts885
Mitchell Family Office0.1%0.1%+0.1 pts250
All other carriers0.1%––193
Highmark/BCBS0.0%0.0%0.0 pts70
Intermountain Health Care–0.5%––

Insurer not assigned in CMS data: 0.9% of all members in Sep 2026, 3.9% in Sep 2025. Shares leave these members out. The unassigned share is above 3%, so treat share changes as rough. Contract IDs are renumbered each January, so this page follows carriers, not contracts. A contract that serves several states carries one carrier label, so a carrier can appear in a state where it is not a local plan. See the carrier view for the whole nation.

Biggest counties in Idaho

Individual plan members and the 12-month change for each county, from county data.

Individual MA · Sep 2026
Individual Medicare Advantage plans (IND), from county data. Employer and union group plans are left out, so counts are smaller than in the other two files.
Biggest counties in Idaho by individual Medicare Advantage members, September 2026
CountyMembers12-month changeLeading carrierLeader's share
Ada55,949−2.0%UnitedHealthcare38.9%
Canyon29,901+0.4%UnitedHealthcare35.3%
Kootenai18,080−6.8%UnitedHealthcare38.7%
Twin Falls10,614−2.1%PacificSource31.7%
Bonneville8,136−21.9%UnitedHealthcare63.0%
Bannock7,473−14.0%UnitedHealthcare52.1%
Bonner5,571−7.8%PacificSource43.1%
Bingham3,647−20.7%UnitedHealthcare56.8%
Payette3,556−1.2%BCBS Idaho24.7%
Gem3,412+0.2%BCBS Idaho29.8%

Browse all counties.

Common questions

How many people have Medicare Advantage in Idaho?

Idaho had 191,821 members in September 2026, by the CMS county file (employer group plans included). Individual plans, which leave out employer group coverage, had 178,192 members in September 2026.

Is Medicare Advantage growing in Idaho?

Enrollment is down 6.0% from Sep 2025 to Sep 2026, while the nation grew 2.0%. Among individual plans, which leave out employer group coverage, enrollment is down 6.6% in the 12 months to September 2026.

Which carrier has the most Medicare Advantage members in Idaho?

UnitedHealthcare leads with 42.7% of members who have a carrier label (contract file, September 2026). BCBS Idaho led a year earlier. UnitedHealthcare and Humana together hold 50.9%, up 7.1 points from Sep 2025. Shares leave out members whose contract has no carrier label: 0.9% of members.

Cite and download

Cite this page

Senior Deal Club Standards Desk. Medicare Advantage Enrollment in Idaho, data as of September 2026. Source: CMS public enrollment files. https://www.seniordealclub.com/medicare-advantage/enrollment/states/idaho

Download Idaho CSV

Data: CMS public enrollment files, in a monthly snapshot processed by TapQuality. Senior Deal Club is not affiliated with Medicare or any government agency.

These pages are educational. They are not plan advice. How the numbers are built · Editorial policy