Medicare in California serves about 6.6 million beneficiaries, with 47% enrolled in Medicare Advantage and the remainder on Original Medicare + Medigap. Average Medigap Plan G premium for a new 65-year-old enrollee: $158/mo. Stand-alone Part D plans average $47/mo.
Medicare Beneficiaries
6.6 million
Age 65+ and disabled
MA Enrollment
47%
% on Medicare Advantage
Avg Medigap Plan G
$158/mo
New enrollee, age 65
| Topic | Detail | Notes |
|---|---|---|
| Medicare Advantage plans available | 100+ | Varies by county; check medicare.gov plan finder |
| Top MA carriers | Kaiser Permanente, UnitedHealthcare, Anthem Blue Cross | Networks differ by county |
| Stand-alone Part D | $47/mo | Required if you have Original Medicare + Medigap |
| Annual guaranteed-issue Medigap switching | Yes — state protection applies | California Birthday Rule: Medigap holders may switch plans during a 60-day window starting on their birthday each year, with no medical underwriting. |
Medigap premiums vary by carrier, age, and ZIP code. The 2026 Part B premium is $202.90/month and Part B deductible is $283. Part D out-of-pocket cap is $2,100 in 2026.
California is the largest Medicare market in the country with over 6.6 million beneficiaries. Kaiser Permanente dominates the Medicare Advantage landscape in Northern and Southern California, running an integrated model where policyholders see Kaiser doctors at Kaiser facilities — a system that earns consistently high quality ratings but offers no out-of-network flexibility. Anthem Blue Cross and UnitedHealthcare compete for the PPO and non-Kaiser HMO market. In Los Angeles, the MA market is extraordinarily competitive with over 100 plan options. Cedars-Sinai Medical Center, UCLA Health, UCSF Health, and Dignity Health are major systems that participate across MA networks, though Kaiser's closed model means Kaiser MA enrollees stay exclusively within the Kaiser system.
California's Birthday Rule is one of the most consumer-friendly Medigap protections in the nation. Every year during a 60-day window starting on your birthday, you can switch to any Medigap plan with equal or lesser benefits from any insurer without answering health questions. This allows beneficiaries to shop for better premiums annually as they age, preventing the 'rate lock-in' that occurs in most other states. Medigap Plan G averages about $158/month in California, though premiums vary significantly from around $130 in inland areas to over $200 in the Bay Area. High-income Californians in San Francisco, Silicon Valley, and Marin County should anticipate IRMAA surcharges if income exceeds $103,000 individually.
In California, traditional Medicare combined with a Medigap supplement (typically Plan G or N) plus a stand-alone Part D plan provides nationwide access with predictable costs. Plan G covers everything except the $283 Part B deductible.
Medicare Advantage (Part C) plans bundle Medicare Parts A, B, and usually D into one private plan, often with $0 premium beyond Part B. Trade-offs include network restrictions and prior authorization. 47% of California beneficiaries currently choose MA.
California Birthday Rule: Medigap holders may switch plans during a 60-day window starting on their birthday each year, with no medical underwriting.
💡 California Pro Tip
California is one of the most plan-rich Medicare Advantage markets in the country. Los Angeles County beneficiaries typically have access to 100 or more plans. San Francisco and San Diego offer 60 to 80+ options. Even mid-sized markets like Sacramento and Fresno generally have 40 to 60 plans available.
Medigap Plan G premiums in California average approximately $158 per month for a 65-year-old, but there is substantial geographic variation. Premiums in the San Francisco Bay Area can exceed $200/month, while inland communities like Bakersfield or Riverside may see premiums closer to $130 to $140/month.
Yes — California's Birthday Rule gives every Medigap policyholder a 60-day window each year starting on their birthday to switch to a plan with equal or lesser benefits from any insurer, with no medical underwriting required. This is one of the strongest consumer protections for Medigap in the country and allows Californians to shop for lower premiums annually.
Beneficiary counts and MA enrollment percentages from CMS state-level Medicare data; premium averages from 2026 carrier rate filings for California. Verify current plan costs at medicare.gov before enrolling.
Jennifer Walsh
Editorial Lead, Health & Medicare
This article was researched and written by the Cover Forge USA editorial team against federal sources (NAIC, CMS, FEMA, DOL, SSA, state DOIs) and standard policy forms. Bylines organize content by topic — they do not assert individual licensure. See our editorial-policy for details.
Reviewed May 2026
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