If you live in California and have a Medicare Supplement, also called Medigap, you have a yearly right that is stronger than the one in any other state we work in. Every year, starting on your birthday, you get at least 60 days to switch to another Medigap policy without health questions.
That rule shapes the rest of this guide. Medicare Open Enrollment is open now, October 15 through December 7, 2026, but it covers Medicare Advantage and drug plans, not Medigap. So we start with the supplement side, then walk through the Advantage and Part D market for 2027.
One thing to know up front. California has the largest Medicare market in the country, and this guide names all of it, not just the part any one agency can sell you.
California's birthday rule gives Medigap holders a yearly window
If you already have a Medigap policy, you get at least 60 days each year, starting on your birthday, to switch without health questions.
California Insurance Code section 10192.11(h)(1) gives you "an annual open enrollment period lasting 60 days or more, commencing with the individual's birthday." During that time you may buy any Medicare supplement policy "that offers benefits equal to or lesser than those provided by the previous coverage."
In that window the company cannot deny you or put conditions on your coverage. It also cannot charge you more because of your health, your past claims, the care you have had, or a medical condition. The catch: you must already be covered by another Medigap policy when the window opens.
How California's Medigap birthday rule works
| Question | Answer |
|---|---|
| When does it open? | On your birthday. It does not open before. |
| How long does it last? | 60 days or more. |
| Who can use it? | People who already have a Medigap policy. |
| What can you buy? | Any Medigap policy with equal or lesser benefits. |
| What can the company not do? | Deny you, add conditions, or charge you more because of your health. |
Scroll the table sideways to see every column.
Source: California Insurance Code section 10192.11(h)(1).
Compare that with the other states we work in. Oregon's birthday window runs 30 days from your birthday. Arizona, Alabama and Texas have no birthday rule. California's is the most generous of the five.
Plan G has the same benefits at every company, so price is what you shop
Medigap benefits are set by plan letter. A Plan G from one company covers the same things as a Plan G from another.
Medigap plans are standardized. Medicare's own guide puts it plainly: all plans with the same letter offer the same basic benefits, no matter which company you buy from. So when you compare two Plan G policies, the benefits do not differ. What differs is the premium today, and how often that company has raised it.
That is why the birthday rule matters so much here. It gives you a chance every year to move to a lower price for the same coverage, without health questions.
The California Department of Insurance lists 20 companies that sell Medigap in the state. 19 of them list Plan G as an individual policy for people 65 and over. The 20th, AARP/United Healthcare Insurance Company, lists no individual policies. It sells through an AARP group policy, so you must be an AARP member to buy it.
- ACE Property & Casualty Insurance Company
- AARP/United Healthcare Insurance Company
- American Retirement Life Insurance Company
- Blue Cross of CA (dba Anthem Blue Cross)
- California Physicians (dba Blue Shield of CA)
- Continental Life Insurance Company of Brentwood, Tennessee
- Everence Association, Inc.
- First Health Life & Health Insurance Company
- Humana Insurance Company
- Insurance Company of North America
- ManhattanLife Insurance & Annuity Company
- Medico Insurance Company
- Physicians Select Insurance Company
- State Farm Mutual Automobile Insurance Company
- Tier One Insurance Company
- Transamerica Life Insurance Company
- United American Insurance Company
- United World Life Insurance Company
- USAA Life Insurance Company
- Washington National Insurance Company
Who can use the birthday rule, and who cannot
It is a switching right for people who already have Medigap. It is not a way back in from Medicare Advantage.
Four limits matter.
- You must already have a Medigap policy. If you are in a Medicare Advantage plan, the birthday rule does not cover a move to Medigap.
- You can keep the same benefits or take fewer. You can move from one company's Plan G to another company's Plan G, or to a plan that covers less. You cannot use the window to move up to more coverage.
- The window starts on your birthday. An application sent before your birthday falls outside it. Plan your switch for the days after.
- Your first window is separate. Federal law gives you a one-time six-month Medigap open enrollment period. It starts when you are 65 and enrolled in Part B.
October 15 to December 7 is for Medicare Advantage and drug plans
Open Enrollment does not open a Medigap window. In California, your birthday does.
Mixing these up can be costly.
What you can do between October 15 and December 7: join, switch, or drop a Medicare Advantage plan, and join, switch, or drop a Part D drug plan. Changes take effect January 1, 2027.
What this window does not do: it does not give you a right to buy a Medicare Supplement. You can apply for one any time of year. But the protection from health questions comes from your own windows, not from this one.
California's Medicare Advantage market for 2027: 394 plans, 55 counties
38 organizations sell Medicare Advantage in California. Your county has only some of their plans.
CMS counts 394 Medicare Advantage plans in California for 2027, down from 402 in 2026. 135 of them are Special Needs Plans, which are open only to people who meet eligibility rules. The other 259 are open to anyone with Medicare who lives in the plan's area.
The average monthly Medicare Advantage premium in California went up, from $13.77 in 2026 to $14.12 in 2027, according to CMS.
California Medicare Advantage organizations with the most plans, 2027
| Organization | Plans |
|---|---|
| SCAN Health Plan | 64 |
| Kaiser Permanente | 48 |
| Alignment Health Plan | 46 |
| UnitedHealthcare | 42 |
| Humana | 30 |
| Aetna Medicare | 26 |
| Anthem Blue Cross | 22 |
| Blue Shield of California | 20 |
| Wellcare | 14 |
| Anthem Blue Cross Partnership Plan | 14 |
Scroll the table sideways to see every column.
Counted from the CMS CY2027 Landscape file by marketing name. Counts include Special Needs Plans. A plan count says nothing about cost or quality, and no organization sells all of its plans in every county.
Those ten account for 326 of the 394 plans. 28 other names sell the rest. Some are local plans in one county for people with both Medicare and Medi-Cal, such as L.A. Care Health Plan, San Francisco Health Plan and Santa Clara Family Health Plan. Counted by parent company, there are 35 organizations in all.
No company sells everywhere. Each one picks its counties, so the list in Los Angeles looks nothing like the list in Humboldt. That is why the statewide number is the wrong place to start. Medicare.gov’s Plan Finder shows every plan sold where you live.
Your county decides what you can buy
Los Angeles County has 124 Medicare Advantage plans. Lassen County has 2.
Plans are sold county by county, so the statewide count of 394 does not tell you what you can buy. Here is how wide the spread is.
Medicare Advantage plans by California county, 2027
| County | All plans | Open to anyone |
|---|---|---|
| Los Angeles | 124 | 70 |
| Orange | 111 | 62 |
| San Bernardino | 95 | 49 |
| Riverside | 88 | 47 |
| San Diego | 85 | 46 |
| San Francisco | 46 | 25 |
| Fresno | 42 | 19 |
| Sacramento | 32 | 16 |
| Nevada | 5 | 3 |
| Lassen | 2 | 2 |
Scroll the table sideways to see every column.
Counted from the CMS CY2027 Landscape file. The difference between the two columns is Special Needs Plans, which have eligibility requirements.
In Los Angeles, the work is narrowing 70 open plans to the few that cover your doctors and your drugs. In Nevada County or Lassen County, the choice is small. There, Original Medicare with a Medigap policy can be the option worth a close look, and the birthday rule keeps that choice open year after year.
Drug plans: 10 standalone plans, and a lower premium for every current enrollee
CMS says 100% of Californians in a standalone drug plan can find a lower premium than they paid in 2026.
California has 10 standalone Part D drug plans for 2027, from five organizations. Humana has 3. Blue Shield of California, Wellcare and UnitedHealthcare have 2 each. Blue Cross and Blue Shield of IL, NM, OK, TX has 1.
According to CMS, 100% of people in a standalone drug plan in California can get one with a lower premium than they paid in 2026. And 32.27% of them get Extra Help. But the premium is only part of what you pay. Two program-wide numbers moved for 2027.
Medicare's standard Part D benefit, set by CMS
| What it is | 2026 | 2027 |
|---|---|---|
| Highest deductible Medicare allows | $615 | $700 |
| Out-of-pocket cap, after which you pay $0 for covered drugs | $2,100 | $2,400 |
Scroll the table sideways to see every column.
Set by CMS for the defined standard benefit. Many plans charge a lower deductible or none at all, and the cap includes whatever deductible you pay. Your Annual Notice of Change lists your own plan's figures.
The cap is the one to watch if you take costly drugs. Once your out-of-pocket drug spending reaches it, you pay nothing more for covered drugs that year. Moving it to $2,400 means someone who reaches the cap pays up to $300 more in 2027.
So check how your own drugs are covered before you look at premiums: the tier, any limits, and the price at your pharmacy.
What to do before December 7, and before your birthday
Five things, and the first one is already in your mailbox.
Doing nothing is a fine choice for plenty of people. Just check first.
- Read your Annual Notice of Change. If you have a Medicare Advantage or drug plan, your plan had to get it to you by September 30. It lists what changes for 2027.
- If you have Medigap, mark your birthday. Your window opens that day and lasts at least 60 days. Watch for your company's notice before it opens.
- Compare Plan G prices from more than one company. The benefits match, so the premium and the company's rate history are what you are comparing.
- Check your drugs and your doctors. Drug lists and Medicare Advantage networks change every year.
- Compare total cost, not just premium. Premium plus deductible plus what your prescriptions cost on that plan.