California gives Medicare Supplement (Medigap) policyholders something most states don't: a 60-day window each year, starting on your birthday, to switch policies with no medical underwriting. California's "birthday rule" lets you move to a Medigap policy of equal or lesser benefits from any insurer, regardless of your health. This guide explains how the birthday rule works, how to use it, how the standardized A-through-N plans fit together, which plans are closed to newer enrollees, and who regulates Medigap in California.
How Medigap works in California
A Medigap policy is private insurance that pays the deductibles and coinsurance Original Medicare leaves to you. Medigap (Medicare Supplement Insurance) works only alongside Original Medicare, not with a Medicare Advantage plan, and each policy covers one person. A married couple who both want coverage need two policies.
California uses the federal standardized framework. Medigap is sold as lettered plans, A through N, and the benefits inside each letter are fixed by federal rule. A Plan G from one California insurer covers exactly what a Plan G from another covers, per the Medicare.gov plan-benefit comparison. Insurers compete on price, service, and rate stability, not on what the plan pays. That makes the plan letter your first decision and the insurer your second.
The gaps Medigap closes are real. After the Part B deductible ($283 in 2026), Original Medicare pays 80% of the approved amount for most outpatient care and leaves you the other 20%, with no annual cap. Part A adds a hospital deductible of $1,736 per benefit period in 2026, and that deductible can apply more than once in a year. Medigap caps that exposure.
The California birthday rule
California's standout protection is the annual birthday rule. Under California law, a Medigap policyholder has a 60-day open-enrollment window each year, beginning on their birthday, during which they may switch to a different Medigap policy with the same or lesser benefits than their current policy, with no medical underwriting and no new waiting period, according to the California Department of Insurance. The window applies every year, for life, with no age cap.
The practical value is that you are not locked into your current insurer's price. Medigap benefits inside a letter are identical across companies, but premiums are not, and an insurer's rates can climb faster than a competitor's over time. The birthday rule lets you move your same Plan G (or any equal-or-lesser plan) to a lower-priced carrier once a year without proving you're healthy enough to qualify.
The "equal or lesser benefits" limit is the key constraint. You can move sideways (Plan G to another Plan G) or down to a less generous letter (Plan G to Plan N), but the birthday rule does not let you move up to a more comprehensive plan. Moving up still requires medical underwriting outside a guaranteed-issue window, so a switch from Plan N to Plan G is not protected by the birthday rule.
How to use the birthday rule
The window is short and the timing rules are specific, so plan the switch before your birthday arrives.
- Know your date. The 60-day window begins on your birthday. Shop and compare quotes in the weeks before it so you can act as soon as it opens.
- Confirm the new plan is equal or lesser. Identify your current plan letter, then pick a new policy of the same letter or a less comprehensive one. A Plan G holder can switch to another Plan G or down to Plan N; a Plan N holder can switch to another Plan N or a lesser letter.
- Apply during the window. Submit the application within the 60 days and tell the insurer you are using California's birthday rule. The new insurer cannot apply medical underwriting to the switch.
- Keep the old policy until the new one starts. Don't cancel your existing coverage until the new policy is confirmed and in force, so you're never uninsured.
Because the benefits inside a letter are standardized, the switch changes your premium and insurer, not your coverage, as long as you stay at the same letter. If you move to a lesser letter, your cost-sharing changes to match that letter.
Plan G and Plan N: the common choices
For someone newly eligible for Medicare, the practical choice in California narrows to two plans.
Plan G is the most complete plan still available to people who became eligible on or after January 1, 2020. It covers every gap in Original Medicare except the annual Part B deductible: the Part A hospital deductible, Part A and Part B coinsurance, skilled nursing facility coinsurance, and Part B excess charges. After you pay that one Part B deductible for the year, a Plan G holder generally has no further cost-sharing on Medicare-covered services.
Plan N covers the same major gaps but shifts a little cost back to you. It pays the Part B coinsurance except for a copay of up to $20 for some office visits and up to $50 for emergency-room visits that don't lead to an inpatient admission, and it does not cover Part B excess charges. In exchange, Plan N premiums are usually lower than Plan G premiums.
| Feature | Plan G | Plan N |
|---|---|---|
| Part A hospital deductible | Covered | Covered |
| Part B coinsurance | Covered in full | Covered, minus up to $20 office / $50 ER copays |
| Part B excess charges | Covered | Not covered |
| Annual Part B deductible ($283 in 2026) | You pay it | You pay it |
| Skilled nursing facility coinsurance | Covered | Covered |
| Relative premium | Higher | Lower than Plan G |
Plans C and F are closed to newer enrollees
Plans C and F once covered the annual Part B deductible on top of the other gaps, which made Plan F the most complete plan on the market. Under the Medicare Access and CHIP Reauthorization Act of 2015 (MACRA), any Medigap plan that pays the Part B deductible is closed to people who first became eligible for Medicare on or after January 1, 2020.
The closure works by eligibility date, not purchase date. If you became eligible for Medicare before January 1, 2020, you can still buy or keep Plan C or Plan F in California. If you became eligible on or after that date, those two plans are off the table, which is why Plan G has become the default top-tier choice for newer enrollees: it's identical to Plan F except that you pay the one Part B deductible yourself.
When you can buy or switch in California
California gives you more than one protected window. Three matter most.
- The federal Medigap Open Enrollment Period. This is a one-time, six-month window that begins the first month you're both age 65 or older and enrolled in Medicare Part B. During it, insurers must sell you any Medigap policy they offer at their best available rate regardless of your health, with no medical underwriting. This is the single best time to buy, because you can choose any plan, including moving up to Plan G.
- The annual birthday rule. The 60-day window described above, repeating each year, for switching to an equal-or-lesser plan with no underwriting.
- Federal guaranteed-issue rights. Certain life events, such as losing other coverage or an insurer leaving the market, trigger a federal guaranteed-issue right to buy specific plans without underwriting.
Outside these windows, a California insurer can require medical underwriting and charge more, or decline to sell you a policy, based on your health. That's why the choice between Plan G and Plan N is best made during your six-month open enrollment: if you start on Plan N to save on premiums and later want Plan G, the birthday rule won't cover that move up, and underwriting could make it expensive or impossible.
What Medigap costs and how it's priced in California
Medigap premiums vary widely. The benefits inside a letter are fixed, but the price is not: it depends on the insurer, your age, and in many cases your gender and tobacco use. Nationally, median Plan G premiums run about $150 to $175 a month and Plan N about $125 to $150, though your California quote can fall outside those ranges.
Insurers use one of three pricing methods, which shapes how your premium changes as you age:
- Community-rated policies charge everyone the same premium regardless of age.
- Issue-age-rated policies base your premium on your age when you buy, and that starting point doesn't rise simply because you get older.
- Attained-age-rated policies start lower but increase as you age, so a low first-year quote can climb over time.
Two quotes for the same Plan G can diverge sharply over a decade based on pricing method alone. Ask which method each insurer uses, not just the first-year premium. The birthday rule pairs well with this: if your attained-age policy climbs, the annual window lets you move to a cheaper carrier without underwriting. Note that Medigap does not include prescription drug coverage, so you add a separate Part D plan for that.
Who regulates Medigap in California
Most California Medigap policies are regulated by the California Department of Insurance (CDI), which handles consumer complaints and oversees the insurers that sell these policies. There is one exception: Blue Cross and Blue Shield-branded Medigap plans are regulated by the California Department of Managed Health Care (DMHC) rather than CDI. If you have a complaint or a question about a specific policy, the regulator depends on which company issued it.
Frequently asked questions
California gives Medigap policyholders a 60-day window each year, starting on their birthday, to switch to a Medigap policy of equal or lesser benefits from any insurer, with no medical underwriting. The right repeats every year, for life, with no age cap, per the California Department of Insurance.
No. The birthday rule only lets you switch to a plan with equal or lesser benefits. Moving up to a more comprehensive plan, such as Plan N to Plan G, is not covered and would require medical underwriting outside a guaranteed-issue window. To get Plan G without underwriting, choose it during your six-month open enrollment.
Yes. The birthday rule lets you switch to any insurer that sells the plan you want, not just your current company. Because the benefits inside a plan letter are identical across insurers, this is how Californians move the same coverage to a lower-priced carrier once a year.
Only if you first became eligible for Medicare before January 1, 2020. Plans C and F, which cover the Part B deductible, are closed to anyone who became eligible on or after that date under MACRA. Plan G is the closest available alternative; it's identical to Plan F except that you pay the annual Part B deductible yourself.
It depends on the insurer. Most Medigap policies are regulated by the California Department of Insurance. Blue Cross and Blue Shield-branded plans are regulated by the California Department of Managed Health Care instead.
Learn More
- Medicare plans and coverage in California
- Medigap (Medicare Supplement): how the lettered plans work
- What is Medicare? Parts A, B, C, and D explained
- Original Medicare vs. Medicare Advantage
Find personalized help comparing Medicare Supplement plans in California at brevy.com.
The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.