INSURING YOUR TRUST

Medicare Supplement (Medigap) Insurance: The Complete California Guide

Original Medicare is powerful — but it was never designed to cover everything. When you use Medicare Part A and Part B, you're responsible for deductibles, copayments, and coinsurance that can add up quickly. And unlike most private insurance, Original Medicare has no annual out-of-pocket maximum. A serious illness or extended hospital stay can expose you to tens of thousands of dollars in costs that Medicare simply doesn't cover.

Medicare Supplement insurance — officially called Medigap — exists specifically to fill those gaps.

This page explains how Medigap works, which plans are available in California, how to compare them honestly, and why California residents have a unique advantage when it comes to shopping for coverage. When you're ready to look at actual plans and pricing for your situation, Peter Joseph and the team at Joseph Insurance Broker are here to help — at no cost to you.

What Is Medigap Insurance?

Medigap is private health insurance sold by licensed insurance companies to people who are enrolled in Original Medicare (Parts A and B). It is designed to pay for costs that Original Medicare leaves behind — including the Part A hospital deductible, Part B coinsurance, skilled nursing facility coinsurance, and in some plans, even Part B excess charges and foreign travel emergency care.

The name "Medigap" is straightforward: it fills the gaps in Medicare coverage.

A few foundational rules govern how Medigap works:

You must be enrolled in Original Medicare (Parts A and B) to purchase a Medigap policy. Medigap is not compatible with Medicare Advantage. If you're on a Medicare Advantage plan, you cannot simultaneously carry a Medigap policy.

Medigap policies cover one person. Unlike some insurance products, a Medigap policy covers only the policyholder. If both you and your spouse want Medigap coverage, you each need your own separate policy.

Medigap policies are renewable for life as long as you pay your premium. An insurer cannot cancel your Medigap policy because of your health — as long as you continue paying premiums, your coverage is guaranteed to continue.

Medigap does not include prescription drug coverage. If you choose Original Medicare plus a Medigap policy, you'll also need to enroll in a standalone Part D prescription drug plan to cover your medications.

How Medigap Works in Practice

When you receive medical care under Original Medicare, the billing process works in layers. Medicare processes the claim first and pays its share. Then your Medigap plan pays its share of the remaining balance, according to the benefits of your specific plan.

In many cases — particularly with the most comprehensive Medigap plans — you end up with little to no out-of-pocket cost for covered services after both Medicare and your Medigap plan have paid. This predictability is the defining appeal of Medigap for people who want financial certainty in their healthcare spending.

Consider a scenario where you're hospitalized for five days. Original Medicare Part A covers the stay but leaves you with a deductible of over $1,600 (2026 amount) plus daily coinsurance starting on day 61. A comprehensive Medigap plan covers that deductible entirely, eliminating the surprise bill. For someone managing a serious chronic condition or anticipating surgery, that protection is not a luxury — it's a financial necessity.

Medigap Plans Available in California

Federal law standardizes Medigap plans by letter, which means a Plan G from Humana covers exactly the same benefits as a Plan G from Aetna, Blue Shield, or any other carrier. The only differences between carriers for the same plan letter are the monthly premium, the company's financial stability, and the quality of their customer service.

This standardization is enormously consumer-friendly. It means you can compare plans across carriers purely on price and service quality, without trying to decode differences in benefit structures.

In California, the following Medigap plan letters are currently available to new enrollees:

Plan G — The Most Comprehensive Option for New Enrollees

Plan G is the most popular Medigap plan for people newly eligible for Medicare, and for good reason. It covers virtually everything Original Medicare doesn't, including the Part A deductible, Part A coinsurance and hospital costs up to 365 days after Medicare benefits are exhausted, Part B coinsurance and copayments, the first three pints of blood, skilled nursing facility coinsurance, Part B excess charges, and foreign travel emergency care (up to plan limits).

The only cost Plan G does not cover is the Part B deductible — which in 2026 is $257 per year. Beyond that single annual deductible, most Plan G enrollees have predictable, minimal out-of-pocket costs for Medicare-covered services.

For people who want the closest thing to comprehensive coverage with the freedom to see any Medicare-accepting provider in the country, Plan G is the benchmark.

Plan N — Strong Coverage at a Lower Premium

Plan N covers most of the same benefits as Plan G, with two key differences. First, Plan N does not cover Part B excess charges — the amount a provider can charge above Medicare's approved amount when they don't accept Medicare assignment. Second, Plan N requires copayments of up to $20 for office visits and up to $50 for emergency room visits that don't result in inpatient admission.

In exchange for accepting those cost-sharing elements, Plan N enrollees typically pay a meaningfully lower monthly premium than Plan G enrollees. For people who are generally healthy, see their doctors infrequently, and want to keep premiums down while still having strong catastrophic protection, Plan N can be an excellent value.

The key consideration with Plan N is the excess charge exposure. In California, most providers accept Medicare assignment, making excess charges relatively rare — but it's worth discussing with your broker whether your specific providers are assignment-accepting before choosing Plan N over Plan G.

Plan A — Basic Benefits Only

Plan A is the most basic Medigap plan, covering only core benefits: Part A coinsurance and hospital costs, Part B coinsurance and copayments, the first three pints of blood, and hospice care coinsurance. It does not cover the Part A deductible, skilled nursing facility coinsurance, or foreign travel emergencies.

For most people, Plan A provides insufficient protection relative to its cost. Plans G and N offer significantly broader coverage and are almost always the better choice unless premium minimization is the absolute top priority.

Plan B

Plan B adds coverage for the Part A deductible on top of the Plan A core benefits. It remains a fairly limited plan compared to G and N, and is chosen infrequently.

Plan D

Plan D covers the Part A deductible, skilled nursing facility coinsurance, and foreign travel emergencies, but does not cover Part B excess charges. It occupies a middle ground between Plan N and Plan G that relatively few enrollees choose.

High-Deductible Plan G (HDG)

High-Deductible Plan G provides the same benefits as standard Plan G but requires you to pay a high annual deductible — $2,870 in 2026 — before the plan begins paying. In exchange, the monthly premium is significantly lower, often dramatically so.

High-Deductible Plan G can be an attractive option for people who are healthy, want to keep premiums low, and are comfortable absorbing a higher deductible in exchange for long-term premium savings. It functions somewhat like a high-deductible health plan in the commercial market — you're essentially self-insuring for smaller costs while protecting yourself against catastrophic exposure above the deductible.

Plan K and Plan L

Plans K and L are cost-sharing plans that cover a percentage of benefits rather than the full benefit amounts. Plan K covers 50% of most benefits and has a lower out-of-pocket maximum; Plan L covers 75%. These plans are less commonly sold because most people find the uncertainty of percentage-based cost sharing less appealing than the predictability of Plans G and N.

What Medigap Does Not Cover

Medigap is powerful, but it has clear limits. No Medigap plan covers:

• Prescription drugs. You need a standalone Part D plan for medication coverage.
• Dental care. Routine dental work, cleanings, and major dental procedures are not covered.
• Vision care. Eye exams, glasses, and contact lenses are not included.
• Hearing aids. Medigap does not cover hearing exams or hearing devices.
• Long-term care. Custodial care in a nursing home or assisted living facility is not a Medigap benefit.
• Private-duty nursing.
• Cosmetic surgery.

For dental, vision, and hearing coverage alongside a Medigap policy, you'll need to purchase standalone plans or consider whether a Medicare Advantage plan — which often bundles these benefits — better fits your needs overall. This is a trade-off worth discussing carefully, particularly for people who have significant dental needs.

Medigap vs. Medicare Advantage: The Core Trade-Off

This is the central question for most people new to Medicare, and there is no universally correct answer. Here is the honest comparison:

Choose Medigap if you prioritize:

• Unrestricted access to any doctor, specialist, or hospital nationwide that accepts Medicare — no network, no referrals
• Predictable, minimal out-of-pocket costs regardless of how much care you use
• The ability to travel or live in multiple states without coverage concerns
• Stability — Medigap benefits are standardized and don't change year to year the way Medicare Advantage plans do

Choose Medicare Advantage if you prioritize:

• Lower or $0 monthly premiums
• Built-in extra benefits like dental, vision, hearing, and fitness
• Prescription drug coverage bundled into a single plan
• Access to care coordination programs offered by many Advantage plans

The real tension is this: Medigap costs more month to month but protects you better when you actually need significant care. Medicare Advantage costs less month to month but exposes you to more variable out-of-pocket costs and network restrictions when you need care most.

For people in excellent health who are comfortable managing those variables, Medicare Advantage can be the right financial choice. For people with chronic conditions, complex medical needs, or strong preferences about which doctors and hospitals they use, Medigap frequently provides better overall value — even at a higher monthly premium.

There's also a timing consideration. Medigap underwriting rules mean that the best time to enroll is during your Medigap Open Enrollment Period — the 6-month window that begins when you are both 65 and enrolled in Part B. During this window, no insurer can deny you coverage or charge you more based on your health history. Once that window closes, applying for Medigap in most states requires medical underwriting, and pre-existing conditions can result in higher premiums or denial.

California, however, offers important additional protections — which brings us to one of the most valuable things a California resident can know about Medigap.

California's Birthday Rule: A Critical Advantage for State Residents

California is one of a small number of states including Idaho, Illinois, Kentucky, Louisiana, Maryland, Nevada, Oklahoma, Oregon, Utah, Virginia, and Wyoming, with Delaware and Indiana adding rules in 2026. 

that provides Medigap protections beyond federal law, and the most important of these is the Birthday Rule.

Under California's Birthday Rule, every Medigap policyholder has a 60-day window each year — beginning on their birthday — during which they can switch to any Medigap plan offered by any carrier with equal or lesser benefits than their current plan, without medical underwriting. This means an insurer cannot deny your application, ask about your health history, or charge you a higher premium based on pre-existing conditions during that window.

The practical implications are significant. In most states, once you're past your initial Open Enrollment Period, you're effectively locked into your Medigap plan because switching requires passing medical underwriting. In California, you have an annual opportunity to shop for lower premiums — which tend to increase as you age — and switch carriers without health risk.

This means California residents should review their Medigap premiums every year around their birthday. If another carrier is offering the same Plan G benefits at a lower price, the Birthday Rule gives you a guaranteed right to make that switch. Over a decade of retirement, those annual savings can be substantial.

One important limitation: the Birthday Rule only allows you to switch to a plan with equal or lesser benefits. You cannot use the Birthday Rule to upgrade from Plan N to Plan G, for example. But you can switch from Plan G with one carrier to Plan G with a less expensive carrier — which is the most common and valuable use case.

How Medigap Premiums Are Calculated

Not all Medigap carriers price their plans the same way. Understanding the pricing methodology helps you evaluate long-term cost, not just the initial premium.

Community-rated pricing: Every enrollee pays the same premium regardless of age. Younger enrollees pay more initially but face fewer automatic increases as they get older. Community-rated plans tend to offer better long-term value for people who enroll at 65 and plan to keep the policy for many years.

Issue-age-rated pricing: Your premium is based on the age at which you first enrolled. It doesn't increase simply because you get older, but it may increase due to inflation and other factors. Enrolling younger means locking in a lower base rate.

Attained-age-rated pricing: Your premium increases as you age, in addition to any general rate increases. These plans often start with the lowest premiums but can become significantly more expensive over time. Many people are surprised to find their Medigap premium has nearly doubled a decade into retirement.

California allows all three pricing methods, and the method used by a carrier isn't always prominently disclosed. This is one of the reasons working with an independent broker — who can show you the pricing methodology alongside the current premium — is so valuable. A plan that looks cheapest at 65 may not be cheapest at 75.

The Enrollment Process: Step by Step

Enrolling in a Medigap plan is simpler than many people expect, particularly during your Open Enrollment Period.

Step 1: Confirm you are enrolled in both Medicare Part A and Part B. Medigap requires both.

Step 2: Identify which plan letter is right for your needs and budget. For most new enrollees in California, this comes down to Plan G vs. Plan N vs. High-Deductible Plan G.

Step 3: Compare premiums across carriers for your chosen plan letter. Because benefits are standardized, you're comparing apples to apples — the only variables are premium, pricing methodology, carrier financial strength, and customer service reputation.

Step 4: Apply for your chosen plan. During your Open Enrollment Period, this is a straightforward process with no medical questions. Outside of that window, in most states you'll answer health questions — but California's Birthday Rule gives you an annual underwriting-free window.

Step 5: Enroll in a standalone Part D plan for prescription drug coverage, since Medigap does not include drug benefits.

Step 6: Review your coverage annually — especially around your birthday, when California's Birthday Rule gives you the opportunity to compare premiums and switch if you find better pricing.

Why Working With an Independent Broker Matters for Medigap

Because Medigap benefits are standardized by plan letter, the entire value of working with a broker lies in their ability to compare premiums, explain pricing methodologies, and give you honest guidance about which carriers have strong service reputations in your area.

A captive agent who works for a single carrier can only show you that carrier's plans. An independent broker like Peter Joseph works with all major Medigap carriers in California — including Aetna, Anthem Blue Cross, Blue Shield of California, Cigna, Humana, Mutual of Omaha, United American, and others — and can present a genuine side-by-side comparison based on your specific zip code, age, and plan preference.

Just as importantly, an independent broker can help you understand the long-term pricing picture — not just today's premium. A plan that starts $30/month cheaper but uses attained-age pricing may cost significantly more over a decade than a plan that starts slightly higher with community-rated pricing.

Peter Joseph has been helping California residents navigate this decision for nearly a decade. He has been voted Best Insurance Broker in Chino Valley three years running, recognized as a Top Broker in the Inland Empire, and selected as one of the Top 50 Under 50 by NYC Journal — not because he pushes any particular plan, but because he takes the time to explain the trade-offs honestly and help clients make decisions they feel confident about.

This service costs you nothing. Brokers are compensated by carriers, not by clients.

Frequently Asked Questions

Q: What is the best Medigap plan in California? For most new Medicare enrollees in California, Plan G is the most comprehensive and most popular choice. It covers virtually all Medicare cost-sharing except the annual Part B deductible ($257 in 2026). Plan N is a strong alternative for healthier individuals who want lower premiums and are comfortable with modest copays. The "best" plan depends on your health, your doctors, your budget, and how you weigh premium cost against out-of-pocket exposure.

Q: Can I be denied a Medigap plan because of a pre-existing condition? During your 6-month Medigap Open Enrollment Period — which begins when you are both 65 and enrolled in Part B — insurers cannot deny you or charge you more based on health. Outside of that window, insurers in most states can use medical underwriting. California's Birthday Rule provides an additional annual underwriting-free window, but it only allows switching to a plan with equal or lesser benefits.

Q: How much does Medigap cost in California? Premiums vary significantly based on your age, zip code, the plan letter you choose, the carrier, and the pricing methodology used. In the Inland Empire, Plan G premiums for a 65-year-old typically range from approximately $100 to $200/month depending on the carrier and pricing method. We can pull exact quotes for your specific situation at no cost.

Q: Can I have both a Medigap plan and a Medicare Advantage plan? No. Medigap and Medicare Advantage are mutually exclusive. Medigap is designed to supplement Original Medicare (Parts A and B). If you're enrolled in Medicare Advantage, you are not on Original Medicare for coverage purposes, and a Medigap policy would provide no benefit. Carriers are prohibited from selling you a Medigap policy if they know you're enrolled in Medicare Advantage.

Q: Does Medigap cover dental, vision, and hearing? No. Standard Medigap plans do not cover dental, vision, or hearing. If these benefits are important to you, you can purchase standalone dental and vision plans separately, or weigh whether a Medicare Advantage plan — which often bundles these benefits — better fits your overall needs.

Q: What happens to my Medigap plan if I move to another state? Medigap policies are portable — your coverage travels with you. However, premiums are based on your state of residence, so your premium may be re-rated if you move to a different state. You also gain the consumer protections of your new state, which may differ from California's Birthday Rule.

Q: When is the right time to switch from Medicare Advantage to Medigap? The best time to switch is during your initial Open Enrollment Period when you first go on Medicare — before you've accumulated any health history that could affect underwriting. If you're already on Medicare Advantage and want to switch to Medigap, California's Birthday Rule provides an annual underwriting-free window, but it requires you to already have a Medigap policy in place (you're switching between Medigap carriers, not switching from Advantage to Medigap). Switching from Medicare Advantage to Original Medicare plus Medigap outside of a guaranteed issue period typically requires passing medical underwriting in most states — another reason to think carefully about your initial choice.

Ready to Find the Right Medigap Plan?

Choosing a Medigap plan is one of the most important financial decisions you'll make as you enter Medicare. The right plan protects you from unpredictable healthcare costs for the rest of your life. The wrong plan — or the right plan from a carrier using aggressive attained-age pricing — can cost you significantly more than necessary over time.

Peter Joseph has helped hundreds of California residents find Medigap coverage that fits their health needs, their budget, and their long-term financial picture. He represents all major carriers in California and will show you a genuine, honest comparison — not a pitch for any single insurer.

Call (909) 217-2630 to speak with Peter directly, or book a free consultation online at a time that works for you. We serve clients throughout Chino Hills, the Inland Empire, and across 30+ states — by phone, video, or in person.

Book a Free Medigap Consultation → Compare Medigap vs. Medicare Advantage → Compare Medicare Supplement Plans Side by Side → See If You're Eligible for Medicare → Attend a Free Medicare 101 Seminar →