Medicare Supplement Plans in California: What to Know for 2027

In California, Medigap is the route many people take to make their Medicare costs predictable. This 2027 guide lays out the standardized plans, what each helps pay, and your enrollment rights across California, in straightforward language.

Medicare coverage isn't uniform across California. Plans are approved county by county, so what's on offer can shift from one neighboring area to the next — the reason we break the state down by city below.

About 52% across California have chosen Medicare Advantage over Original Medicare, though that share swings a lot depending on where you live.

You'll find the carriers operating in California, how the parts of Medicare relate, the 2027 figures everyone shares, when you can enroll, where to get unbiased help, and a guide for every city. Educational only, with no rankings.

What Medigap does — and doesn't — cover

Think of Medigap as the layer that sits on top of Original Medicare to absorb the costs it leaves you: the deductibles, the 20% coinsurance, the copays that otherwise have no annual ceiling.

The catch that trips people up is that these plans are federally standardized — a Plan G from one insurer covers exactly what a Plan G from another does. So the letter defines the benefits, and price and service are what separate companies. Medigap doesn't include drug coverage, so most people in California pair it with a stand-alone Part D plan.

Below we break down what each standardized plan covers and the enrollment rights that matter most in California. It's a framework, not a ranking — and we don't quote premiums.

What Medicare costs in 2027

It helps to separate the costs everyone shares from the costs that vary by plan. The program-level numbers here are set nationally — the same whether you're in a big city or a rural county.

Part B premium. Most people pay the standard Part B premium of $202.90 a month in 2026 (2026 amount; 2027 figure will be posted when CMS releases it). Part A is premium-free for most people who worked and paid Medicare taxes long enough.

Part D drug costs. In 2027, a Part D plan's yearly deductible can be no more than $700, and a $2,400 cap limits what you pay out of pocket for covered prescriptions across the year — a real change for anyone with high drug costs.

Higher earners pay more for Parts B and D through an income-related adjustment called IRMAA, which for 2026 starts above $109,000 in annual income for an individual and is based on your 2024 tax return. Most people fall below that line and pay the standard amounts. The 2027 brackets will be posted when CMS releases them.

Plan-specific costs. What an individual plan charges — its premium, deductible, copays, and what it covers — varies by plan and changes yearly. We don't publish those figures or rank plans; Medicare's Plan Finder shows the current details for your situation, and a licensed agent can walk you through them.

Your Medicare enrollment calendar

The dates that follow are set federally, so they don't change from state to state — only your personal timing does.

It starts with your Initial Enrollment Period — the 7-month window around your 65th birthday month — the window around turning 65 when you first sign up. Missing it can mean late penalties that stick around, so it's the one not to sleep on.

After that, the big recurring window is the Annual Enrollment Period (Open Enrollment), October 15 – December 7, when anyone can join, switch, or drop an Advantage or Part D plan for a January 1 start. And if you're already in an Advantage plan, the Medicare Advantage Open Enrollment (January 1 – March 31) gives you one more chance to change course.

Life events — a move, a loss of other coverage — can also trigger a Special Enrollment Period. The calendar below shows the whole year at a glance.

Where to get free, unbiased help near California

Good Medicare help exists and it's free — you don't have to figure this out solo or pay for guidance.

For official specifics and the Plan Finder tool, go straight to Medicare.gov or 1-800-MEDICARE (TTY 1-877-486-2048). And a licensed agent can compare options and handle the paperwork with you.

One note on who we are: MyMedicarePlans.org is an independent, privately owned educational resource — not Medicare, not a government agency, and not affiliated with one. Our job is to help you get oriented, then hand you off to the official sources and licensed professionals for plan decisions.

California cities

Pick your city for the county-level picture, the companies active in your area, and local guides: