Every year, as the Annual Enrollment Period (AEP) approaches on October 15, Medicare Advantage advertising fills up with phrases like 'a 4.5-star plan' or '5-star rated,' but rarely explains what that number actually means. This guide does not repeat the general Medicare enrollment dates we cover elsewhere, but instead explains specifically what Star Ratings are, what they measure, why they matter when choosing a plan, and what to check beyond the rating before deciding.
What the CMS Star Rating system is
CMS, the federal agency that oversees Medicare, rates every Medicare Advantage plan and every standalone Part D plan on a scale of 1 to 5 stars, in half-point increments. The rating is published every fall on Medicare.gov and reflects the plan's performance over the prior year, not a promise about the future. A plan can have a different rating each year, so the number you see in October 2026 may not match what it had in 2025.
What the stars actually measure
The rating combines dozens of measures grouped into several broad categories: preventive care quality, such as vaccinations and cancer screenings; chronic disease management, such as diabetes or blood pressure control; member experience, measured through satisfaction surveys; complaints and problems filed with Medicare; and the plan's customer service, including how quickly the plan responds to calls and appeals. Part D plans also include specific measures on medication safety and pricing accuracy.
In short, the rating does not measure a single aspect of the plan, but a weighted average of how it performs in practice: how well it keeps its members healthy and how well it treats them when they call with a problem.
Availability, cost, benefits, and eligibility vary by person, product, contract, and insurance company, as well as by your service area. Guarantees are subject to the claims-paying ability of the issuing insurance company. Karla Arámburo is not affiliated with or endorsed by Medicare or the federal government.
Why the rating matters when choosing a plan
The rating is a useful indicator of how well-run a plan is and how satisfied its current members are, something the monthly premium alone does not tell you. A plan with a consistently low rating, 2 or 2.5 stars for several years running, can signal recurring service problems, slow authorizations, or a high complaint rate, even if its premium looks attractive.
CMS can even remove a plan from the market that stays below 3 stars for three consecutive years, so a history of low ratings also carries some risk that the plan will not exist much longer.
The 5-star enrollment bonus
If a Medicare Advantage or Part D plan available in your ZIP code earns 5 stars, you have access to a 5-Star Special Enrollment Period, running from December 8 through November 30 of the following year. Within that window you can switch to that 5-star plan once, without waiting for the October-December AEP or any other special period. It is a little-known exception to Medicare's normal enrollment rules.
Very few plans in Southern California reach 5 stars every year, so this bonus is not always available in your area, but it is worth checking before assuming you have to wait until October to make a change.
How to look up your plan's rating or one you are considering
The most direct way is to go to Medicare.gov, use the Medicare Plan Finder, enter your ZIP code and your medication list, and review the star rating shown next to each plan available in your area. You can also call a plan directly and ask for its current rating, though Medicare's official site is always the most reliable and up-to-date source.
What to check beyond the rating before deciding
| Beyond the rating, check | Why it matters |
|---|---|
| Doctor network | A 5-star plan is no help if your doctor or specialist is not in the network |
| Drug formulary | The rating does not guarantee your specific prescriptions are priced well under that plan |
| Maximum out-of-pocket cost | Two plans with the same rating can have very different annual spending limits |
| Extra benefits | Dental, vision, and transportation vary widely between plans with similar ratings |
In other words, the rating is a good starting point for ruling out plans with a history of poor service, but the final decision should be based on how that specific plan covers your doctor network, your medications, and your real budget.
If you are not yet clear on how Medicare Advantage compares to Medigap in general, review our Medicare Advantage vs. Medigap comparison, and to understand the exact 2026 AEP, Open Enrollment, and other special period dates, check our Medicare 2026 enrollment dates guide.
Free bilingual help before October 15
I am Karla Arámburo, an independent, bilingual insurance agent licensed to serve families in Orange, Los Angeles, San Diego, and Riverside counties, including cities like San Diego, Riverside, and La Quinta. I review your plan's current rating and other options in your ZIP code with you, along with your doctor network and the real cost of your medications, before AEP starts on October 15, 2026, in Spanish or English, at no cost to you.
You can call or text (619) 321-8733 or schedule a free consultation before AEP begins. This page is general education, not individualized advice or a product recommendation.
Frequently asked questions
What exactly are Medicare Star Ratings?
They are a 1-to-5 star rating that CMS (the Centers for Medicare and Medicaid Services) assigns each year to Medicare Advantage and Part D plans, based on dozens of measures of quality, service, and patient experience. Five stars is the highest possible rating.
How often do the ratings change?
CMS publishes new ratings each fall, usually in October, right before the Annual Enrollment Period (AEP). A plan that had 4.5 stars last year can go up, down, or stay the same, so it is worth checking the current rating each year rather than relying on what you remember.
Is a 5-star plan automatically the best one for me?
Not necessarily. The rating measures overall plan quality and service, but it does not tell you whether your specific doctor is in the network, whether your medications are on the formulary at a good price, or whether the out-of-pocket cost fits your budget. A 4-star plan that does cover your doctor can be a better fit than a 5-star plan that does not.
What is the 5-star Special Enrollment Period?
It is a special window, from December 8 through November 30 of the following year, that lets you switch once to a 5-star-rated Medicare Advantage or Part D plan available in your ZIP code, outside the normal Annual Enrollment Period.
How do I look up the rating of a specific plan?
The official tool is the Medicare Plan Finder at Medicare.gov, where you enter your ZIP code and see the star rating next to each plan available in your area. I can also look up and compare that information with you directly during a consultation.
Does the rating include member complaints?
Yes. Part of the rating comes from the rate of complaints filed with Medicare, the percentage of members who voluntarily leave the plan each year, and satisfaction surveys of members themselves, not just clinical measures.
Can you help me compare ratings before October 15?
Yes. I review your plan's current rating and other options available in your ZIP code with you, along with your doctor network and the real cost of your medications, before AEP starts on October 15, at no cost to you.