Anyone who has compared Medicare Advantage or Part D prescription drug plans has seen the rows of stars next to each plan’s name. Those stars come from a formal quality rating system run by the Centers for Medicare & Medicaid Services (CMS), the federal agency that oversees the Medicare program. The ratings condense dozens of quality and service measurements into a single score from one to five stars, refreshed every year. Used well, they are one of the more useful shortcuts available when comparing plans; used carelessly, they can be mistaken for a guarantee of a good personal fit. This 2026 guide explains what Medicare star ratings actually measure, when and where they are published, the special enrollment right attached to 5-star plans, and how to fold ratings into a plan comparison sensibly.
What the star rating system is
The star rating system is CMS’s annual report card for private plans that participate in Medicare. Medicare Advantage plans and standalone Part D prescription drug plans each receive an overall rating on a five-star scale, where five stars represents excellent performance and one star represents poor performance, with half-star increments in between. Medicare Advantage plans that include drug coverage are rated on both the health plan side and the drug plan side, combined into one overall score. The ratings apply to the plan contract, which can cover many individual plan options in different counties — a detail worth knowing, because two plans with the same star rating under the same contract can still differ in premiums, networks, and benefits.
What the stars measure
The overall score is built from a large set of individual measures, grouped into a few broad themes. The first is clinical quality: whether members receive recommended screenings, vaccines, and tests, and how well the plan supports management of chronic conditions such as diabetes and high blood pressure. The second is member experience: survey-based measures of how members rate their plan, their ability to get needed care and appointments quickly, and their experience with the plan’s doctors and drug coverage. The third is plan performance and customer service: complaint rates, how many members choose to leave the plan, how the plan handles appeals, and call-center responsiveness. Drug plan ratings add measures around drug pricing accuracy and medication adherence — for example, whether members with certain long-term prescriptions are able to stay on them consistently. Each measure is scored, weighted, and rolled up, so the overall star number reflects a blend of clinical results, member opinion, and administrative performance rather than any single factor.
Where the data comes from
The underlying data comes from several independent streams, which is part of what gives the ratings credibility. Clinical measures draw on standardized quality reporting that plans must submit. Member experience comes largely from national surveys of actual enrollees, conducted using consistent methods across plans. Complaint and disenrollment figures come from Medicare’s own administrative records rather than from the plans. Because the inputs are collected over the prior measurement year and then processed, the ratings always describe recent past performance — a useful indicator, but a trailing one. A plan under new management or with a recently changed network may perform differently than its current stars suggest, in either direction.
When ratings are published
CMS releases updated star ratings each fall, typically in October, timed so that the new scores are visible during the Annual Election Period that runs from October 15 through December 7. The ratings published in fall apply to the following plan year, so the stars shown while shopping for 2026 coverage were released in fall 2025. This annual rhythm means ratings can move from year to year: a plan can gain or lose stars as its measured performance changes, and CMS periodically adjusts which measures are included and how they are weighted. That is one more reason the fall window is a sensible time to re-check a current plan rather than assuming last year’s impression still holds. Plans that perform poorly for several consecutive years are flagged with a low-performance warning icon in the comparison tool, and consistently low-rated contracts can ultimately face removal from the program.
The 5-star Special Enrollment Period
One consequential rule attaches to top-rated plans. If a Medicare Advantage plan or Part D plan with an overall 5-star rating is available in your service area, you can switch into it outside the normal enrollment calendar, using a Special Enrollment Period that runs for most of the year, from early December through the end of November of the plan year. This 5-star Special Enrollment Period can generally be used once per year, and the switch takes effect the month after the plan receives the request. In practice, 5-star plans are not available everywhere, so the first step is simply checking whether one operates in your county. For someone unhappy with a current plan mid-year, this is one of the few paths to a change that does not require waiting for fall, though the usual cautions apply: moving from Medicare Advantage back and forth can affect drug coverage timing and does not by itself create a right to buy a Medigap policy without underwriting.
How to use ratings when comparing plans
Star ratings work best as a screen, not a verdict. A practical approach is to use them to sort the field: ratings around four stars and above indicate a plan that has performed well across quality, member experience, and service measures, while a low-performance icon is a signal to investigate further before enrolling. From there, the factors the stars cannot see take over. The ratings say nothing about whether your doctors are in a plan’s network, whether your prescriptions are on its formulary and at what tier, how its copayments are structured for the services you actually use, or what its premium is. A 5-star plan whose network excludes your specialists may serve you worse than a 4-star plan built around your existing providers. It can also help to look past the overall number: the plan comparison tool lets you view individual measure categories, so someone who cares most about customer service or drug-related measures can check those specific scores directly.
What star ratings cannot tell you
A few limitations are worth stating plainly. Ratings are contract-level averages, so they can mask variation between a plan’s counties or between individual plan options under the same contract. They are backward-looking, describing a prior measurement period. They do not measure affordability for your particular mix of services and medications, and they are not a prediction of how any individual claim or prior-authorization request will be handled. None of this makes the ratings unreliable — it makes them one input among several. Treating a star score as a starting filter, then verifying network, formulary, and cost-sharing fit, uses the system the way it was designed to be used.
How to check star ratings for plans in your area
Current star ratings for every Medicare Advantage and Part D plan are published in the official plan comparison tool at Medicare.gov, where you can view overall scores and drill into individual measure categories for plans in your ZIP code. Background on how the rating system is constructed, including the technical measure lists, is available from CMS.gov. For free, unbiased help interpreting ratings alongside networks and drug coverage, a State Health Insurance Assistance Program counselor or a licensed insurance agent can walk through the comparison with you.
Final thoughts
Medicare star ratings compress a plan’s measured performance — clinical quality, member experience, and customer service — into a single annual score, refreshed each fall in time for open enrollment. They are genuinely useful for narrowing a crowded field, and the 5-star Special Enrollment Period gives top-rated plans a practical significance beyond bragging rights. But stars measure how a plan has performed for its members on average, not how it will fit you. Check the rating, then check your doctors, your medications, and the cost-sharing structure, and use Medicare.gov or a SHIP counselor to confirm the details before making a change.
Disclaimer
This article is for general informational purposes only and is not medical, financial, legal, or enrollment advice. This site is not affiliated with or endorsed by Medicare, the Centers for Medicare & Medicaid Services, or any government agency. Star ratings, rating methods, plan availability, and enrollment rules can change each year and vary by location. Always verify current information at Medicare.gov, and consider speaking with a licensed insurance agent or SHIP counselor before making enrollment decisions.