Medicare Star Ratings

Medicare Star Ratings are the government's yearly quality scorecard for Medicare Advantage and Medicare Part D plans, scored on a scale of 1 to 5 stars. Medicare Advantage is the private-plan alternative to Original Medicare that often bundles hospital, medical, and drug coverage into one plan. Part D is the prescription drug benefit, available as a standalone plan or bundled into an Advantage plan. The Centers for Medicare & Medicaid Services (CMS), the federal agency that regulates Medicare, calculates the ratings from dozens of measures covering preventive care, chronic disease management, member satisfaction, complaints, and customer service.

The rating matters for two practical reasons: it signals how well a plan performs for its members, and it can open an enrollment opportunity you wouldn't otherwise get, since a plan that earns a full 5 stars qualifies for a special enrollment period that lets you switch into it once a year, outside the standard Annual Enrollment Period. Here's what the stars measure, how CMS calculates them, and how to use them when comparing plans.

CMS scores each Medicare Advantage and Part D plan across five broad categories, then combines the results into one overall star rating.

• Staying healthy: whether members get recommended screenings, tests, and vaccines on schedule.
• Managing chronic conditions: how well the plan coordinates care and follow-up for members with ongoing health issues.
• Member experience: results from member satisfaction surveys about the plan overall.
• Member complaints: how often members file complaints with CMS or choose to leave the plan.
• Customer service: how easily members can reach the plan, get accurate information, and resolve problems.

A 5-star rating means excellent performance on these measures. A 1-star rating means poor performance. Most Medicare Advantage and Part D plans land somewhere between 3 and 4.5 stars.

CMS publishes updated star ratings every October on Medicare Plan Finder, ahead of the Annual Enrollment Period. Ratings are recalculated each year, so a plan that earns 5 stars this year can drop to 4 stars, or lower, the next year based on updated performance data.

The rating carries financial weight for insurers too. Medicare Advantage plans that score 4 stars or higher qualify for quality bonus payments from CMS, which can fund extra benefits like reduced premiums or added dental, vision, and hearing coverage. According to CMS, plans that score below 3 stars for three consecutive years receive a low performing icon on Medicare Plan Finder, a flag worth checking before you enroll or renew. Full methodology is published in the CMS Part C and D Star Ratings technical notes.

You can check any Medicare Advantage or Part D plan's current star rating for free using Medicare Plan Finder. Enter your ZIP code, and Plan Finder lists the overall star rating for every plan available in your area, along with the individual category scores described above. If you already have a plan, your annual notice of change, mailed each fall, also lists your plan's current rating alongside next year's rating.

Star ratings are one input, not the whole decision. See our plan comparison framework for how to weigh stars against premium, network, and drug coverage together. Star ratings only apply to Medicare Advantage and Part D, not Medicare Supplement plans. If you're weighing Advantage against a Medigap plan, our Advantage vs. Supplement guide covers that tradeoff, and our turning 65 guide covers enrollment basics if you're new to Medicare.