What are CMS Star Ratings?

If you've spent any time comparing Medicare Advantage plans or Prescription Drug Plans, you've likely encountered the "Star Rating" for a plan. It's one of the most useful — and underutilized — tools available to Medicare beneficiaries. Issued by the Centers for Medicare and Medicaid Services (CMS), the Star Rating is a federally assigned quality score that measures how well Medicare Advantage and Part D plans are actually performing for their members.

CMS collects data from member satisfaction surveys, the plans themselves, and healthcare providers to generate an annual overall performance rating. Plans receive a score from 1 to 5:

• 5-stars: Excellent
• 4-stars: Above Average
• 3-stars: Average
• 2-stars: Below Average
• 1-star: Poor

The system exists to give beneficiaries an objective quality benchmark when comparing plans — and to create accountability incentives for insurers and providers to continuously improve care. These ratings are updated each fall for the following calendar year, which means your plan's rating can change year over year. Checking your plan's current rating annually is a smart habit, especially before the Annual Enrollment Period.

How are CMS Star Ratings Calculated?

Medicare Advantage Star Ratings

1. Member experience: How members rate the health plan overall, including satisfaction with care and the plan's responsiveness.
2. Member complaints and changes: How frequently Medicare identified problems with the plan, how often members filed complaints, and how much the plan's performance has improved — or declined — over time.
3. Customer service: The quality and responsiveness of call center services, as well as how fairly and efficiently the plan handles member appeals.
4. Chronic conditions: How well the plan coordinates care for members with chronic conditions — specifically, how often those members receive the recommended tests and treatments to effectively manage their health.
5. Staying healthy: Whether members have access to preventive services — physical exams, screening tests, vaccinations, and regular check-ups — that help them stay well before problems develop.

Medicare Advantage plans that include prescription drug coverage (MA-PD contracts) are evaluated on up to 44 unique quality and performance measures. MA-only plans (without prescription drug coverage) are rated on up to 32 measures — a meaningful scope of evaluation in either case.

Prescription Drug Plan (PDP) Star Ratings

Standalone Medicare Part D plans receive their own overall Star Rating based on 4 categories and up to 14 individual quality measures:

• Member experience
• Member complaints and changes
• Customer service
• Drug safety and accuracy of pricing: How accurately the plan communicates pricing information and how consistently members with specific medical conditions adhere to recommended drug schedules — a proxy measure for how well the plan is supporting good medication management.

How do I enroll in a 5-star plan?

One of the more valuable — and lesser-known — perks of a 5-star plan designation: if a 5-star Medicare Advantage or Part D plan is available in your area, you can use a Special Enrollment Period to switch into it at any time of the year. Here's how the enrollment windows work:

• Annual Open Enrollment Period (Oct 15 – Dec 7): Available annually for existing Medicare beneficiaries who want to review and switch plans. This is the primary window for most plan changes.
• Special Enrollment Period (Dec 8 – Nov 30 of next calendar year): A unique benefit of 5-star plans — you can switch into a 5-star plan at virtually any point during the year. This window can only be used once per calendar year, so use it strategically if your current plan has declined in quality.

If you're enrolling in Medicare for the first time, you can choose a 5-star plan directly during your Initial Enrollment Period — the 7-month window that begins 3 months before the month of your 65th birthday.

Final Words

CMS Star Ratings aren't the only thing to consider when selecting a Medicare Advantage or Part D plan — premium cost, formulary coverage, provider networks, and additional benefits all matter. But Star Ratings provide a valuable, objective layer of comparison that's easy to overlook when everyone is focused on premium costs alone.

The practical takeaway: check your plan's Star Rating each fall before Annual Enrollment. If your plan has dropped significantly from where it was, that's meaningful information — and if a 5-star plan is available in your area, you have more flexibility to switch than most beneficiaries realize. The majority of Medicare beneficiaries are already enrolled in 4-star or higher plans, but plan quality can shift, and staying aware of your plan's performance is one of the simplest things you can do to protect the quality of your healthcare coverage.