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Medicare Advantage star ratings are CMS’s annual ratings of the quality of care and services delivered by Medicare Advantage and Part D contracts. CMS rates individual measures from one to five stars, then combines eligible measure ratings into Part C and Part D summary ratings and, where drug coverage is included, an overall MA-PD rating. The result depends not only on a contract’s measured performance, but also on measure weights, annual performance cut points, contract type, and adjustments to the calculation.
The current 2027 ratings were published on October 8, 2026. They apply to contract year 2027 and use data primarily from measurement year 2025. Here is how to follow the calculation, which measures carry the most weight, and what a change in a plan’s rating can—and cannot—tell you.
What a Medicare Advantage star rating represents
The Centers for Medicare & Medicaid Services (CMS) rates contracts on measures of care and service, rather than assigning a star count based on a single test or a plan’s benefits. The measures draw on sources that include CAHPS surveys, the Health Outcomes Survey (HOS), HEDIS, Part C and Part D reporting requirements, and data validation. The data source and scoring rules differ by measure.
CMS first rates individual measures. It then uses the eligible measure ratings to calculate a Part C summary rating and, for contracts that include Part D drug coverage, a Part D summary rating. An MA-PD contract receives an overall rating as well. The overall number therefore condenses results from multiple measures and categories; it does not describe every part of a member’s experience or predict the health outcome an individual person will have.
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The number of measures depends on the contract type. For the 2027 ratings, MA-PD contracts cover up to 43 unique measures, MA-only contracts up to 32, and standalone Part D plans up to 13. “Up to” matters: the measure set and minimum measure requirements vary by contract type, and a contract does not necessarily have a rating for every possible measure.
How CMS calculates the ratings
1. CMS scores each measure from its underlying data
CMS begins with data for each applicable measure. Depending on the measure, that may include survey responses, clinical or administrative data, plan-reported information, or validated reporting. A measure’s score is not automatically its star rating: CMS converts the score using the method specified for that measure.
2. CMS converts measure scores into one-to-five-star ratings
For most measures, CMS uses clustering across contract scores to establish four cut points, creating five performance bands. In the 2027 methodology, CMS removes Tukey outer-fence outliers for non-CAHPS measures and uses mean resampling to estimate cut points. The cut points determine which star band a score falls into.
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Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallCAHPS measures use a different approach based on relative score distributions and significance tests, including checks related to score reliability. It would be inaccurate to assume that every measure is assigned stars using the same clustering procedure.
CMS also applies guardrails to limit some year-to-year movement in cut points. For measures on a 0–100 scale, the stated guardrail limits movement to at most five percentage points. A guardrail can moderate a change; it does not freeze a cut point or guarantee that a measure’s star rating will stay the same.
3. CMS combines rated measures using weights
For the summary and overall calculations, CMS multiplies each rated measure’s star rating by its weight, adds those weighted values, and divides by the total weights for measures with ratings. A weight of 3 contributes three times as much as a weight of 1. Measures without a rating are excluded from this weighted-average calculation.
For example, imagine a simplified calculation with one four-star measure weighted 3 and one three-star measure weighted 1. The weighted average is (4 × 3 + 3 × 1) ÷ (3 + 1), or 3.75. That is only an illustration of the arithmetic, not a CMS result or an estimate of a real plan’s rating. Actual calculations include the applicable measures, contract-specific rules, and adjustments; summary and overall ratings use half-star increments.
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4. CMS applies additional rules before publishing
The weighted average is not the only rule in the final calculation. CMS’s methodology also includes reward-factor, Categorical Adjustment Index, improvement-measure, and rounding rules. Contract types have minimum measure requirements. Those rules, along with the contract’s applicable measure set and the ratings assigned to those measures, help determine the published summary and overall results. The calculation should not be reduced to averaging every displayed measure or treating all measures as equally important.
Which measures affect a plan’s score the most?
For 2027, the broad weighting order is: improvement measures carry the most weight; outcomes and intermediate outcomes come next; patient experience, complaints, and access measures follow; and process measures carry the least weight. The 2027 Attachment G weights are 5 for improvement measures, generally 3 for outcomes and intermediate outcomes, 2 for patient experience/complaints and access, and 1 for process measures. Check the individual measure because measure-specific rules and exceptions can apply.
| 2027 measure category or example | Weight | Examples |
|---|---|---|
| Improvement | 5 | Health Plan Quality Improvement (Part C); Drug Plan Quality Improvement (Part D) |
| Outcomes and intermediate outcomes | Generally 3 | Improving or Maintaining Physical Health; Improving or Maintaining Mental Health; Diabetes Care—Blood Sugar Controlled; Controlling Blood Pressure; Plan All-Cause Readmissions; three medication-adherence measures |
| Patient experience, complaints, and access | 2 | Getting Needed Care; Rating of Health Plan; Complaints about the Health Plan; appeals measures |
| Process | 1 | Breast Cancer Screening; Annual Flu Vaccine; Concurrent Use of Opioids and Benzodiazepines; Polypharmacy: Use of Multiple Anticholinergic Medications in Older Adults |
The table gives the broad 2027 categories and named examples; it is not a substitute for the individual measure’s applicable rules. A weight says how much a rated measure contributes to the applicable weighted average, not how important that service is to a particular beneficiary. It also does not mean a plan’s performance on one measure alone determines its overall rating.
Two outcome measures—Improving or Maintaining Physical Health and Improving or Maintaining Mental Health—changed from weight 1 in 2026 to weight 3 in 2027 after substantive specification changes. Consequently, their influence on the aggregate calculation increased even if a plan’s performance on either measure did not change. When comparing ratings across years, a changed weight can matter separately from a changed measure score.
What changed in the 2027 measure set?
CMS’s 2027 ratings include several measure-set and specification changes. These affect what is rated, how some measures are defined, or how much some results count; they are distinct from a plan simply performing better or worse on an unchanged measure.
- Two Part D process measures were added: Concurrent Use of Opioids and Benzodiazepines and Polypharmacy: Use of Multiple Anticholinergic Medications in Older Adults. Each has weight 1.
- Care for Older Adults—Functional Status Assessment returned after a substantive specification change.
- The respecified Colorectal Cancer Screening measure replaced the legacy measure.
- Improving or Maintaining Physical Health and Improving or Maintaining Mental Health increased from weight 1 to weight 3 after substantive specification changes.
- Medication Therapy Management Program Completion Rate for Comprehensive Medication Review moved to the display page for measurement years 2025 and 2026. It is scheduled to return as a new measure for 2029 ratings, based on measurement year 2027.
- Care for Older Adults—Pain Assessment and Medication Reconciliation Post-Discharge were retired from the ratings.
These changes mean that a year-to-year comparison is not always a like-for-like comparison of the same measures under the same rules. A missing or newly appearing measure can reflect a change in the rating program rather than a sudden change in a plan’s underlying service.
Why a plan’s star rating can change from year to year
CMS recalculates measure cut points each year based on performance during the measurement period. As CMS states in its October 8, 2026 fact sheet, “The cut points are recalculated each year based on performance during the measurement period.” Therefore, a plan’s measure star can change for several different reasons:
- The plan’s measured performance changed. A different measure score may place the contract in a different performance band.
- The distribution of scores across contracts changed. Because cut points are recalculated, a contract’s relative position can matter even if its own score is similar to the prior year.
- The measure or its specification changed. A respecified measure or a replacement can make the new result different from the older measure’s result.
- The weight changed. A measure that counts more or less can shift the summary or overall weighted calculation even when its star rating stays constant.
- The measure set or calculation rules changed. Additions, retirements, and applicable adjustments can affect which results enter the calculation and how they are combined.
Guardrails limit some movement in cut points, but they do not make cut points permanent. For that reason, do not interpret a rating change by itself as proof that a plan’s care improved or worsened by the same amount. To understand the change, compare the relevant year’s measure results and weights, and note whether the measures and specifications remained comparable.
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CMS publishes star ratings as one quality signal alongside plan benefits and costs in Medicare Plan Finder. A star rating can help narrow a comparison, but it cannot tell you whether a particular plan’s cost-sharing, benefits, coverage, or provider network fits your needs. Keep the quality score separate from the practical coverage decisions.
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- Confirm the rating year. The 2027 ratings were published October 8, 2026, for contract year 2027. Make sure you are comparing ratings for the same year rather than mixing a current rating with an older one.
- Identify the contract type. Determine whether the plan is MA-only or MA-PD. For an MA-PD option, look at Part C and Part D performance as well as the overall rating; each answers a different part of the quality question.
- Look beyond the overall star count. Review relevant measure categories and individual results where available. A summary number compresses results across measures with different weights.
- Check year-to-year comparability. Consider whether measures were added, retired, respecified, or assigned different weights. Those changes can affect the score independently of a plan’s performance.
- Compare benefits, costs, and network fit separately. Verify the coverage and providers that matter to you in the plan details. A higher star rating is not a substitute for checking whether the plan meets those requirements.
For context, CMS reported that approximately 37% of MA-PD contracts—188 contracts—earned four or more stars for 2027, and approximately 71% of MA-PD enrollees were in contracts with four or more stars. These are figures for the 2027 rating distribution, not forecasts of an individual member’s health outcome or proof that any specific plan is the right choice.
How the rating year, measurement year, and bonus year relate
Several different years appear in descriptions of a star rating. For the 2027 ratings, CMS’s technical notes identify contract year 2027 and state that the ratings use data primarily from measurement year 2025. CMS published the ratings on October 8, 2026, so they are available for 2027 Open Enrollment. The ratings also affect 2028 MA quality bonus payments.
These labels refer to different points in the rating cycle: the measurement period is when the underlying performance data primarily come from; the contract year identifies the rating; publication makes the rating available for plan comparisons; and the bonus-payment effect occurs later. Keeping those dates distinct helps prevent treating 2025 data as if it described a plan’s current-year performance without qualification.
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