How Medicare Advantage and Part D star ratings work

Every fall, Medicare rates Medicare Advantage and Part D plans from 1 to 5 stars. The ratings are one of the few apples-to-apples ways to compare plans, but they're easy to misread.

What's measured

For health plans, the ratings look at things like:

• how well members get preventive care and screenings
• how chronic conditions such as diabetes are managed
• member survey results about getting care
• complaints, appeals and customer service

Drug plans are rated on things like customer service, member experience, drug safety and how accurately they price drugs.

Why many plans share the same rating

Ratings are given to the insurer's contract, not to each individual plan. One contract can include dozens of plans in different counties, so they all show the same stars. That's why our plan pages show the contract number next to the rating.

Labels to watch for

• 5 stars. You can switch into a 5-star plan once a year outside the normal enrollment periods, if one is offered where you live.
• Low performer. Plans rated below 3 stars for several years in a row are flagged. Medicare may limit online enrollment in them, and members can switch plans.
• "Plan too new to be measured" or "Not enough data" means there's no rating yet. That's not a bad sign, but it isn't a good one either.

How to use them

Stars tell you about the insurer's track record, not whether a plan fits you. Start by making sure your doctors, hospital and drugs are covered. Then use stars to choose between plans that pass that test.