Ratings Methodology for Medicare Part D
Our writers and editors evaluate hundreds of Medicare Part D prescription drug plans to find the best based on cost, quality and customer satisfaction.
5 Companies reviewed 
371 Medicare plans compared 
14,000+ Data points analyzed Data collection and review process
NerdWallet’s editorial team reviewed 5 Medicare Part D companies based on highest enrollment and greatest online search volume.
We review companies covering 86% of all Medicare Part D beneficiaries in the United States.
At the state level, our research covers at least four major Medicare Part D companies in every state.
We collect data points for each Medicare Part D company from its public-facing websites, plan materials, company representatives, public filings and regulator data. These data points are then compared against one another and against NerdWallet’s standards for good health insurance companies to determine a star rating.
Data is collected on a regular basis and reviewed by our editorial team for consistency and accuracy. Final star ratings are presented on a scale of 1 to 5 stars, where a 1-star score represents "poor" and a 5-star score represents "excellent." Ratings are rounded to the nearest tenth of a star.
Note: The federal government calculates its own star ratings for Medicare Part D. These are different from NerdWallet’s star ratings, which consider factors like cost and customer complaints in addition to government quality ratings. NerdWallet’s Medicare Part D star ratings are independently researched, calculated and maintained.
What our star ratings mean
EXCEPTIONAL
Companies with 5 stars are exceptional, with low premiums, competitive out-of-pocket costs, good quality ratings and happy members.
EXCELLENT
Companies in the 4.5 star range are excellent, but might trail leaders' performance on one or two factors.
GOOD
Companies with around 4 stars are strong performers that might not be as well rounded as higher-rated competitors.
LESS COMPETITIVE
Companies with 3.5 stars or fewer could do better in certain criteria, like pricing and customer complaints.
Information updates
Our writers and editors review insurance companies on at least an annual basis and make additional updates throughout the year as necessary. We maintain contact with companies and monitor public data and regulatory filings to keep information current.
Factor evaluation
Cost metrics (50%)
$0-premium plans. We collect premium data for all commercially available Medicare Part D plans from CMS’ Landscape files, which are updated at least annually. Companies are scored based on the proportion of their plans that have $0 premiums.
Average premiums. We compare companies’ average monthly premiums for Medicare Part D plans using Landscape file data. These calculations consider only plans with premiums, since we score the proportion of $0-premium plans separately. Companies with lower monthly premiums earn higher scores.
Average deductible. We compare companies’ average Part D deductibles using Landscape file data. These calculations weight averages by enrollment.
$0-deductible formulary tiers. We collect data about prescription drug coverage from CMS’ Prescription Drug Plan Formulary and Pharmacy Network Information files. Using beneficiary cost data, we calculate the average number of formulary tiers with no prescription drug deductible for each company. Companies with more $0-deductible tiers get better scores.
$0-copay/coinsurance formulary tiers. We also evaluate plans’ formulary tiers with $0 copays for prescription drugs. Companies earn points by offering more $0-copay options.
Average out-of-pocket costs for prescription drugs. We compare estimated out-of-pocket costs for prescription drugs on formulary tiers 1 through 3. To compare both copays and coinsurance, we use reference prices of $15 for Tier 1, $50 for Tier 2, and $200 for Tier 3. Companies with lower out-of-pocket costs get higher scores.
Member experience metrics (25%)
Member experience rating. We compare companies’ performance on the “Member Experience” domain for CMS star ratings. That domain’s measures include members’ ratings of the drug plan and the ease of filling prescriptions. We analyze each company’s average rating across these measures to calculate a member experience score.
Complaint rate. We compare each company’s complaint rates, measured as the number of complaints per 1,000 members from CMS’ Star Ratings measure data. Companies with lower complaint rates get higher scores.
Quality metrics (25%)
Overall CMS rating. The main factor we consider for Medicare Part D plans’ quality is the top-level star rating from CMS. We calculate company-level averages, weighted by enrollment, and give more points to companies with higher scores.
The review team
The writers and editors behind our Medicare Part D reviews are insurance specialists who have had their work featured by or appear in The Associated Press, The Washington Post, USA Today, ABC News, Yahoo Finance, Nasdaq and MarketWatch. Each writer and editor follows NerdWallet’s strict guidelines for editorial integrity.
In addition to Medicare Part D, the team also covers Medicare Advantage, Medicare Supplement Insurance and other subjects related to older adults’ healthcare and finances.
NerdWallet's Medicare team
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