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Medicare Part D is optional prescription drug coverage offered by commercial insurance companies. To be eligible for a Medicare Part D prescription drug plan (PDP), you must have Medicare Part A and/or Part B or certain Medicare Advantage plans without drug coverage. To avoid a late enrollment penalty, you should purchase Part D coverage within nine months of becoming eligible for initial enrollment, or within five months after the month you turn 65 (unless you have a disability or have coverage through your employer).
To determine the best Medicare Part D plans, we carefully considered plan cost to value by weighing premiums, deductibles, copays, maximum out-of-pocket expenses, and drug coverage in the Medicare coverage gap. We also evaluated third-party ratings, including Medicare star ratings, and more.
Best Overall : AARP / UnitedHealthcare
Great value plans, especially if you fill prescriptions at Walgreens
Above-average Medicare star rating
Free mail delivery for 90-day supplies of many drugs
Additional coverage in the Medicare gap
Other plans offer lower deductibles
When compared to other plans, United Healthcare’s AARP PDPs present a great value whether you prefer a low premium or low deductible plan. If you use mostly generics and have access to a Walgreens pharmacy, UnitedHealthcare’s AARP MedicareRx Walgreens plan is a good option as it offers a low premium with $0 copays and no deductible on Tier 1 drugs. And new for 2023, UHC started offering plans with additional coverage in the Medicare donut hole.
The company has relatively strong third-party ratings, with an A+ (Superior) financial strength rating from AM Best, an average CMS star rating of 3.8 for its prescription drug plans, and an average rating of 3.9 out of 5 stars by the NCQA. UnitedHealthcare is also our pick for the best Medicare Advantage plan and best Medicare supplement plan. UHC offers coverage throughout the United States and in Washington, D.C.
Read more in our UnitedHealthcare Medicare Review.
Best for Lowest Premiums : Aetna
Has the lowest national average premium of all PDP providers
Additional drug coverage during the Medicare donut hole
Offers free prescription home delivery
A (Excellent) financial strength rating with AM Best
Lower customer satisfaction ratings than some other insurers
Aetna offers the lowest average premium of all available 2023 PDPs. And more of its plans offer additional drug coverage during the Medicare donut hole than any other major provider. So whether you’re looking for a cheap plan “just in case,” or you need comprehensive drug coverage, you can probably find it with Aetna. Plus, the company is ranked better than average by the NCQA.
Aetna offers three SilverScript plans. You can choose a low premium and higher copays or vice versa. The SmartSaver plan has an average monthly premium of $5.92, but the highest copays. The SilverScript Plus plan has a higher premium, but a $0 deductible and more $0 copays, including during the coverage gap. The SilverScript Choice plan offers a compromise between the two. Coverage is available nationwide.
Learn more in our Aetna Medicare Review.
Highest Medicare Star Rating with Nationwide Availability : Humana
Average CMS rating of 4 out of 5 stars
Low cost plans available with $0 deductible for many generics
No copay and free mail delivery for many generics with select plans
Pharmacy network may limit access in some areas
Out of the companies offering PDP plans nationwide, Humana has the highest average Medicare star rating from the CMS, earning 4 out of 5 stars. This indicates that Humana members have had better experiences with their plan relative to companies with lower-ranked plans. And for 2023, Humana has many more plans with additional drug coverage in the Medicare donut hole, or coverage gap. The company offers three plan types: Humana Basic Rx Plan, Humana Walmart Value Rx Plan, and Humana Premier Rx Plan. Of these, the premier version is the only one to offer additional drug coverage in the Medicare gap. Both the Walmart Value and Premier plans offer $0 deductibles on tier 1 and 2 drugs.
But before you enroll, make sure you have access to pharmacies in Humana’s preferred pharmacy network, which includes Walmart, Publix, Kroger, Sam’s Club, Costco, and Albertsons. Prescriptions outside this network are more costly.
Read more in our Humana Medicare Review.
Great for $0 Copays : Cigna
Low or $0 copays for many generic medications
$0 deductible for many generics medications
Many plans with additional drug coverage in the Medicare gap
Comes with discounts on certain non-covered services
Free prescription home delivery for 90-day supplies of many drugs
Lower NCQA and Medicare star ratings than competitors
Cigna offers three plans to choose from, and though premiums aren’t as low as some competitors, each plan offers low or $0 copays on most generics and a $0 deductible for most generics. Like Aetna’s SilverScript Plus Plan, the Cigna Extra Rx plan also offers additional coverage in the gap and low drug deductibles. Cigna is a good option if you take a lot of generic medications and would rather pay a higher premium with no or low copays and a very low deductible. It's also a good option if you need additional gap coverage. Always check plan costs for your specific drugs as each insurance company’s formulary differs.
Cigna’s plans also come with perks, like discounts on LASIK, Gaiam yoga products, and acupuncture, and most medications are available in a 90-day supply with free home delivery. Cigna PDPs are available in all 50 states.
For more information, read our full Cigna Medicare Review.
Anthem offers the highest-rated Part D prescription drug plans by the CMS, but is only available in 12 states. Very few of its plans offer additional drug coverage in the Medicare donut hole.
The best plan for you will largely depend on the prescriptions you take and which pharmacies are most convenient. But if you take few or no prescription medications and want to avoid the late enrollment penalty, Aetna will likely be the best choice. If you take mostly generics and don’t need additional gap coverage, opt for either UnitedHealthcare or Humana, depending on which pharmacies you prefer. If you need additional coverage during the gap, Aetna and Cigna have plans worth considering.
Frequently Asked Questions
What Is Medicare Part D?
Medicare Part D is a type of insurance that helps you pay for your prescription medications. It’s offered by commercial insurance companies to people who already have Original Medicare or certain Medicare Advantage plans that don’t include drug coverage.
All plans must cover a variety of common prescriptions, and covered drugs are listed in the insurance company’s formulary. Each formulary has tiers that determine how much you’ll pay for different types of prescriptions. For example, generic prescriptions are typically in a lower tier and are less costly than brand-name drugs.
How Much Is Medicare Part D?
The projected average monthly premium for a basic Medicare Part D plan is $31.50 for 2023. But plans are available for much less—Aetna’s SilverScript SmartSaver PDP costs an average $5.92 per month. Your monthly premium isn’t your only cost, though. Most plans have a deductible before your insurance coverage kicks in, and you’ll pay copays and coinsurance costs for prescriptions. These can differ widely depending on the company’s formulary and the specific plan, so it’s crucial to shop around. Typically, plans with higher premiums have lower copays and deductibles, and vice versa.
What Is the Medicare Donut Hole or Coverage Gap?
The Medicare donut hole is a phase of reduced insurance coverage that you enter once you and your plan have spent $4,660 on drug costs in 2023. During the coverage gap, you’re required to cover up to 25% of the cost of generic and brand-name drugs out-of-pocket. Once you’ve spent $7,400 out-of-pocket in 2023, you’ll leave the coverage gap and enter the catastrophic coverage phase, which means you’ll pay a small copay or coinsurance amount for the rest of the year. Some plans offer additional coverage during the gap phase, which can significantly reduce costs.
Big changes are coming for Medicare beneficiaries in the coming years, thanks to the Inflation Reduction Act. Starting in 2024, there will be no coinsurance in the catastrophic phase, and a $2,000 out-of-pocket spending cap will be added for drug coverage in 2025.
What Does Medicare Part D Cover?
Your Medicare Part D prescription drug plan covers medications listed in your insurance company’s formulary, which is a list of covered drugs. Most formularies have four to six tiers, and your copayment will depend on what tier your prescription is in and which phase of Medicare Part D coverage you’re in. Tier 1 drugs are typically generics, which are the lowest cost drugs, while higher tiers include non-preferred brand-name and specialty drugs for a higher cost. Every formulary is a little different. Thanks to the Inflation Reduction Act, insurers also offer savings on insulin that keep your copays at $35.
We identified top companies by market share within the industry offering Medicare prescription drug plans from various business and market insight databases including Statistia, Plunkett, and Gale. We also considered user-generated data from Google to determine public interest and trends in Medicare plans.
Data Collection and Verification
Our data was collected from third-party rating agencies, official government websites and databases, and directly from companies via websites, media contacts, and existing partnerships. Our sources include: AM Best, the National Committee for Quality Assurance (NCQA), J.D. Power, and the Centers for Medicare and Medicaid Services (CMS).
Data was verified to ensure data integrity and accuracy by cross-referencing the records and citation corresponding to each data point with our primary sources.
We calculated star ratings for the quality of each company’s different plan types. Factors considered for companies offering Part D prescription drug plans were:
- Plan quality and customer satisfaction (30%): CMS and NCQA ratings were considered to measure these criteria. Each organization independently rates the quality of Medicare plans on a one-to-five scale to help people compare plans during open enrollment.
- Additional coverage offered in the Medicare gap (25%): The coverage gap or "donut hole" refers to a period when there is a limit on drug coverage. During this time, members are responsible for up to 25% of brand-name and generic drugs. You may spend less on prescription drugs if your plan provides additional coverage during the gap.
- Cost to value (20%): This is a measure of plan value based on plan premiums, deductibles, copays, maximum out-of-pocket amounts, and star ratings.
- State availability (15%): This measure indicates how widely available plans are across the U.S.
- Financial strength (10%): This measure accounts for each company’s AM Best financial strength rating to understand how well it’s positioned to pay insurance claims.