Medicare Part D plans cover prescription drugs. Medicare beneficiaries with Medicare Part A and/or Part B are eligible to buy a Part D plan to add prescription drug coverage to Original Medicare.

It’s best to sign up for Medicare prescription drug coverage as soon as you’re eligible, though Part D is technically optional. If you don’t buy a Medicare Part D plan or a Medicare Advantage plan with prescription drug coverage, you’re responsible for the full cost of your medications, and there are permanent cost penalties if you sign up late.

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Nerdy Tip
Many Medicare Advantage plans, also called Medicare Part C plans, offer prescription drug coverage, so generally only Original Medicare members need to shop for a separate Part D plan. You can’t combine most types of Medicare Advantage plans with a stand-alone Medicare Part D plan. You can, however, buy a Part D plan if you have a Medicare Supplement Insurance plan that doesn’t cover prescription drugs.


Best Medicare Part D plans for 2023
Unlike Medicare Part A and Part B, Part D plans are sold by private insurance companies, and the plans’ costs, benefits and other features can vary significantly. It’s important to confirm whether a plan covers your prescription drugs, then you’ll want to consider each plan’s strengths and weaknesses.

NerdWallet compares and evaluates Medicare prescription drug plans based on factors including quality ratings from the Centers for Medicare & Medicaid Services, or CMS, prices, cost-sharing requirements, formulary design and more.

Here’s how the top Medicare Part D plans for 2023 stand out:

Best for member satisfaction: AARP/UnitedHealthcare Medicare Part D.

Best for low premiums: Aetna Medicare Part D.

Best for high-coverage, low-cost options: Cigna Medicare Part D.

Best for $0-copay and $0-deductible options: Humana Medicare Part D.

Best for member satisfaction: AARP/UnitedHealthcare Medicare Part D
Average Medicare Part D star rating, weighted by enrollment: 3.21 stars.

Top quality measures that outperformed the national average:

Call center foreign language interpreter and TTY, or teletypewriter, availability.

Medicare plan finder price accuracy.

Few members choosing to leave the plan.

Standout feature: AARP/UnitedHealthcare Medicare Part D plans get few complaints, have few members that choose to leave and outperform several competitors on surveys about members’ experience with the plan.

Company overview: More than 4 million Medicare beneficiaries have AARP/UnitedHealthcare prescription drug plans — the third-highest total among Part D insurance companies.

AARP/UnitedHealthcare Medicare Part D plans are widely available and get solid quality ratings from CMS, especially for measures of member satisfaction. Pricing for the highest-coverage AARP/UnitedHealthcare Part D plan can get expensive, however, and the plans’ ratings for helping members with their medications aren't as strong.

Pros:

You can get an AARP/UnitedHealthcare Part D plan everywhere in the U.S. and in several U.S. territories.

AARP/UHC plans had few complaints and small numbers of members choosing to leave the plans.

You'll pay copays rather than coinsurance for drugs on Tiers 1-3 in most UHC plans.

Cons:

AARP/UHC plans trailed the national average on quality measures related to making sure members are filling their prescriptions and managing their drugs.

Only the most expensive AARP/UHC plan has any $0-copay options.

The AARP MedicareRx Preferred plan has a lot of coverage, but its average monthly premium is higher than that of similar high-coverage options from competitors.

» MORE: Read our review of AARP/UnitedHealthcare Medicare Part D insurance

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Best for low premiums: Aetna Medicare Part D
Average Medicare Part D star rating, weighted by enrollment: 3.5 stars.

Top quality measures that outperformed the national average:

Drug plan quality improvement.

Call center foreign language interpreter and TTY availability.

Few complaints about the drug plan.

Standout feature: Aetna offers the least expensive stand-alone Medicare Part D plan, on average, in 2022.

Company overview: Aetna has more Medicare Part D members than any other company. It’s owned by parent company CVS Health and sells prescription drug plans under the SilverScript brand name.

Aetna's Part D premiums are among the lowest on the market, but you’ll need to look carefully at the copay and coinsurance requirements to see whether you’ll save money overall.

Pros:

Aetna’s SilverScript SmartSaver plan has the lowest average monthly premium of any stand-alone Medicare Part D plan on the market.

The cost is the same whether you choose to get drugs in person or by mail.

Aetna significantly outperformed the national average on CMS’ measure of year-over-year quality improvement.

Cons:

The SilverScript SmartSaver plan has low premiums, but it has higher copays and coinsurance than some competing plans.

Aetna underperformed on quality measures related to helping members get and properly take their medications.

The SilverScript Choice plan used to have no deductible for Tier 1 and Tier 2 drugs, but now the deductible applies to all covered drugs.

» MORE: Read our review of Aetna Medicare Part D insurance

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Best for high-coverage, low-cost options: Cigna Medicare Part D
Average Medicare Part D star rating, weighted by enrollment: 3.52 stars.

Top quality measures that outperformed the national average:

Medicare plan finder price accuracy.

Drug plan quality improvement.

Members’ rating of the drug plan.

Standout feature: Cigna’s high-coverage Part D plan is the cheapest among similar options from market leaders.

Company overview: Cigna is the fifth-largest company offering Medicare Part D plans. It offers some of the lowest prices for high-coverage Medicare Part D plans.

Among the five largest Medicare Part D companies, Cigna has the highest average summary star rating, weighted by enrollment.

Pros:

The Cigna Extra Rx plan is less expensive, on average, than similar high-coverage options from major competitors.

Each of Cigna’s plans has no deductible for drugs on certain formulary tiers (specific tiers vary by plan).

Cons:

Cigna trailed the national average on quality measures related to helping members with conditions like diabetes, high cholesterol and hypertension get and take their medications.

You’ll pay more to get some drugs in person — the lowest copays can require 90-day supplies by mail.