What Medicare Part D Covers
Medicare Part D prescription drug plans cover a broad range of medications — from affordable generics to specialty drugs and vaccines. Understanding what's covered helps you choose the right plan and avoid unexpected costs.
Understanding Part D Drug Coverage
Every Medicare Part D plan maintains a formulary — a list of covered prescription drugs organized into tiers. The tier a drug is placed on determines how much you pay out-of-pocket. Plans must cover at least two drugs in each therapeutic category, and all plans are required to cover drugs in six "protected classes" — including antidepressants, antipsychotics, anticonvulsants, immunosuppressants, HIV/AIDS drugs, and cancer medications.
Formularies change from year to year. A drug that was covered this year may be moved to a different tier or removed entirely next year. That's why it's essential to review your plan's formulary annually during the Medicare Annual Enrollment Period (October 15 through December 7).
If your medication isn't on your plan's formulary, you have options: you can request a formulary exception from the plan, switch to a covered alternative, or change to a plan that does cover your drug.
Formulary Tiers Explained
Part D plans organize covered drugs into tiers. Lower tiers mean lower costs for you. Here's how the typical five-tier system works.
Preferred Generic
Lowest CostThe lowest-cost tier, featuring widely available generic medications. These drugs have the same active ingredients as their brand-name counterparts but cost significantly less. Most common maintenance medications fall into this tier.
Examples: Metformin, Lisinopril, Amlodipine, Atorvastatin, Omeprazole
Generic
Low CostNon-preferred generic drugs that may cost slightly more than Tier 1 but are still affordable. These generics may be newer to the market or less commonly prescribed alternatives.
Examples: Certain dosage forms, newer generics, combination generics
Preferred Brand
Medium CostBrand-name drugs that the plan has negotiated favorable pricing for. When a generic alternative isn't available or appropriate, preferred brands offer the next best value.
Examples: Eliquis, Jardiance, Entresto, Xarelto
Non-Preferred Brand
Higher CostBrand-name drugs that are not on the plan's preferred list. These cost more because the plan hasn't negotiated special pricing, or because a preferred alternative exists in the same drug class.
Examples: Non-preferred brands where alternatives exist on lower tiers
Specialty
Highest CostHigh-cost medications used to treat complex or rare conditions. Specialty drugs often require special handling, administration, or monitoring. Many are injectable or biologic therapies.
Examples: Humira, Keytruda, Revlimid, certain cancer and autoimmune drugs
Types of Drugs Covered by Part D
Generic Drugs
Generic drugs contain the same active ingredients, dosage, and strength as brand-name drugs but are sold at a fraction of the cost. The FDA requires generics to meet the same quality and safety standards as their brand-name equivalents. Choosing generics when available is one of the best ways to keep your prescription costs low.
Brand-Name Drugs
Brand-name medications are sold under the pharmaceutical company's trademarked name. While they cost more than generics, some conditions may require a specific brand-name drug. Part D plans cover many brand-name medications, though your out-of-pocket cost depends on which formulary tier the drug is placed in.
Specialty Drugs
Specialty medications treat complex, chronic, or rare conditions such as cancer, rheumatoid arthritis, hepatitis C, and multiple sclerosis. These drugs often require special storage, handling, or administration (like injections or infusions). Part D covers many specialty drugs, though they typically have the highest cost-sharing.
Vaccines
Medicare Part D covers a wide range of commercially available vaccines that aren't covered under Part B. This includes the shingles vaccine (Shingrix), the Tdap vaccine, the hepatitis A and B vaccines, and other recommended adult immunizations. Thanks to the Inflation Reduction Act, most Part D vaccines are now available at $0 cost to you.
What Part D Does Not Cover
While Part D provides broad prescription drug coverage, there are some medications and categories that are typically excluded:
- Drugs for weight loss or weight gain
- Drugs for cosmetic purposes or hair growth
- Over-the-counter medications (unless they have a prescription equivalent on the formulary)
- Drugs covered under Medicare Part A or Part B (such as certain chemotherapy drugs administered in a doctor's office)
- Fertility drugs
- Drugs used for the relief of cough or cold symptoms
- Prescription vitamins and minerals (except prenatal vitamins and fluoride preparations)
Note: Some Medicare Advantage plans with drug coverage (MA-PD) may offer additional benefits beyond standard Part D, including limited over-the-counter allowances. Ask us about your options.
Key Things to Know About Part D Coverage
Prior Authorization
Some drugs require prior authorization before the plan will cover them. This means your doctor must confirm the medical necessity of the medication before the plan approves coverage. Your plan's formulary will indicate which drugs require prior authorization.
Step Therapy
Some plans require you to try a less expensive drug before they'll cover a more expensive one. For example, you may need to try a generic first before the plan covers the brand-name version. This is called step therapy or "fail first."
Quantity Limits
Plans may limit the quantity of certain drugs you can get within a given time period. For instance, you might be limited to a 30-day or 90-day supply. Quantity limits help ensure safe and appropriate use of medications.
Formulary Exceptions
If a drug you need isn't on your plan's formulary, or if it's on a higher tier than you think is appropriate, you can request a formulary exception. Your doctor will need to provide supporting documentation explaining why the specific drug is medically necessary for you.
Not Sure If Your Medications Are Covered?
Bring us your medication list and we'll check coverage across multiple Part D plans to find the best fit — at no cost to you.