Part D

7 Things About Medicare Drug Formularies That You Should Know

A drug formulary is a list of medications covered by a Medicare drug plan. Here are 7 facts about Medicare drug formularies that every beneficiary should know.

A Medicare formulary is the list of prescription drugs that are covered by a particular Medicare Part D or Medicare Advantage plan.

Each plan includes its own formulary that determines which drugs are covered by the plan and how much the drugs cost based on which tier the drug is classified into.

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1. Medicare formularies vary.

The drug formulary of one Medicare plan may differ from another plan’s formulary. Medicare drug formularies can feature both generic and name brand drugs.

2. A Medicare formulary can change throughout the year.

Drugs may be added or removed from the market at any time, and therefore drugs may be added or removed from a plan’s formulary. Drugs may also remain for sale on the market but be removed from a plan’s formulary for a variety of reasons.

Some drugs also may be moved to a different cost-sharing tier (see #3 below) or experience a change in plan restrictions (see #7).

3. A formulary will feature different tiers of drug costs.

Drugs on a Medicare formulary are divided into tiers that determine the cost paid by beneficiaries.

For example, a tier 1 drug might consist of low-cost, generic drugs and require only a small copayment in order to fill a prescription. A tier 4 drug, however, might be a more expensive name brand drug that requires a higher copayment.

The number of drug tiers and the cost breakdown will vary according to each plan.  

A woman smiles as her pharmacist gives her prescription

4. You may be able to get an exception.

Beneficiaries reserve the right to request that a Medicare plan cover a particular drug. You can also request to pay a lower amount for a covered drug.

5. Each formulary must include certain drugs.

All Medicare formularies generally must include coverage for at least two different drugs within most drug categories, and they must include all available drugs for the following categories:

  • HIV/AIDS treatments
  • Antidepressants
  • Antipsychotic medications
  • Anticonvulsive medications to treat seizure disorders
  • Immunosuppressants
  • Anticancer drugs not covered by Medicare Part B

A Medicare formulary won’t include over-the-counter drugs or weight-loss drugs.

6. Members must have access to the drugs on the formulary.

All Medicare plans with prescription drug coverage must make sure that members have access to all medically necessary drugs listed on their formulary.

7. There are restrictions on some drugs on a formulary.

Some drugs on a Medicare formulary come with certain types of restrictions, such as:

  • Prior authorization
    Beneficiaries may be required to show that they meet certain criteria for consuming the particular drug.

  • Step therapy
    Beneficiaries must first try a less-expensive form of a drug that has been proven effective before being covered for the more expensive version.

  • Quantity limits
    There may be a restriction on the dosage amount of a drug or the frequency that the prescription may be filled.

  • Opioid safety limits
    Opioids often contain restrictions for coverage, and doctors will usually work with a beneficiary and a pharmacist to determine a safe level of opioid prescription for each patient.

Find a Medicare plan that offers the prescription drugs you need

You may be able to find Medicare plan options in your area that feature a drug formulary that fits your prescription drug coverage needs.

To compare plans where you live, call to speak with a licensed insurance agent today.

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Or call 1-800-557-6059 (TTY: 711) to speak with a licensed insurance agent. We accept calls 24/7!


About the author

Christian Worstell is a licensed insurance agent and a Senior Staff Writer for He is passionate about helping people navigate the complexities of Medicare and understand their coverage options.

His work has been featured in outlets such as Vox, MSN, and The Washington Post, and he is a frequent contributor to health care and finance blogs.

Christian is a graduate of Shippensburg University with a bachelor’s degree in journalism. He currently lives in Raleigh, NC.

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