A formulary is the list of prescription drugs a plan covers, organized into tiers that set the patient's cost-sharing. A drug that isn't on the formulary generally requires a formulary exception, supported by medical necessity.
Tiers and coverage
- Drugs are grouped into tiers (e.g., generic, preferred brand, non-preferred, specialty) with rising cost-sharing.
- A non-formulary drug typically isn't covered without an exception.
- Formulary placement can change, which affects coverage mid-year.
Formulary exceptions
When a needed drug is non-formulary or on a disfavored tier, a formulary exception request — backed by the prescriber's medical justification — asks the plan to cover it (or at a lower tier). It's the drug-benefit analog of a medical-necessity appeal.
Frequently asked
What if my drug isn't on the formulary?
Why did my drug stop being covered?
Primary sources: Medicare Part D covered drugs & formulary (42 U.S.C. 1395w-102). General information, not legal or medical advice — confirm against the governing rule for the plan type.
When the appeal has to be written, and cited
Upload the denied EOB and Merits returns a complete, citation-verified appeal letter — the clinical argument, the payer's own coverage criteria, and your federal appeal rights — in about a minute.