A formulary is the plan’s list of covered medications, organized into tiers. Lower tiers — generics — cost you least. Higher tiers — brand-name and specialty drugs — cost most. Drugs absent from the formulary are not covered at all, though exceptions can be requested.
What to do before you enroll, not after: look up every medication you take on the plan’s formulary, and note which tier it’s on. Two plans with identical premiums can differ by hundreds of dollars a year on one prescription.
When a drug isn’t covered:
- Ask the prescriber whether a formulary alternative is clinically equivalent. Often one exists.
- Request a formulary exception — plans must have a process, and a prescriber’s supporting statement matters.
- If denied, you have appeal rights, including external review in New York.
- Separately, compare the cash price with a pharmacy discount program. For some generics it beats the insured price, and that’s worth knowing before you argue with anyone.
Formularies change annually. A drug covered in 2026 can move tiers in 2027, which is one of the few real reasons to re-read plan documents during open enrollment.
Also called: drug list, preferred drug list. Reference: Formulary on Wikipedia — general definition, not New York specifics.
More in Glossary of health coverage and billing terms
- Coinsurance — Your percentage share of a bill after the deductible — 20% of a $4,000 procedure is $800.
- Out-of-pocket maximum — The annual ceiling on what you pay for in-network covered care. After it, the plan pays 100%.
- Network (in-network and out-of-network) — The set of doctors and hospitals your plan has contracted with. Outside it, you pay much more.
This page explains how the system works. It is not medical advice. More.