What Is a Formulary?

How it affects what you pay

Where a drug sits on your plan's formulary tiers is one of the biggest factors in your out-of-pocket cost. Lower tiers, usually reserved for generics, carry the smallest copays, while higher tiers for brand-name and specialty drugs carry larger copays or coinsurance percentages (HealthCare.gov Glossary, drug list/formulary). If a medication isn't on the formulary at all, your plan may not cover it, which can mean paying the pharmacy's full cash price unless you pursue an exception or switch to a covered alternative with your doctor. Because formularies can change during the plan year, it's worth checking yours periodically, especially before a refill of an expensive medication.

Example

Consider a hypothetical three-tier formulary: Tier 1 might include common generic drugs with the lowest copay, Tier 2 might include preferred brand-name drugs with a mid-range copay, and Tier 3 might include non-preferred brand-name or specialty drugs with the highest cost-sharing. A person filling a Tier 1 generic would generally pay less out of pocket than someone filling a Tier 3 brand-name drug for a similar condition, though actual amounts depend entirely on the specific plan. This is a general illustration, not real plan pricing.

Why plans use formularies

Health plans and Part D sponsors build formularies to balance covering medically necessary drugs with managing overall costs, often preferring generics and drugs with favorable negotiated rates (HealthCare.gov Glossary, formulary). This is also where tools like prior authorization and step therapy come in, since formularies often specify which drugs require these extra steps before coverage applies. See our full guide on formulary tiers explained for more detail on how tier placement is decided.

If your medication is not covered or is on a high tier

Ask your doctor whether a formulary-preferred alternative exists that treats the same condition, since switching to a covered drug is often the fastest way to lower your cost. You can also ask your insurer about a formulary exception process, which sometimes allows coverage of a non-preferred or non-listed drug when medically justified. While you sort that out, compare prescription prices on BetterBuyRx to see what the cash price looks like at nearby pharmacies as a backup option.

Checking before you fill

Formularies are usually published on your insurer's or Part D plan's website and are also summarized in your plan's Summary of Benefits and Coverage. Search your medication on BetterBuyRx to compare pricing across pharmacies regardless of your plan's tier structure, which can be useful when deciding whether to fill through insurance or pay cash for a specific prescription.