Formulary Tiers Explained: How Drug Tiers Affect Your Prescription Costs (2026)

Insurance formulary tiers are the system insurers use to categorize covered drugs by cost. Understanding tiers helps you predict out-of-pocket costs, identify cheaper alternatives, and make informed decisions during open enrollment. Most plans use 4 to 6 tiers, with each tier having a different copay or coinsurance amount.

Key Facts

Tier 1: Preferred generics, lowest cost ($0 to $15 copay typically)

Tier 2: Non-preferred generics or preferred brands ($15 to $40 copay)

Tier 3: Preferred brand-name drugs ($40 to $75 copay)

Tier 4: Non-preferred brand-name drugs ($75 to $150 copay or 25% to 40% coinsurance)

Tier 5/6: Specialty drugs (25% to 33% coinsurance, often $200+ per fill)

Moving to a lower-tier alternative can save hundreds or thousands per year

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Coverage varies by plan. Use our formulary checker tool to look up your exact copay and restrictions.

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Sources and standards behind this page

Drug coverage in the United States is governed by published rules rather than by any one insurer's summary, and the sources below are the primary ones. They are linked so a reader can check a claim without taking this page's word for it.

FDA Orange Book publishes the therapeutic-equivalence ratings that decide whether a generic may be substituted for a brand-name drug.
FDA generic drug facts sets out what "generic equivalent" means and what a manufacturer must prove.
CMS prescription drug coverage defines the rules a Medicare drug plan formulary must follow and how it may change mid-year.
Medicare.gov drug coverage (Part D) states what a Part D plan is required to offer a member.
CMS prescription drug appeals documents the coverage-determination and exception process when a drug is denied.

This page describes how coverage and formularies work. It is not medical advice, and a reader's own plan documents and prescriber decide what applies to them.

Frequently Asked Questions

Can my doctor move my drug to a lower tier?

Your doctor cannot change the tier, but they can prescribe a therapeutic alternative that is on a lower tier. For example, switching from a Tier 3 brand to a Tier 1 generic in the same drug class. Your doctor can also submit a formulary exception request, asking the insurer to cover your drug at a lower tier if there is a clinical reason.

Why do different plans have different tiers for the same drug?

Each insurer negotiates separate rebate contracts with drug manufacturers. A drug might be on Tier 2 with one insurer (who got a bigger rebate) and Tier 4 with another. This is why comparing formularies during open enrollment is important for finding the best plan for your specific medications.

Do tiers change during the year?

Yes, insurers can change tier placements during the plan year, though they must provide advance notice (typically 30 to 60 days). Mid-year changes often happen when new generics or biosimilars become available. If your drug moves to a higher tier, you can request a formulary exception or switch to a preferred alternative.

Related Resources

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