Formulary

A formulary is the list of prescription drugs a health insurance plan covers. Every plan has its own formulary, and the formulary determines:

1. Whether a specific drug is covered at all
2. Which “tier” the drug falls into (Tier 1 = cheapest, Tier 4-5 = most expensive)
3. Whether you need prior authorization, step therapy, or a referral to fill it

If your medication is not on the plan’s formulary, you may have to pay the full price out of pocket, request an exception, or switch to a covered alternative.

How formularies are structured

Most plans use a tiered formulary:

• Tier 1: Preferred generics — Lowest copay ($0-$15 typically). Common, low-cost generic drugs.
• Tier 2: Generics / Preferred brand-name — Low copay ($10-$30 typically).
• Tier 3: Non-preferred brand-name — Moderate copay or coinsurance ($30-$80 or 20-30%).
• Tier 4: Specialty drugs — Highest cost share, often coinsurance 20-40%. Cancer drugs, biologics, etc.
• Tier 5 (some plans): Highest-cost specialty.

Generic drugs are almost always the cheapest. Brand-name and specialty are more expensive.

Why formularies matter

Two plans might both “cover prescriptions” but have very different formularies. A drug that costs $30 on one plan might cost $400 on another — or might not be covered at all. This is one of the biggest hidden differences between plans, and it is the most common surprise after enrollment.

Before enrolling: Make a list of every prescription drug you take. Check each plan’s formulary to see:

• Is the drug covered?
• What tier is it on?
• Does it require prior authorization or step therapy?
• Are there formulary alternatives (generic versions)?

A licensed agent can pull this for you for free.

Mail-order vs. retail

Many plans charge lower copays if you fill 90-day supplies through mail order or a network of preferred pharmacies. Maintenance drugs (blood pressure, diabetes, cholesterol) often have substantial mail-order discounts.

Formulary exceptions

If your drug is not on the formulary, you have options:

• Request a formulary exception — Your doctor submits documentation arguing that the drug is medically necessary and alternatives have failed.
• Try a covered alternative — Often a generic version or therapeutic substitute exists.
• Appeal a denial — You have the right to appeal if an exception is denied.
• Switch plans during Open Enrollment if a different plan covers your drug.

How formularies can change

Insurers can change their formularies during the year, but they typically must notify you 60+ days in advance and continue covering your specific drug at the previous tier for at least the rest of the year (the rules vary by state and plan type).

Related terms

• Copay
• Prior Authorization
• Network
• Deductible

Check if your medications are covered — a licensed agent will run your prescription list against the plans in your zip code for free.