A health insurance formulary is the list of prescription medications that your plan covers. If you take any ongoing medications — or might need prescriptions during the year — the formulary is one of the most important documents to review before choosing a plan. A drug that costs $15/month on one plan's formulary might cost $150/month on another, or might not be covered at all. This guide explains how formularies work, how the tier system affects your costs, and what to do if your medication isn't on the list.
A formulary is essentially a menu of approved drugs. Insurance companies create formularies in consultation with pharmacists and physicians who form a Pharmacy and Therapeutics (P&T) committee. This committee evaluates drugs based on clinical effectiveness, safety, and cost to determine which drugs to include and at what tier.
Formularies exist because there are often multiple drugs that treat the same condition. By steering patients toward clinically equivalent but less expensive options (like generics instead of brand-name drugs), insurers control costs — which in turn helps keep premiums more manageable for everyone in the risk pool.
Under the ACA, all marketplace plans must cover prescription drugs as one of the ten essential health benefits. However, the specific drugs covered and their tier placement vary significantly from plan to plan and carrier to carrier.
Comparing ACA plans in Florida
Most Florida ACA marketplace plans organize their formulary into four tiers, each with different cost-sharing:
| Tier | Drug Type | Typical Cost (Silver/Gold) | Examples |
|---|---|---|---|
| Tier 1 | Generic drugs | $5–$20 copay | Metformin, lisinopril, atorvastatin, omeprazole |
| Tier 2 | Preferred brand-name | $30–$65 copay | Eliquis, Jardiance, Ozempic (varies by plan) |
| Tier 3 | Non-preferred brand-name | $60–$120 copay | Brand drugs not on the preferred list |
| Tier 4 | Specialty drugs | 30–50% coinsurance | Humira, Keytruda, Stelara, specialty biologics |
The tier placement of a specific drug can vary between insurance carriers. A medication that is Tier 2 (preferred brand) on a Florida Blue plan might be Tier 3 (non-preferred) on an Ambetter plan — or not on the formulary at all. This is why comparing formularies is just as important as comparing premiums and deductibles.
Beyond tier placement, formularies often include additional requirements that affect how you access certain drugs:
Step therapy (also called "fail first"): The insurer requires you to try a lower-cost drug before approving a more expensive one. For example, you might need to try metformin (generic, Tier 1) before the insurer approves a GLP-1 medication (Tier 2 or 3). If the first drug doesn't work or causes side effects, your doctor documents the failure and the insurer may then approve the preferred drug.
Quantity limits: Some drugs have caps on how much you can fill per prescription or per month. For example, a migraine medication might be limited to 9 doses per month, or a controlled substance might have a 30-day supply limit per fill.
Prior authorization: Certain drugs — particularly specialty and high-cost medications — require your doctor to obtain advance approval from the insurer before the pharmacy will fill the prescription. This is separate from the standard formulary tier and adds an additional step to the process.
Before enrolling in a plan, check the formulary for every medication you take:
If a medication you take is not on a plan's formulary, you have several options:
The formulary itself — which drugs are listed and at what tier — is generally the same across metal tiers within a single carrier. However, the cost-sharing at each tier varies by metal tier. A Tier 1 generic that costs a $10 copay on a Gold plan might cost $15 on Silver or be subject to the deductible on Bronze. Tier 4 specialty drugs on Bronze plans often require 40–50% coinsurance after a high deductible, which can mean thousands of dollars per fill. On Gold plans, the same drug might have 20–30% coinsurance after a much lower deductible.
For patients with expensive ongoing prescriptions, the metal tier choice can have a larger impact on total annual drug costs than the premium difference between tiers.
A licensed Florida health insurance agent can check formularies across multiple carriers for your specific medications — ensuring you don't end up on a plan that costs you hundreds more per month in drug costs.
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