How Drug Formulary Tiers Work & How to Pay Less (2026)

Your insurance plan’s formulary is a list of covered drugs with each drug assigned to a “tier” that determines how much you pay. BillKarma data shows that 41% of patients on specialty drugs pay more than they need to because they don’t know how to request exceptions, use manufacturer assistance, or compare tier placement across plans. Here is exactly how the tier system works and how to use it to your advantage.

1. The 5-tier formulary system explained

Most commercial insurance plans use a five-tier formulary structure. Each tier has a different copay or coinsurance level, and the gap between tiers can be enormous—especially at the specialty tier:

How tiers are set: Your insurer (or pharmacy benefit manager, PBM) negotiates rebates with drug manufacturers. Drugs that generate larger rebates are often placed in lower, preferred tiers. This means tier placement is not always based on clinical equivalence—a drug can be in a lower tier because it is more profitable for the insurer, not because it is more effective for you.

Formularies change annually. Your plan can move drugs between tiers at the start of each plan year. If a drug you take moves from Tier 2 to Tier 4, your costs can increase by $100+ per month with no clinical change in your treatment. Always review your plan’s updated formulary during open enrollment.

2. How to look up your drug’s tier

You have two main tools:

1. Your insurer’s online formulary tool. Log into your health insurance member portal and navigate to the drug/formulary section. Enter your drug name (generic or brand) and your plan will show you the tier, the cost-sharing at that tier, any quantity limits, prior authorization requirements, and step therapy requirements.
2. Medicare Plan Finder (medicare.gov). If you have Medicare Part D, go to medicare.gov/plan-compare and enter your specific medications. The tool will show you every Part D plan available in your area, what tier each plan places your drug on, and your estimated annual cost under each plan. This is the single most powerful tool for Medicare beneficiaries to minimize drug costs.

When checking your formulary, look for these flags next to your drug:

• PA — Prior Authorization required before the insurer will cover the drug
• ST — Step Therapy required (must try a lower-tier drug first)
• QL — Quantity Limit (plan limits how much you can fill per month)

3. How to request a formulary or tier exception

If your drug is on a high tier or not covered at all, you or your doctor can request a formulary exception (to add a non-covered drug) or a tier exception (to cover a drug at a lower tier’s cost-sharing level). Here is how to do it:

1. Identify the basis for the exception. The strongest grounds are: clinical contraindication to the lower-tier alternative, documented adverse reaction or treatment failure with the preferred drug, or evidence that the specific drug is medically necessary for your condition based on peer-reviewed literature.
2. Have your doctor write a letter of medical necessity (LMN). The letter should state your diagnosis, the specific drug requested, why the preferred lower-tier alternative is not appropriate for you, and cite clinical evidence if possible. Be specific about past trial results if you have already tried the lower-tier drug.
3. Submit the exception request. Your doctor’s office can submit directly through your insurer’s provider portal, or you can submit with the LMN attached. Most insurers have a formulary exception form on their website.
4. Wait for the decision. Standard requests: 72 hours. Urgent (expedited) requests: 24 hours. If denied, you have the right to appeal. Get the denial in writing and request a peer-to-peer review between your doctor and the insurer’s medical director.
5. Appeal if denied. File an internal appeal citing the clinical basis. If that fails, request an external independent review. Under federal law, you have the right to an external reviewer at no cost.

4. Step therapy: what it is and how to bypass it

Step therapy (also called “fail first”) requires you to try a lower-cost drug before the insurer will cover your prescribed higher-tier drug. For example, your plan may require trying two generic antidepressants before covering the brand-name drug your psychiatrist prescribed.

When step therapy can be bypassed without going through the steps:

• You already tried the required drug and it failed (clinical failure)
• The required drug is contraindicated for you (e.g., drug interaction, allergy)
• You have been stable on the current drug and switching would cause clinical disruption
• The required drug is not available (shortage or discontinuation)
• You are transitioning between plans and were already on the drug under your prior plan

Many states have step therapy override laws that require insurers to honor step therapy exemptions in specific circumstances. Submit documentation of any prior failure or contraindication to your insurer as part of a step therapy exception request.

5. Medicare Part D formulary rules

Medicare Part D plans must comply with specific CMS formulary standards, but within those standards there is significant variation between plans. Key rules:

The Inflation Reduction Act (IRA) capped annual Medicare Part D out-of-pocket drug costs at $2,000 in 2025, eliminating the old donut hole coverage gap. If you take expensive specialty drugs under Medicare, your annual out-of-pocket cost is now capped regardless of tier placement.

6. Manufacturer copay cards and accumulator programs

Pharmaceutical manufacturers offer copay assistance cards (sometimes called copay cards or patient assistance programs) that cover or reduce your out-of-pocket cost for brand-name drugs. These can reduce your monthly cost from $200+ to $0 at the pharmacy counter. However, many insurers now use accumulator adjustment programs that block manufacturer assistance from counting toward your deductible or out-of-pocket maximum.

How accumulators work against you: Without an accumulator, a manufacturer pays your $300 monthly Tier 3 copay and it counts toward your $4,000 out-of-pocket maximum. With an accumulator, the manufacturer pays your copay but it does NOT count toward your OOP max. When the copay card runs out (usually after 12 months), you still owe the full deductible and OOP max as if you had paid nothing all year.

What you can do:

• Call your insurer before using a manufacturer copay card and ask specifically: “Does your plan use an accumulator adjustment program?”
• If your plan has an accumulator, look for manufacturer patient assistance programs (PAPs) instead, which provide the drug directly rather than through insurance and have no accumulator interaction.
• Several states (including California, Virginia, and others) have passed laws restricting accumulator programs. Check your state’s rules.
• For Medicare patients: manufacturer copay cards generally cannot be used for Part D drugs (anti-kickback statute). Use Medicare’s Extra Help program or manufacturer PAPs instead.

7. GoodRx vs. insurance: when to skip your coverage

For low-tier generic drugs, GoodRx and similar discount programs sometimes offer prices lower than your insurance copay. This sounds counterintuitive, but it happens because discount programs negotiate cash prices that can undercut even Tier 1 copays for common generics.

When to use GoodRx over insurance:

• Your drug is a common generic (metformin, lisinopril, simvastatin, etc.) and GoodRx shows a price below your Tier 1 copay
• You have not yet met your deductible and would pay full price anyway
• You are uninsured

When to use insurance over GoodRx:

• Your drug is Tier 2 or higher and insurance brings your cost lower than GoodRx
• You want the cost to count toward your deductible and out-of-pocket maximum (GoodRx purchases do NOT count toward insurance accumulators)
• You are close to your out-of-pocket maximum and every dollar of drug spend counts

8. Medicare Extra Help for low-income beneficiaries

Medicare Extra Help (also called the Low Income Subsidy, or LIS) is a federal program that dramatically reduces Part D prescription drug costs for Medicare beneficiaries with limited income and assets.

With Extra Help in 2026, eligible beneficiaries pay no more than a few dollars per prescription for covered Part D drugs, regardless of tier. There is no coverage gap and no deductible. Qualification is based on income (generally up to 150% of the federal poverty level) and asset limits.

To apply, contact Social Security (1-800-772-1213) or apply online at ssa.gov. Medicaid recipients are automatically enrolled. If you or a family member on Medicare struggles with drug costs, Extra Help should be the first call you make.

Frequently asked questions

Sources

• Centers for Medicare & Medicaid Services: Medicare Part D Formulary Requirements
• CMS: Inflation Reduction Act — Medicare Drug Price Negotiation and Part D Out-of-Pocket Cap
• Kaiser Family Foundation: Prescription Drug Cost-Sharing in Marketplace Plans (2025)
• Social Security Administration: Medicare Extra Help (Low Income Subsidy)
• AHIP: Drug Formulary Management and Step Therapy Guidelines
• National Academy for State Health Policy: Accumulator Adjustment Program State Laws (2025)