- A Medicare formulary is a specific Part D or Medicare Advantage plan's list of covered drugs; each plan sets its own list and its own tiers, so coverage and cost vary widely between plans.
- The fastest way to check coverage is the free Medicare Plan Finder at Medicare.gov — enter your drugs, doses, and ZIP code to see whether each is covered, on which tier, and at what estimated annual cost.
- Formularies use tiers and utilization controls (prior authorization, step therapy, quantity limits); if your drug is not covered, you can request an exception, appeal a denial, switch to a covered alternative, or change plans during open enrollment.
- For 2026, the Inflation Reduction Act caps Part D out-of-pocket drug spending at $2,100 (verify), covered insulin is capped at $35 per month, and you can spread your out-of-pocket costs across the year through the Medicare Prescription Payment Plan.
- Formularies change yearly and sometimes mid-year, so check yours during open enrollment (Oct 15 – Dec 7) and any time your doctor prescribes something new — and confirm details at Medicare.gov.
Every year, many Medicare beneficiaries discover that a medication they depend on has been dropped, moved to a higher tier, or subjected to new restrictions. Understanding your Medicare formulary is not optional — it is one of the most important steps you can take to avoid surprise costs and coverage gaps. This guide walks you through how formularies work, how to check yours, what to do when your drug is not on the list, and how the 2026 out-of-pocket changes affect what you pay. Figures here can change year to year, so confirm the current numbers at Medicare.gov before you rely on them.
What Is a Medicare Formulary?
A Medicare formulary is a list of prescription drugs covered by a specific Medicare Part D or Medicare Advantage prescription drug plan. Each plan maintains its own formulary, which determines not only whether a drug is covered but also how much you pay out of pocket. According to the Centers for Medicare & Medicaid Services (CMS), Part D plans must cover at least two drugs in most therapeutic categories and substantially all drugs in six protected classes, including cancer, HIV/AIDS, and anti-seizure medications.
Formularies are not static. Plans update them annually, and sometimes mid-year, based on new drug approvals, pricing negotiations, and clinical guidelines. That is why checking your formulary during open enrollment — and whenever your doctor prescribes a new medication — is essential.
How Medicare Formulary Tiers Work
Most Medicare Part D plans organize their formulary into tiers, each carrying a different cost-sharing level. Structures vary by plan, but a typical arrangement looks like this:
- Tier 1 — Preferred generics: Lowest copay, often just a few dollars per prescription
- Tier 2 — Non-preferred generics: Slightly higher copay
- Tier 3 — Preferred brand-name drugs: Moderate copay or coinsurance
- Tier 4 — Non-preferred drugs: Higher coinsurance, often a percentage of the drug’s cost
- Tier 5 — Specialty drugs: Highest cost-sharing, usually a coinsurance percentage of the drug’s price
The exact copay and coinsurance amounts at each tier are set by the plan and change from year to year, so treat any specific dollar figure as illustrative and check your plan’s current documents. The tier your medication falls on directly affects your costs: a brand-name drug on Tier 3 of one plan might sit on Tier 4 of another, creating a significant price difference. For a deeper dive into how formularies are structured, see our article on formulary definition.
How to Check Your Medicare Formulary
Checking your formulary is straightforward, though the process differs depending on whether you are already enrolled or comparing plans.
If You Are Already Enrolled
Log in to your plan’s member portal or call the customer service number on your insurance card. Most plans offer a searchable online drug list. You can also use the Medicare.gov Plan Finder — enter your medications and ZIP code, and it will show whether each drug is covered and on which tier.
If You Are Comparing Plans During Open Enrollment
The Medicare Plan Finder at Medicare.gov is the most efficient tool. Enter every medication you take, including doses and quantities. The tool ranks available plans by total estimated annual cost, factoring in premiums, deductibles, and copays. This comparison can reveal savings of hundreds or even thousands of dollars per year, so it is worth redoing every fall even if you are happy with your current plan.
If You Use CVS Caremark as Your PBM
Many Medicare Part D plans contract with CVS Caremark to manage their pharmacy benefits. If that applies to you, the CVS Caremark member portal provides formulary search tools and cost estimates. You can reach their support team at the CVS Caremark customer service number if you need help navigating the system.
What Happens If Your Drug Is Not on the Formulary
Finding out your medication is not on the formulary is stressful, but you have options. Do not assume you are stuck paying full price.
Request a formulary exception. You and your doctor can ask the plan to cover a non-formulary drug or place it on a lower tier. The request must include a statement from your prescriber explaining why the specific medication is medically necessary and why alternatives on the formulary are not appropriate. Under CMS rules, plans must respond to a standard exception request within 72 hours, and faster for expedited requests when your health could be jeopardized by waiting.
Appeal a denial. If your exception request is denied, you have the right to appeal. The appeals process moves through several levels, starting with the plan and potentially reaching an independent review entity and beyond. Many disputes are resolved at the first or second level.
Consider therapeutic alternatives. Your doctor may be able to prescribe a different drug in the same therapeutic class that is on the formulary. This is often the fastest and simplest path forward.
Switch plans. During Medicare’s annual open enrollment period (October 15 through December 7), you can move to a plan whose formulary covers your medications at a lower cost. The Plan Finder tool at Medicare.gov makes this comparison easy.
Medicare Formulary Restrictions Beyond Tiers
Tier placement is not the only factor that affects access. Many Medicare formularies impose additional utilization-management controls on certain drugs.
Prior authorization. Some medications require your plan’s approval before they will be covered. This typically involves your doctor submitting clinical documentation. Learn more in our guide on what prior authorization means.
Step therapy. Your plan may require you to try a less expensive drug first before it will cover the one your doctor originally prescribed. If the first-line drug fails or causes side effects, your plan will then authorize the preferred medication.
Quantity limits. Plans may cap how much of a drug you can receive per fill or per month. These limits are generally based on FDA-approved dosing guidelines.
2026 Out-of-Pocket Costs: What Changed Under the Inflation Reduction Act
Medicare Part D historically included a coverage gap — the so-called “donut hole” — and, before recent reforms, no ceiling on what beneficiaries could spend out of pocket. The Inflation Reduction Act changed that. Beginning in 2025, Part D introduced a hard annual cap on out-of-pocket drug spending, and for 2026 that cap is $2,100. Once your out-of-pocket spending on covered Part D drugs reaches that amount, you pay nothing more for covered drugs for the rest of the year. (This figure is set by Medicare and adjusts over time, so verify the current number at Medicare.gov.)
According to Medicare.gov, for 2026 no Part D plan may charge a deductible higher than $615, and after any deductible you generally pay 25% coinsurance during the initial coverage phase until you reach the $2,100 out-of-pocket threshold and enter catastrophic coverage. Two other Inflation Reduction Act provisions matter for many beneficiaries:
- $35 insulin cap. Covered insulin products are capped at $35 for a month’s supply, with no deductible applied to insulin.
- Medicare Prescription Payment Plan. You can choose to spread your out-of-pocket drug costs across the calendar year in monthly payments instead of paying large amounts at the pharmacy counter. This does not lower your total cost, but it can smooth out a big bill early in the year. You must opt in, and it is offered through your plan.
Understanding where your medications fall on the Medicare formulary helps you estimate annual costs accurately. Specialty drugs on Tier 5 can push you toward the out-of-pocket cap quickly, while a formulary loaded with Tier 1 generics may keep your annual costs well below it.
How PBMs Influence Your Medicare Formulary
Pharmacy benefit managers (PBMs) play a central role in shaping formularies. Companies like CVS Caremark, Express Scripts, and OptumRx negotiate rebates with drug manufacturers and help decide which drugs make the list. These negotiations happen behind the scenes but directly affect what you pay at the pharmacy counter.
Critics argue that PBM rebate structures can sometimes favor higher-priced drugs over cheaper alternatives, because larger rebates generate more revenue for the PBM. The Kaiser Family Foundation has documented this dynamic extensively. For a broader understanding of how PBMs operate, visit our what is a PBM explainer or our overview of PBM services.
Frequently Asked Questions
How often do Medicare formularies change?
Plans update their formularies at least once per year, typically before the annual enrollment period. Mid-year changes can also occur, but CMS requires plans to provide advance notice to affected members and, in many cases, a transition supply so you are not left without medication while you sort out alternatives.
Can I use a Medicare formulary if I have a Medicare Advantage plan?
Yes. Most Medicare Advantage plans that include prescription drug coverage (MA-PD plans) maintain their own formulary, which functions much like a standalone Part D formulary. Check your plan’s specific drug list for coverage details.
What are the six protected classes in Medicare Part D?
CMS requires Part D plans to cover all or substantially all drugs in six classes: anticonvulsants, antidepressants, antineoplastics (cancer drugs), antipsychotics, antiretrovirals (HIV/AIDS), and immunosuppressants for organ transplant.
Is there a cost to check my Medicare formulary?
No. Checking your formulary is free. You can use the Medicare Plan Finder at Medicare.gov, your plan’s member website, or call customer service at no charge.
What is the Medicare out-of-pocket drug cap for 2026?
For 2026, once your out-of-pocket spending on covered Part D drugs reaches $2,100, you pay nothing more for covered drugs for the rest of the year. Covered insulin is also capped at $35 per month. Confirm the current figures at Medicare.gov, since they are updated periodically.
A Medicare formulary is your specific Part D or Medicare Advantage plan’s list of covered drugs, organized into tiers and sometimes subject to prior authorization, step therapy, or quantity limits. Check yours free on the Medicare Plan Finder at Medicare.gov by entering your drugs and ZIP code; if a drug is not covered, you can request an exception, appeal, switch to a covered alternative, or change plans during open enrollment (Oct 15 – Dec 7). For 2026, Part D out-of-pocket spending is capped at $2,100, covered insulin is $35 per month, and you can spread costs across the year through the Medicare Prescription Payment Plan. This is general education, not insurance advice — verify all figures and your own coverage at Medicare.gov.
Make Your Formulary Work for You
Your Medicare formulary is not just a list — it is a financial roadmap for your prescription drug spending. Check it before every open enrollment period, whenever your doctor prescribes something new, and any time you receive a plan change notice. If your medications are not covered or sit on a high tier, use the exception and appeals processes available to you, and take advantage of the 2026 out-of-pocket cap, the insulin cap, and the option to spread payments across the year. Being proactive about your formulary saves money and prevents disruptions in care. For more on navigating the U.S. healthcare system, explore our healthcare policy guide, and confirm the latest details at Medicare.gov.
Sources
- Medicare.gov — “Costs for Medicare drug coverage” (2026: $2,100 out-of-pocket threshold for catastrophic coverage; maximum plan deductible $615; 25% coinsurance in the initial coverage phase)
- Medicare.gov — Medicare Plan Finder; $35 monthly cap on covered insulin; the Medicare Prescription Payment Plan
- Centers for Medicare & Medicaid Services (CMS) — Part D formulary requirements, the six protected classes, coverage exceptions and the appeals process, and transition/advance-notice rules
- KFF (Kaiser Family Foundation) — analysis of PBM rebate dynamics and formulary decisions