how-to
How to Compare Medicare Advantage Drug Formularies
Last Updated: October 30, 2026
Quick Summary
To compare Medicare Advantage drug formularies, list every drug you take with its exact name, strength, and frequency, then look up each plan's formulary using the Medicare Plan Compare tool or carrier lookup tools. Check each drug's tier, cost sharing, restrictions, and pharmacy network, then total your annual costs side by side.
- Most formularies use four to six tiers, moving from lowest cost generics to highest cost specialty drugs.
- Comparing premiums alone misleads you; total annual cost is premiums plus deductible plus your drug costs.
- Coverage on the formulary doesn't guarantee access, since prior authorization, step therapy, and quantity limits may apply.
- Preferred pharmacies often cost less than standard ones, and many plans charge less for 90-day mail-order supplies.
- Formularies change every plan year, so confirm you're reading the upcoming plan year's list before you enroll.
Table of Contents
- Step 1: Build Your Prescription List Before You Compare Medicare Advantage Drug Formularies
- Step 2: Use Medicare Advantage Drug Formulary Lookup Tools
- Step 3: Understand Medicare Drug Tiers Explained
- Step 4: Compare Prescription Costs Between Medicare Plans
- Step 5: Check Prior Authorization, Step Therapy, and Quantity Limits
- Step 6: Verify Pharmacy Networks and Preferred Pharmacies
- Step 7: Confirm Formulary Changes and Midyear Coverage Protections
- Get Independent Help Comparing Medicare Advantage Drug Formularies
- Frequently Asked Questions
Step 1: Build Your Prescription List Before You Compare Medicare Advantage Drug Formularies
Before you compare Medicare Advantage drug formularies, you need one thing on paper: a complete list of every medication you take.
Most people forget at least one drug.
Grab every bottle, inhaler, and tube. Write down:
- The exact drug name, spelled the way it appears on the label
- The strength, such as 10 mg or 50 mcg
- How often you take it, like once daily or as needed
Do this at the kitchen table with all your prescriptions in front of you. Don't rely on memory.
One more tip: include drugs you only take seasonally. A plan that skips your allergy medication is a problem you won't notice until spring.
Step 2: Use Medicare Advantage Drug Formulary Lookup Tools
A drug formulary is a plan's official list of covered medications, sorted into cost levels.
The fastest way to check coverage is the Medicare Plan Compare tool.
Carrier websites also offer formulary lookup tools. These are useful when you've narrowed your choices to a few plans.
A common mistake is checking coverage on a plan's summary page and calling it done.
Step 3: Understand Medicare Drug Tiers Explained
Medicare drug tiers are the cost levels a plan uses to group medications. The tier a drug lands on drives your copayment or coinsurance.
Here's the typical structure:
| Tier | What's Usually On It | Your Cost |
|---|---|---|
| 1 | Preferred generics | Lowest copay |
| 2 | Other generics | Low copay |
| 3 | Preferred brand-name drugs | Moderate copay |
| 4 | Non-preferred brand-name drugs | Higher copay |
| 5 | Specialty drugs | Highest, often coinsurance |
Tier placement is where plans differ most. The same generic drug might sit on Tier 1 with one plan and Tier 2 with another.
For a deeper walkthrough of how formularies are built and why drugs land where they do, read our guide on understanding Medicare Advantage plan formularies.
Step 4: Compare Prescription Costs Between Medicare Plans
Comparing premiums alone will mislead you. A plan with a low monthly premium can carry a higher annual deductible and steeper copayments, and you only see the damage at the pharmacy counter. The fix is to stop comparing plans in the abstract and run the same drug list through each plan's cost structure side by side.
When you compare prescription costs between Medicare plans, look at the full picture:
- Monthly premium: what you pay whether or not you fill a prescription
- Annual deductible: what you pay before the plan starts sharing costs (standalone Part D deductibles are capped annually by Medicare; Medicare Advantage drug plans may set their own deductible up to that cap)
- Copayment or coinsurance: your share at the pharmacy, which depends on the drug's tier and whether your pharmacy is preferred
That last number is the one that matters. A plan that looks cheap monthly can cost more by December.
Build a side-by-side worksheet
A repeatable workflow beats eyeballing brochures. Set up one row per medication and one column per plan you're considering, then fill in the same cells for every plan:
- Drug and dose (from your Step 1 list)
- Tier placement in that plan
- Cost sharing at your preferred pharmacy for a 30-day fill
- Restrictions (prior authorization, step therapy, quantity limit, see Step 5)
- Mail-order cost for a 90-day fill, if you use maintenance drugs
- Whether the deductible applies to that tier
Then total each plan's column: 12 months of premiums, plus the deductible you expect to satisfy, plus your per-fill cost sharing multiplied by fills per year. Run the math for a typical year and for a heavy year (a new prescription, a specialist visit, a temporary fill at a non-preferred pharmacy). The plan that wins on the typical year may lose badly on the heavy year.
A worked example
Suppose you take three maintenance drugs: a Tier 1 generic, a Tier 2 generic, and a Tier 3 brand-name drug. Plan A has a lower premium but places the brand drug on Tier 4 with 30% coinsurance; Plan B has a higher premium but keeps that drug on Tier 3 with a flat copay. On paper Plan A looks cheaper. Once you multiply the coinsurance by the drug's retail price for 12 fills, Plan B often closes the gap or pulls ahead, and the gap widens if you also need a fourth drug midyear.
The Medicare Plan Compare tool can help you estimate yearly drug costs. Run it with your full medication list, then compare two or three plans side by side using the worksheet above so you can see where the estimates come from. For the broader framework on weighing plans overall, see our step-by-step guide to comparing Medicare Advantage plans.
Step 5: Check Prior Authorization, Step Therapy, and Quantity Limits
Coverage on the formulary doesn't guarantee easy access. Many plans attach coverage rules to specific drugs, and these rules trip people up after enrollment.
The three you'll meet most:
- Prior authorization: the plan must approve the drug before it's covered
- Step therapy: the plan requires you to try a cheaper drug first
- Quantity limits: the plan caps how much you can fill in a set period
A drug with prior authorization isn't denied. It just needs paperwork, and your doctor has to send it. That delay is real, and it's worth knowing before you pick.
If a plan you're considering uses prior authorization, read our walkthrough on how Medicare Advantage prior authorization works. And if you've been burned by a stalled approval before, our tips on avoiding prior authorization problems can save you a headache.
Step 6: Verify Pharmacy Networks and Preferred Pharmacies
Your pharmacy choice changes your drug cost, even within the same plan.
Check two things for each plan:
- Is your current pharmacy in the plan's network?
- Is it a preferred pharmacy, or a standard one?
A plan can cover your drug and still cost more because your pharmacy isn't preferred. If you use a chain, confirm the specific location, not just the brand.
Also check mail-order options. Many plans charge less for a 90-day mail-order supply. If you take several maintenance drugs, that difference is worth a look.
Step 7: Confirm Formulary Changes and Midyear Coverage Protections
Formularies change every plan year. A drug covered this year might move tiers, gain a restriction, or drop off next year. Before you enroll, confirm the formulary you're reading is for the upcoming plan year, not the current one, plan websites and the Medicare Plan Compare tool label the plan year, and the annual enrollment window is when next year's formularies go live.
What happens if your drug changes midyear
Once you're enrolled, Medicare rules limit how much a plan can change your drug coverage during the year. The protections you should know:
- Negative changes generally require advance notice. If a plan removes a drug from its formulary, moves it to a more expensive tier, or adds a prior authorization, step therapy, or quantity limit, the plan generally must tell you in writing before the change takes effect. Keep every notice, a formulary change letter looks like junk mail until it isn't.
- Transition fills. If you're already taking a drug that the plan is removing or restricting, you can generally get a temporary supply so you and your doctor have time to switch or request an exception (Drug plan rules). The length of the transition period and the number of fills vary by plan, so ask the plan's member services line for the specific transition policy in writing.
- Exceptions and appeals. If a drug isn't covered or a restriction blocks you, you can ask your doctor to request a formulary exception (asking the plan to cover a drug not on its list or to waive a restriction). If the plan denies it, you have the right to appeal, and the denial notice must explain the deadline and how to file. Ask for the plan's coverage determination and appeals process in writing.
What to do when a medication isn't covered at all
- Check the formulary for a covered alternative on the same tier, often a different drug in the same class works as well and costs less.
- Ask your doctor to request a formulary exception with the clinical reason documented.
- File an appeal if the exception is denied, following the deadline in the denial notice.
- Use the transition fill if you're mid-year and already taking the drug, while you work through steps 1-3.
- Switch plans during a valid enrollment period if the drug is a long-term need the plan won't cover.
Verify before you enroll, not after
Before you commit to a plan, pull the upcoming plan year's formulary and check three things for each drug on your list: Is it on the formulary? What tier? What restrictions? Then confirm the plan's transition and exception policies so you know your options if something changes midyear. If you're comparing plans and one has a restriction on a drug you rely on, that restriction belongs in your Step 4 worksheet next to the cost, it can matter as much as the copay.
Get Independent Help Comparing Medicare Advantage Drug Formularies
This process takes hours, and one missed drug or restriction can cost you real money all year.
Your Medicare Advantage Guy offers a free service with no obligation. Michael Wilson is a licensed, independent advisor who compares plans from multiple top-rated carriers.
You can get plain-English guidance aimed at finding a plan that keeps your doctors in network and fits your budget. When you're ready to stop comparing alone, request your free Medicare Advantage quote and we'll walk through your options together.
Frequently Asked Questions
How do I check whether my prescriptions are covered by a Medicare Advantage plan?
Start by writing down every medication you take, including the exact name, dosage, and how often you fill it. Then use the plan's formulary list or the Medicare Plan Compare tool on Medicare.gov to search each drug. Look for whether the drug appears on the list, which tier it falls into, and whether the plan requires prior authorization, step therapy, or quantity limits. If a drug is missing or restricted, call the plan directly to confirm before you enroll. A local independent agent can also run this check across multiple plans for you at no cost.
What should I compare when reviewing Medicare Advantage drug formularies?
Focus on four things: whether each of your current medications is on the formulary, which tier each drug sits in, what restrictions apply (prior authorization, step therapy, quantity limits), and whether your pharmacy is in the plan's preferred network. Then add up the monthly premium, annual deductible, and copays or coinsurance for a full year of your actual prescriptions. The plan with the lowest premium is not always the lowest total annual cost. A side-by-side comparison using your real drug list shows the difference.
Can a Medicare Advantage plan change its drug formulary midyear?
Yes, but with limits. Plans can generally change formularies at the start of the plan year, and CMS rules allow midyear changes only in specific circumstances, such as when a drug is removed from the market or a new generic becomes available. If your drug is affected midyear, you should receive advance notice and information about alternatives or your right to request an exception. Keep your plan's member materials and call member services if you notice a change at the pharmacy counter. An independent advisor can help you understand your options if a midyear change disrupts your coverage.
What should I do if my medication is not on a plan's formulary?
First, ask your prescriber whether a similar drug on the formulary would work for you. If not, you or your doctor can request a formulary exception from the plan, which asks the plan to cover the drug as if it were on the formulary. You can also ask about the plan's transition policy if you are already taking the drug and switching plans. Compare other Medicare Advantage plans during the enrollment period to see which ones list your medication. An independent agent can check formularies across multiple carriers and help you find a plan that covers what you take.
Comparing drug formularies on your own is doable, but it's easy to miss a restriction or a pharmacy detail that changes your costs. We'd rather you didn't find out at the counter. Get started with Your Medicare Advantage Guy and get a personalized comparison from an independent advisor who works for you, not a carrier.
