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Is my drug covered? How to check a Part D formulary

A formulary is your plan's list of covered drugs. Here is how to check yours the right way, and what to do when a drug is not on the list.

Updated September 3, 2026 · 3 min read · by Gerino Alejos

A formulary is the plan's list of covered drugs, sorted into tiers, or price levels. To check yours, put your exact medications and doses into the list and see where each one lands. It takes about half an hour, and most people skip it.

How to check a formulary

1. Write down every medication: name, dose, quantity and how often you fill it. Note whether you take the brand or the generic.
2. Go to the Plan Finder at Medicare.gov and enter your ZIP code.
3. Enter each drug exactly as prescribed, including the dose. A different dose can sit on a different tier.
4. Add your pharmacy, and add a mail order option to compare.
5. Sort by the total cost for the year, not by the premium, the monthly bill for the coverage.

You can also read a plan's formulary on its own website, to confirm what the Plan Finder showed you.

What to look for beyond the price

• Tier placement. The same drug can be tier 2 on one plan and tier 4 on another.
• Prior authorization, meaning the plan must approve the drug before it pays.
• Step therapy, meaning you must try a cheaper drug first.
• Quantity limits, capping how much you get on each fill.
• Preferred versus standard pharmacy pricing. One plan can charge different amounts at two pharmacies.

If your drug is not on the formulary

You have real options, and they work more often than people expect. Some drugs are left out by law rather than by the plan. See what Part D never covers.

1. Ask your doctor whether a covered drug would work instead. Often one will, and it costs you far less.
2. Request a formulary exception, a request to cover a drug not on the list. Your doctor sends a statement saying why the covered drugs are not right for you. Plans must answer within set time limits, and urgent requests are faster.
3. If the plan says no, appeal, which means asking for the decision to be looked at again. There are several levels, and a meaningful share of appeals succeed.
4. Switch to a plan that covers the drug during Annual Enrollment, the yearly window when you can change coverage.

Do not pay cash before you try the exception process.

Transition fills

When you join a new plan, or when a formulary changes in January, the plan must give you a temporary supply of a drug you were already taking. That is generally a one month fill inside your first 90 days.

The window is there so you can request an exception, or move to another medication, without going without your drug. Do not find the problem at the pharmacy counter in March.

Formularies change every January

For the new year, a plan can move a drug to a higher tier, add a restriction, or drop it entirely. The Annual Notice of Change (ANOC) lists what your plan is changing, and it arrives in September for this reason.

Check your drug list every fall, even if nothing about your health changed. See reading your ANOC and what to do when a drug is dropped.

Run your list of medications through the Plan Finder now, and check it again each fall. To go over what comes back, call our McAllen office at (956) 687 3334, or enter your ZIP code in the plan pricing box on this page.

Gerino Alejos

Licensed insurance agent · License 3128710 · NPN 18243381

Owner of McAllen Insurance Group, an independent agency on North 10th Street in McAllen. Works with clients across Hidalgo, Cameron and Starr counties on Medicare, Marketplace health, life and auto coverage. Se habla español.