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

Every plan covers a different list at different prices. Here is how to check yours properly, and what to do when a drug is not on it.

Updated August 17, 2026 · 3 min read

A formulary is the plan's list of covered drugs, sorted into tiers. Checking yours is the single most valuable half hour you will spend on Medicare, and most people skip it.

How to check

1. Write down every medication: name, dosage, 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.
3. Enter each drug exactly as prescribed, including 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 total estimated annual cost rather than by premium.

You can also check a specific plan's formulary directly on its website, which is worth doing to confirm what the Plan Finder shows.

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 before covering it.
• Step therapy, meaning you must try a cheaper drug first.
• Quantity limits, capping how much you get per fill.
• Preferred versus standard pharmacy pricing.

If your drug is not on the formulary

You have real options and they work more often than people expect.

1. Ask your doctor whether a covered alternative would work. Often one will, at a fraction of the cost.
2. Request a formulary exception. Your doctor submits a statement explaining why the covered alternatives are not appropriate. Plans must respond within set timeframes, and expedited requests are faster.
3. If denied, appeal. There are multiple levels and a meaningful share of appeals succeed.
4. Change plans during Annual Enrollment to one that covers it.

Do not simply pay cash without trying the exception process first.

Transition fills

When you join a new plan or a formulary changes in January, plans must provide a temporary supply of a drug you were already taking, generally a one month fill in the first 90 days.

That window exists so you can sort out an exception or switch medications without going without. Use it rather than discovering the problem at the counter in March.

Formularies change every January

A plan can move a drug to a higher tier, add a restriction, or drop it entirely for the new year. The Annual Notice of Change lists it, and it arrives in September for exactly 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.