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Check Your Part D Formulary Before Enrolling Checklist

A checklist for confirming your prescriptions are actually covered, and at what cost, before enrolling in a Medicare Part D or Medicare Advantage drug plan.

Medicare3 min readReviewed 2026-09-22

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Short answer

Before enrolling in any Medicare drug plan, checking each of your prescriptions against that specific plan's formulary -- not just the plan's general reputation -- is what actually determines your real out-of-pocket cost.

Use this before you call.

Not sure if your prescriptions are covered? Call GetFastRates.com before you enroll.

List every prescription you currently take, including dosage and frequency.

Check each drug against a specific plan's formulary, not a general summary.

Note which cost tier each drug falls into for that plan.

Check whether any drug requires prior authorization or step therapy.

Compare your preferred pharmacy's network status for that plan.

The same drug can cost very differently across plans

Two Part D or Medicare Advantage drug plans can place the same medication on very different cost tiers -- comparing plans by premium alone can miss a much larger difference in your actual prescription costs.

Formularies can change during the year

A plan's formulary isn't guaranteed to stay the same all year -- checking it again during Annual Enrollment Period, not just when you first enroll, helps catch a change before it surprises you at the pharmacy.

Plans are generally required to give advance notice of formulary changes
A drug moving to a higher tier is one of the most common mid-year cost surprises

Common questions about this topic

Where do I find a plan's specific formulary?

Medicare's plan finder tool lets you enter your specific prescriptions and compare real costs across plans available in your area, rather than relying on a general summary.

What if my drug isn't on any plan's formulary?

You or your doctor can generally request a formulary exception, though it's not guaranteed to be approved -- worth checking before assuming a drug is entirely uncovered.

Tools that can help

Medicare Enrollment Period CalculatorFind your Medicare enrollment window and what it means for your timing.Medicare Part B Late Enrollment Penalty CalculatorEstimate whether a Part B late enrollment penalty could apply to you.Medicare Plan Ending FinderCheck your carrier and ZIP code against current, verified plan-ending records.

Trusted public sources

These links are provided for general public information. They do not replace a personal coverage review.

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