How to Choose the Best Medicare Part D Plan for Your Medications (2026)

Frequently Asked Questions

How do I choose a Medicare Part D plan?

The best way to choose a Part D plan is to use Medicare's Plan Finder at medicare.gov. Enter every medication you take, your dosage, and your preferred pharmacy. The tool calculates your estimated annual total cost — premiums plus copays — for every plan available in your zip code. The plan with the lowest total annual cost for your specific drugs is generally the best choice.

What is a Medicare Part D formulary?

A formulary is a Part D plan's list of covered drugs, organized into tiers. Tier 1 drugs (usually generics) have the lowest copays. Tier 2 (preferred brand) and Tier 3 (non-preferred brand) cost more. Tier 4 or 5 specialty drugs have the highest cost-sharing. The same drug can be on different tiers — or not covered at all — depending on the plan.

Can I switch Medicare Part D plans every year?

Yes — during Medicare Annual Enrollment Period (October 15–December 7), you can switch to any Part D plan available in your area. Changes take effect January 1. It is critical to review and potentially switch plans every year because formularies, premiums, and copays change annually.

What happens if my Part D plan doesn't cover my medication?

If your drug is not on your plan's formulary, you have three options: request a formulary exception from your plan (your doctor must document medical necessity), ask your doctor for a therapeutically equivalent drug that is covered, or switch to a plan that covers your medication during the next Annual Enrollment Period.

Is a lower Part D premium always better?

No — the premium is only part of the cost. A plan with a $0 premium but high copays for your specific drugs can cost far more than a $40/month premium plan with low copays for those same drugs. Always compare total annual cost — premium plus all expected copays — not just the premium alone.

Choosing the wrong Medicare Part D plan is one of the most expensive mistakes seniors make — and most people never compare plans because they assume all plans are similar. They are not. For the same set of medications, the difference between the best and worst Part D plan in your area can easily be $1,000–$3,000 per year. Here is exactly how to find the best plan for your specific situation.

📌 The Most Important Thing to Know

Part D plans change their formularies (covered drug lists), premiums, and copays every January. A plan that was perfect for you last year may no longer be the best choice. Review and potentially switch plans every October 15–December 7 without exception.

Step 1 — Gather Your Medication List

Before comparing plans, write down every prescription medication you currently take:

Drug name (both brand and generic name if you know it)
Dosage strength (e.g., 20mg, 500mg)
How many tablets per day
Whether you prefer a specific pharmacy (retail, mail-order, or specialty)

This list is the input for every comparison. Missing even one high-cost medication from your list can lead you to the wrong plan.

Step 2 — Use Medicare Plan Finder (The Right Way)

Go to medicare.gov and click "Find health and drug plans."

Enter your zip code
Select "Drug plan (Part D)" if you have Original Medicare
Click "Add drugs" and enter every medication from your list with exact dosage and quantity
Enter your preferred pharmacy
Click "Find plans"

The results show every plan available in your area with an estimated annual drug cost calculated specifically for your medications. Sort by "Lowest drug + premium cost" — this is your total annual cost, which is what actually matters.

Step 3 — Compare the Right Factors

Total Annual Cost — Most Important

This is the sum of your annual premium plus all expected copays for your medications. It is the only number that matters for financial comparison. A plan with a $0 premium and high copays often costs more than a plan with a $35 premium and low copays.

Pharmacy Network

Preferred pharmacies within a plan's network typically have significantly lower copays than non-preferred pharmacies. Confirm your preferred pharmacy — or a convenient alternative — is in-network and preferred. Mail-order pharmacy usually costs less for maintenance medications.

Drug Tier Placement

Check specifically where each of your medications falls on each plan's formulary. A drug that is Tier 1 (low copay) on one plan may be Tier 3 (much higher copay) on another — even though both plans technically "cover" it.

Prior Authorization Requirements

Some plans require prior authorization for certain drugs — meaning your doctor must get approval before the plan covers each fill. Check whether any of your medications require prior authorization on your preferred plan, as this can cause delays and administrative burden.

Step 4 — Watch Out for These Traps

Low premium, high deductible

Some plans have $0 premiums but charge the maximum deductible ($590 in 2026) before covering any drugs except Tier 1 generics. If you take brand-name medications, you pay full cost until the deductible is met each January.

Formulary changes mid-year

Plans can change their formularies mid-year for certain reasons. If your drug is removed mid-year, you are entitled to a 60-day notice and may qualify for a Special Enrollment Period to switch plans.

"Preferred" vs. "standard" pharmacy tiers

Many plans have two pharmacy tiers — preferred and standard. Your copay at a preferred pharmacy can be 30–50% lower than at a standard pharmacy. Always check which tier your pharmacy falls under for each plan.

Step 5 — Get Free Help If You Need It

Every state has a SHIP (State Health Insurance Assistance Program) with free Medicare counselors who can sit with you and compare plans using your medication list. They have no financial interest in which plan you choose — unlike insurance agents who earn commissions. Find your state's SHIP at shiphelp.org or call 1-800-MEDICARE.