Choosing a Part D Plan: How to Use the Medicare Plan Finder

Medicare drug coverage, called Part D, is sold through private plans that follow Medicare's rules, and plans can differ a great deal in which drugs they cover, what they charge and which pharmacies they use. Two people can face very different yearly costs depending on their prescriptions and the plan they pick.

Medicare's own comparison tool, the Medicare Plan Finder at Medicare.gov, is built for this job. This guide explains how Part D coverage is offered, what to gather before you search, how to read the results, and what to check before you enroll. It does not recommend any plan or company.

This site is independent and not affiliated with Medicare, CMS or any plan. It offers general information, not insurance, financial or medical advice. Ask your pharmacist or prescriber about your medications, and a SHIP counselor about plan choices.

Two ways to get Part D

Medicare.gov's 2026 drug coverage pages describe two routes:

• A separate Medicare drug plan, which adds Part D to Original Medicare (and to some other plan types). You need Part A or Part B to join one.
• A Medicare Advantage Plan, or other Medicare health plan, that includes drug coverage. You need both Part A and Part B to join.

Medicare.gov (2026) warns that if you're in a Medicare Advantage HMO-POS or PPO plan without drug coverage and join a separate drug plan, you'll be disenrolled from the Medicare Advantage Plan and returned to Original Medicare.

Part D is optional, but Medicare.gov (2026) suggests considering it even if you don't take prescriptions now. Without it, and without other creditable drug coverage (coverage at least as good as Medicare's), the 2027 handbook says you'll likely pay a late enrollment penalty if you join later. Our Costs & Help Paying section explains that penalty.

When you can join or switch

According to the Medicare & You 2027 handbook, you can join when you first become eligible for Medicare, and you can join, switch or drop drug coverage during fall Open Enrollment, which it lists as October 15 to December 7, 2026, for coverage starting January 1, 2027. Certain life events, like moving or losing other coverage, can open a Special Enrollment Period. Our guide to fall Open Enrollment and the Medicare Advantage window covers the timing rules in detail.

What to gather before you search

The Plan Finder can only estimate costs from what you enter, so prepare a complete list:

• Every prescription you take regularly, with the exact name, strength, dose and how often you fill it.
• Your preferred pharmacies, and whether you'd use mail order.
• Your doctors, if you're also comparing Medicare Advantage Plans.
• Any other coverage, such as employer, retiree, TRICARE or VA benefits, and whether it counts as creditable.

The 2027 handbook says you can log into your Medicare.gov account to add your prescriptions and pharmacies, which helps you compare plans. If you have employer or union coverage, the handbook warns you to talk to your benefits administrator before making changes, because joining another plan could cause you to lose that coverage for you and your dependents.

Using the Plan Finder

Medicare.gov's 2026 joining-a-plan page says to add all the prescription drugs you take regularly to get the most accurate monthly and yearly cost estimate for each plan. When you're comparing Medicare Advantage Plans, the 2027 handbook says you can add the providers most important to you, and results will show whether they're in network.

As you compare, focus on the following:

• Estimated total yearly cost. A low premium can be outweighed by higher copayments for the drugs you take. Compare the yearly estimate, not just the monthly premium.
• Whether each of your drugs is on the plan's formulary, the plan's list of covered drugs. Medicare.gov (2026) says each plan has its own formulary, though all must cover most drugs in certain protected classes, such as cancer and HIV/AIDS drugs and antidepressants.
• The tier for each drug. Medicare.gov (2026) explains that drugs in lower tiers generally cost less than drugs in higher tiers, and each plan divides its tiers in its own way.
• Coverage rules. The 2027 handbook describes prior authorization, quantity limits and step therapy, where you may need to try a lower-cost drug first.
• Pharmacy pricing. Medicare.gov (2026) says preferred in-network pharmacies may charge you less, and an out-of-network pharmacy usually costs more.
• Quality ratings. The 2027 handbook says Medicare rates plans from 1 to 5 stars based on quality and performance.

Know the coverage stages and caps

Medicare.gov's 2026 cost page says no drug plan may have a deductible above $615 in 2026 or $700 in 2027, and some plans have none. After any deductible, the same page says you pay 25% coinsurance for covered generic and brand-name drugs until your out-of-pocket spending reaches $2,100 in 2026, or $2,400 in 2027, after which you pay nothing for covered Part D drugs for the rest of the year.

The 2027 handbook also describes the Medicare Prescription Payment Plan, offered by all Part D plans, which spreads your out-of-pocket drug costs across the calendar year. The handbook says it doesn't save money or lower drug costs, and it may not be the best choice for people who get or qualify for Extra Help. If your income and resources are limited, look into Extra Help, covered in our Costs & Help Paying section.

Before and after you enroll

Before you enroll, call the plan to confirm details that matter most to you, such as coverage for a specialty drug. Medicare.gov's 2026 joining-a-plan page lists three ways to join: select Enroll in the Plan Finder, contact the plan directly, or call 1-800-MEDICARE.

After you enroll:

• Expect a transition fill if a drug you already take isn't covered or needs prior authorization. The 2027 handbook says that within your first 90 days you may get a one-time 30-day supply.
• Review your monthly Explanation of Benefits for errors, as the handbook advises.
• If your plan won't cover a drug you need, the handbook says you or your prescriber can ask for an exception.
• Recheck every fall. Plans can change their formularies and costs from year to year, and your plan sends notices of upcoming changes.

Avoid enrollment scams

Medicare.gov's 2026 marketing rules page says plans and agents can't ask for bank or card numbers just to give you a quote, call or text you without permission unless you're already a member, or ask you to pay over the phone or online; the plan must send you a bill. The 2027 handbook advises not sharing your Medicare Number with anyone who contacts you unless you've given them permission in advance; report suspicious calls to 1-800-MEDICARE. For free, unbiased help comparing drug plans, contact your State Health Insurance Assistance Program (SHIP).

Key takeaways

• Part D comes through a separate drug plan with Original Medicare or as part of most Medicare Advantage Plans.
• Enter every prescription, dose and pharmacy into the Medicare Plan Finder and compare estimated yearly costs, not premiums alone.
• Check each drug's formulary status, tier and coverage rules before you enroll.
• Medicare.gov lists out-of-pocket caps for covered Part D drugs of $2,100 in 2026 and $2,400 in 2027.
• Recheck your plan every fall and never give financial details to unexpected callers.

Sources

• Medicare.gov (CMS), Choose how you get drug coverage
• Medicare.gov (CMS), How much does Medicare drug coverage cost?
• Medicare.gov (CMS), How do drug plans work?
• Medicare.gov (CMS), What pharmacies can I use?
• Medicare.gov (CMS), Joining a plan
• Medicare.gov (CMS), Marketing rules for Medicare health & drug plans
• Centers for Medicare & Medicaid Services, Medicare & You 2027 (official handbook)
• Medicare.gov (CMS), Medicare Plan Finder