How to Choose a Medicare Part D Plan (2026 and 2027)

Nobody can tell you the best Medicare Part D plan, and any page that claims to is selling something. The cheapest plan for a person taking two generics is frequently one of the most expensive plans for a person taking a brand-name blood thinner, because Part D plans compete on which drugs they cover and at what tier, not on a single headline price.

What you can do is run a repeatable comparison. This is the procedure, using the free official tools, with the 2026 numbers you will see on screen this fall and the 2027 numbers CMS has already announced. Open enrollment for plan year 2027 runs October 15 to December 7, 2026.

Step 1: Write Down Your Actual Drugs, Doses and Quantities

Before you open any website, make a list. For each prescription you need the exact drug name (brand or generic), the strength in milligrams, how many you take per day, and the quantity you fill at a time. A 90 day fill and a 30 day fill can price out very differently.

Pull the labels off the bottles rather than working from memory. A misspelled drug or a wrong strength will produce a cost estimate that is wrong by hundreds of dollars, and this is the single most common reason people end up in the wrong plan.

Step 2: Check Extra Help Before You Shop

Do this first, because qualifying changes everything downstream. Extra Help (the Part D low income subsidy) zeroes out your plan premium and deductible and caps what you pay at the counter. Per CMS’s CY 2027 Rate Announcement, the 2026 maximum copays for the main subsidy group are $5.10 for a generic and $12.65 for a brand drug, rising to $5.80 and $14.40 in 2027.

Medicare.gov puts the 2026 eligibility limits at $23,940 in annual income and $18,090 in resources for one person, and $32,460 and $36,100 for a married couple. If you qualify, premium shopping becomes close to irrelevant and you should read Extra Help and Medicare Savings Programs instead of comparison shopping on price.

Step 3: Run Your List Through the Official Medicare Plan Finder

The tool is called Medicare Plan Finder and it lives at medicare.gov/plan-compare. It is free, it takes no personal information beyond a ZIP code if you do not want to log in, and it is the only tool that prices your specific drug list against every plan sold in your county.

Enter your drug list, then enter the pharmacies you actually use. CMS says Plan Finder is updated with the following year’s plan data by October 1, so the 2027 plans should be visible before open enrollment opens on October 15. For 2026 CMS also added filters for supplemental benefits and provider matching.

Step 4: Compare Total Annual Cost, Not the Premium

Plan Finder sorts by estimated total yearly drug and premium cost. That is the number that matters. Premium alone is close to meaningless: KFF found that in 2026 the 78% of stand-alone plan enrollees facing the full $615 deductible paid an average premium of just $22 a month, while the 4% in zero-deductible plans paid an average of $127.

The spread is real in both directions. Every state has at least one $0 premium stand-alone plan, the lowest priced national plan averages just under $6 a month, and 20% of enrollees without Extra Help pay $100 a month or more. CMS projected the 2026 average stand-alone total premium at $34.50, down from $38.31 in 2025; KFF’s enrollment-weighted figure for the same year is $36, down from $39. Either way, a $10 premium difference is trivial next to a drug that sits on tier 4 in one plan and tier 2 in another.

Also read the deductible line. No Part D plan may charge more than $615 in 2026, and CMS has set that ceiling at $700 for 2027. The out-of-pocket cap rises from $2,100 in 2026 to $2,400 in 2027. More detail on those stages is in Part D costs and the donut hole.

Step 5: Confirm Each Drug Is Covered, and at What Tier

Plan Finder will flag drugs a plan does not cover, but check the tier for the ones it does. The tier drives your share of the price, and CMS caps what plans may charge on each one. For CY 2027 the maximum standard retail copays are $20 on the generic tier, $47 on the preferred brand tier and $100 on the non-preferred tier, with maximum coinsurance of 25% on preferred tiers and 50% on non-preferred.

Specialty tier placement is the one that hurts. A drug qualifies for a specialty tier only if its 30 day ingredient cost exceeds a CMS threshold, which rises from $950 in 2026 to $1,080 in 2027. Specialty drugs typically carry 25% to 33% coinsurance rather than a flat copay, and most plans will not grant a tiering exception off a specialty tier. See drug formularies for how tiers and exceptions work.

Step 6: Check the Pharmacy Network and Preferred Pricing

Part D plans set two prices for the same drug: preferred retail cost sharing at pharmacies in their preferred network, and standard retail cost sharing everywhere else in network. The gap is often large enough to swamp the premium difference between two plans.

In Plan Finder, enter every pharmacy you would realistically use, including a mail order option. Then check whether your regular pharmacy is preferred, standard or out of network entirely for each plan on your short list. A plan that is cheapest on paper is not cheapest if your pharmacy is standard and the nearest preferred one is 30 minutes away.

Step 7: Look for Prior Authorization, Step Therapy and Quantity Limits

These are utilization management flags, and they are common. MedPAC’s June 2025 report to Congress, using 2025 Part D formulary files, found that 53% of on-formulary products in stand-alone drug plans carried some form of utilization management: 42% had quantity limits, 27% required prior authorization and 3% required step therapy.

A flag is not a denial, but it is paperwork and delay before your first fill. If two plans price the same for you and one flags your drug for prior authorization, take the one that does not.

Step 8: Read the Star Rating for What It Measures

CMS scores each plan from 1 to 5 stars and publishes summary ratings in half-star steps. Stand-alone drug plans are rated on up to 12 measures covering things like customer service, complaints, appeals handling, member experience and drug safety. They are not rated on whether your drugs are covered cheaply.

The 2026 numbers are sobering. Of 40 rated stand-alone plan contracts, only 2 earned 5 stars, roughly 23% earned 4 or more, and the enrollment-weighted average was 3.01 out of 5. Weighted by enrollment, only about 2% of stand-alone plan members are in a 4-star-or-better contract. Use the rating as a tiebreaker between two plans that cost you the same, not as a reason to pay more. CMS does flag consistently poor performers, marking them on Plan Finder with a low performing icon; four contracts carried that flag for 2026, all of them Medicare Advantage drug plans.

Step 9: Confirm the Window and How to Switch

Medicare Open Enrollment is October 15 to December 7. Medicare.gov states that your new plan must receive the enrollment request by December 7, and coverage starts January 1. You do not need to cancel your old plan; enrolling in a new one disenrolls you automatically. More on the calendar is in when open enrollment happens.

Compare every year even if you are happy. Plans change formularies, tiers and premiums annually, and 2027 carries extra risk: CMS announced on July 28, 2026 that it is ending the voluntary Part D Premium Stabilization Demonstration after 2026, which has been damping stand-alone premium swings since 2025. The 2027 national base beneficiary premium is $41.33, up 6% from $38.99. If you skip Part D without other creditable coverage, you face a permanent late enrollment penalty.

Where the “Best Part D Plan” Search Results Go Wrong

Search that phrase and most of the first page is lead generation. Those pages exist to collect your phone number and route it to a licensed agent who is paid per enrollment, and the agent may only represent the carriers they are contracted with. Nothing about that is illegal, but it is not a comparison of all 360 plans.

The free alternatives are genuinely free. Plan Finder covers every plan sold in your county. 1-800-MEDICARE is staffed 24 hours a day. And the State Health Insurance Assistance Program (SHIP) provides one-on-one, unbiased counseling at no charge: per HHS’s Administration for Community Living there are 54 SHIP grantees covering every state plus DC, Puerto Rico, Guam and the U.S. Virgin Islands, running more than 2,200 local sites with over 12,500 counselors. Find yours through the locator at shiphelp.org or by calling 877-839-2675.

The Bottom Line

Build the drug list, check Extra Help, then let Plan Finder rank plans by total annual cost against your real pharmacies. Verify tier placement, network status and utilization management flags on your top two or three, use the star rating only to break a tie, and enroll by December 7.

CMS will publish the full 2027 landscape in mid-to-late September 2026, so the final 2027 premiums and plan counts land only weeks before enrollment opens. If your out-of-pocket costs still look unmanageable after all of this, look at the Medicare Prescription Payment Plan for smoothing them across the year, and compare your plan’s price against cash options like Cost Plus Drugs and GoodRx for individual generics. For the wider picture of how Part D fits with the rest of your coverage, start at Medicare Part D and the parts of Medicare explained.