Medicare Part D

What Medicare Part D covers

Part D plans are sold by private insurers approved by Medicare. Each plan has a formulary, a list of covered drugs organized into tiers, where lower tiers mean lower cost-sharing. Premiums, deductibles, and copayments vary by plan. Because formularies and costs differ, the right Part D plan depends heavily on which medications you take and at what doses.

• Generic drugs: Lowest-tier drugs with the lowest copayments.
• Preferred brand drugs: Mid-tier brand drugs your plan has negotiated preferred pricing for.
• Non-preferred brand drugs: Brand drugs at standard (higher) cost-sharing.
• Specialty drugs: High-cost medications, typically with a coinsurance percentage rather than a flat copay.
• Vaccines: Most Part D plans cover shingles and other vaccines at no cost.

Who it is for

Anyone on Original Medicare who takes prescription drugs needs a Part D plan. Even if you currently take no medications, enrolling when you are first eligible avoids a late enrollment penalty that raises your premiums permanently. Your licensed insurance agent will match you to the plan with the lowest total cost for your specific drug list.

What Part D is, and the two ways to get it

Medicare Part D helps pay for outpatient prescription drugs, the ones you fill at a pharmacy. Part A covers hospital care and Part B covers doctor visits and some drugs given in a clinic, but neither covers most of what you pick up yourself, and this is one of your Medicare coverage options rather than something that arrives automatically. Private insurers approved by Medicare sell it two ways: a standalone prescription drug plan you add to Original Medicare, alongside a Medigap policy if you have one, or Medicare Advantage plans that include drug coverage, usually called MAPD plans. Each one sets its own formulary and pharmacy network, so two plans in the same county can price the same prescription very differently.

The three stages, and what they cost in 2027

CMS sets limits every plan has to follow, so these apply whichever plan you pick. Coverage moves through three stages in a calendar year, and the third is the one that changed most recently: there is now a hard ceiling on what you can spend. Payments made on your behalf, such as through Extra Help, count toward reaching it. What does not count is your monthly premium, or any drug your plan does not cover at all.

• Deductible: You pay the full cost until you meet it. In 2027 no plan may set one above $700, and plenty set it lower or skip it.
• Initial coverage: You pay a copay or coinsurance and the plan pays the rest, until your out-of-pocket costs reach $2,400.
• Catastrophic coverage: Past that point you pay nothing for covered drugs for the rest of the year.
• Insulin and vaccines: A one-month supply of each covered insulin product costs no more than $35, even before you meet the deductible. Recommended adult vaccines, such as shingles, are covered at no cost.

What you actually pay each month

Your cost is a monthly premium, any deductible, and your share of each prescription. The premium is set by the plan, so it varies widely. The one figure that is national is the base beneficiary premium, $41.33 for 2027, which CMS uses to calculate penalties rather than to price plans. Higher earners also pay an income-related adjustment on top of their plan premium, usually taken from a Social Security check alongside the Part B premium; CMS has not published the 2027 amounts yet. Separately, the Medicare Prescription Payment Plan lets you spread your drug costs into monthly amounts across the year instead of paying at the pharmacy counter. It lowers nothing, but it turns one unaffordable month into twelve manageable ones.

The penalty that catches people who wait

Go 63 days or more in a row without Part D or other creditable drug coverage once your Initial Enrollment Period has ended, and you may owe a late enrollment penalty. It is 1% of the national base beneficiary premium for every full month you went without, and it is added to your premium for as long as you have Medicare drug coverage, not for a year. Twenty months without coverage works out to about $8.30 a month, every month, permanently. Creditable coverage from an employer or the VA protects you, so ask whichever plan you have for the notice that says in writing whether it counts.

Help paying for drugs

Help Paying for Drugs is not a single program. Extra Help, also called the Part D Low Income Subsidy, covers premiums, deductibles and copays for people with limited income and resources, and the 2027 copay amounts have not been published yet. If you already have Medicaid or a Medicare Savings Program you usually qualify automatically, with no separate application. Everyone else applies through Social Security, at no cost.

When you can enroll

When You Can Enroll in Medicare Part D comes down to four windows. Your Initial Enrollment Period, the seven months around the month you turn 65, is the first chance and the one that avoids a penalty. After that the Annual Enrollment Period runs October 15 to December 7 for coverage starting January 1. If you are already in a Medicare Advantage plan, the Medicare Advantage Open Enrollment Period runs January 1 to March 31. A Special Enrollment Period opens after certain events such as moving or losing employer coverage, and it usually lasts a limited time, so it rewards acting quickly.

How to choose a plan for your actual prescriptions

Start with every drug you take and the dose, then check each plan's formulary and the tier it puts each one in, because a plan with a low premium can place your drug on a tier that costs more than the premium saves. Look for prior authorization, step therapy and quantity limits, and remember you can request a formulary exception if something you need is missing. Compare pharmacy networks too, since preferred pharmacies often carry lower copays for the same prescription. Then compare total yearly cost, premium plus deductible plus your share of each drug, not the premium alone, which is where most of the ways to save on Part D actually live. Review it every fall, because formularies change. MAPD plans may also include extra benefits that a standalone plan cannot.

Where to read more

If you are starting from scratch, our plain-English explainer on Medicare Part D goes back to first principles and is the better place to begin than a plan comparison.

Common questions