Part D Prescription Drug Plans

What Is Part D?

Medicare Part D provides prescription drug coverage. If you have Original Medicare (Parts A and B), or Medigap, you'll need a standalone Part D plan to get drug coverage. (Medicare Advantage plans usually include Part D automatically.)

Part D plans are offered by private insurance companies and approved by Medicare. Plans vary by which drugs they cover (their formulary), what you pay at the pharmacy, and which pharmacies are in their network.

How Part D Works in 2026

The 2025 Inflation Reduction Act redesigned Part D. Key changes that are now in effect:

• $2,100 annual out-of-pocket cap: The most you'll pay for covered drugs in a year under Part D is $2,100 in 2026 (the cap is indexed each year).
• Medicare Prescription Payment Plan: Allows you to spread your out-of-pocket costs across monthly payments throughout the year.
• Deductible: Maximum $615 in 2026 (some plans have lower or no deductible).

Drug Tiers and Formularies

Each Part D plan has a formulary, a list of covered drugs organized into tiers. Tier 1 (generic drugs) typically costs the least; Tier 5 (specialty medications) costs the most. It's critical to compare plans based on your specific medications.

Extra Help (Low Income Subsidy)

If your income and savings are low enough, you may qualify for Extra Help. It's a federal program that pays part of your Part D premium, deductibles, and copays. In 2026, Extra Help can save eligible beneficiaries thousands of dollars per year in prescription costs.

Weight-Loss Drugs and the Medicare GLP-1 Bridge

Since July 1, 2026 there has been a separate, temporary Medicare program that covers certain GLP-1 weight-loss drugs. It is called the Medicare GLP-1 Bridge, and the thing to understand is that it sits alongside your Part D plan rather than inside it. That distinction decides what you actually pay.

What it covers: Foundayo (tablet), Wegovy (injection or tablet), and Zepbound (KwikPen only, not the single-dose vials or pens).

What it costs: a $50 copay at the pharmacy for a one-month supply.

Who can use it

You need Medicare drug coverage of some kind, a standalone Part D plan, a Medicare Advantage plan with drugs, a Special Needs Plan, an employer group plan or LI NET. You also need to be 18 or older and meet one of these when you start:

• A BMI of 35 or higher
• A BMI of 30 or higher and diastolic heart failure, uncontrolled high blood pressure, or chronic kidney disease at stage 3a or above
• A BMI of 27 or higher and prediabetes, a previous heart attack or stroke, or peripheral artery disease with symptoms

Who cannot

People who already get GLP-1 drugs covered by their Part D plan, and people with type 2 diabetes, moderate-to-severe sleep apnea, or fatty liver disease. If that last group sounds like a strange exclusion, it is because those conditions may already be covered by your Part D plan directly, which is the better route anyway.

How it works

Your doctor sends the prescription to the pharmacy and completes a prior authorization when asked, and has to certify that you are taking the drug as part of a diet-and-exercise program. You get a letter in the mail once it is approved. The approval runs through December 31, 2027 unless you switch to a different GLP-1.

This is a temporary program and the rules are the government's, not mine, so check them at the source: Medicare.gov on weight-loss drugs. If you want help working out whether your plan already covers your GLP-1, call me.

Late Enrollment Penalty

Sign up for Part D when you first can. If you don't, and you have no other drug coverage that counts, you may owe a late enrollment penalty. The penalty is 1% of the national base beneficiary premium for each full month you went without coverage, and it's permanent.