What Medicare Part D Does

Medicare Part D is the prescription drug coverage piece of Medicare. It pays toward the cost of medications you take at home — pills, inhalers, injections you give yourself. It does not cover drugs you receive in a hospital or doctor's office during a visit; those fall under Part B. Part D is run by private insurance companies that Medicare contracts with, not by Medicare directly.

You choose which Part D plan to join during your enrollment period. The plan you pick determines which drugs it covers, what you pay at the pharmacy, and which pharmacies you can use. Plans change their drug lists and prices every year, so the plan that worked last year may not be your best choice this year.

Key Takeaways

  • Part D is optional, but you pay a penalty if you go without it and later join — the longer you wait, the higher your penalty.
  • You pick a specific plan during open enrollment (October 15 to December 7 each year), and your choice takes effect January 1.
  • Each plan has a formulary — a list of drugs it covers — and you need to check whether your medications are on it before you join.
  • You move through four payment stages as you spend more: a deductible, then shared costs, then a coverage gap, then catastrophic coverage.
  • The plan you choose affects both your monthly premium and what you pay when you pick up a prescription.

The Four Payment Stages in a Part D Plan

Every Part D plan divides the year into four spending stages. Understanding where you are in the year helps you predict what you will owe.

Stage 1: Deductible. You pay the full cost of your drugs until you reach your plan's deductible. Most plans have a deductible between $0 and $550, though this amount changes yearly. Some plans have no deductible at all. Once your out-of-pocket spending hits the deductible, you move to Stage 2.

Stage 2: Initial Coverage. After you meet the deductible, the plan starts to pay its share. You typically pay a copay (a flat amount like $5 or $10) or coinsurance (a percentage like 20 percent). The plan pays the rest. You stay in this stage until your total drug costs — what you paid plus what the plan paid — reach a certain amount. That amount changes yearly but is usually around $5,000.

Stage 3: Coverage Gap (the "Donut Hole"). Once your total drug costs hit the threshold, you enter the coverage gap. Here, you pay a larger share of the cost. For brand-name drugs, you pay 25 percent. For generic drugs, you pay 25 percent as well. The plan does not pay during this stage. You stay here until your out-of-pocket spending reaches a second threshold, usually around $8,000.

Stage 4: Catastrophic Coverage. Once you have spent enough out of pocket to reach the catastrophic threshold, the plan takes over almost all costs. You pay only a small copay or coinsurance, and the plan covers the rest. This stage lasts through the end of the year.

How to Choose a Part D Plan

Part D plans differ in three main ways: monthly premium, which drugs they cover, and what you pay at the pharmacy. You cannot pick the best plan without knowing which medications you take.

Start by listing every prescription drug you currently take, including the strength and quantity. Then go to Medicare.gov and use the Plan Finder tool. Enter your drugs and it will show you which plans cover them and what you will pay in each plan. The tool estimates your total yearly cost — premium plus out-of-pocket costs — so you can compare plans directly.

Pay close attention to the formulary, which is the plan's list of covered drugs. Some plans cover a drug with no restrictions. Others require you to try a cheaper drug first, or to get approval from the plan before they will pay. A few plans do not cover a drug at all. If your current medication is not on the formulary, you have two choices: pick a different plan that does cover it, or ask the plan for an exception (though this takes time and is not always granted).

Also check which pharmacies are in the plan's network. Most plans work at major chains like CVS, Walgreens, and Walmart, but some have smaller networks. If you use a specialty pharmacy for an expensive drug, confirm it is in the plan before you join.

When You Can Join or Switch Plans

You have a limited window each year to join or change your Part D plan. The main enrollment period runs from October 15 to December 7. Any plan you choose during this window takes effect on January 1. If you miss this window, you cannot change plans until the next October, unless you have a may have access to life event.

A may have access to life event includes losing other drug coverage, moving to a new state, getting married or divorced, or having a major change in income. If one of these happens, you have 60 days to join or switch plans. You will need to prove the event occurred — for example, a letter from your former employer saying your coverage ended.

If you are new to Medicare, you have 63 days from the date your Medicare coverage starts to join a Part D plan without penalty. After that window closes, you pay a penalty if you go without coverage.

What Happens If You Do Not Have Part D

Part D is optional, but there is a financial consequence to skipping it. If you go without Part D coverage for more than 63 days in a row after you first become may be able to access for Medicare, you owe a late enrollment penalty for as long as you have Medicare.

The penalty is calculated as 1 percent of the national average Part D premium for each month you were without coverage. The national average premium changes yearly. If you go without coverage for one year, your penalty is roughly 12 percent of that year's average premium, added to your monthly premium forever. If you go without for five years, your penalty is roughly 60 percent of the average premium.

The penalty does not go away if you later join a plan. It stays on your record and increases your premium every month. The only way to avoid it is to have other creditable drug coverage — coverage that is at least as good as Part D — during the time you are not enrolled in Part D.

How to Use Your Part D Plan at the Pharmacy

When you pick up a prescription, you give the pharmacy your Part D member ID card. The pharmacy checks your plan's formulary and your current spending stage, then tells you what you owe. You pay that amount and the plan pays its share directly to the pharmacy.

Keep track of what you spend out of pocket throughout the year. Your plan sends you a statement showing your spending in each stage. Once you reach the coverage gap or catastrophic stage, your costs change, so knowing where you are helps you budget. Some plans offer tools on their website or app to track your spending in real time.

If your pharmacy does not have a drug in stock, ask them to order it or to tell you which nearby pharmacies do. You can also use mail-order pharmacy through your plan, which is often cheaper for drugs you take regularly. Mail-order usually takes 7 to 10 days, so plan ahead for refills.

Frequently Asked Questions

What if my doctor prescribes a drug that my Part D plan does not cover?

You have three options. First, ask your doctor if there is a similar drug on your plan's formulary that would work for you. Second, ask your plan for an exception — you submit a form and the plan reviews whether it will cover the drug anyway. This takes one to three weeks. Third, you can pay out of pocket for the uncovered drug, though this is usually expensive. Your plan must tell you how to request an exception.

Can I change my Part D plan in the middle of the year?

No, unless you have a may have access to life event like losing other coverage, moving, or a major income change. Otherwise you are locked into your plan until the next October 15. If you realize your plan is not working for you, document the reason and contact your plan about whether you may have access to for a change.

Do I have to use a mail-order pharmacy, or can I always go to my local pharmacy?

You can use your local pharmacy if it is in your plan's network. Mail-order is optional. However, some plans offer a lower copay for mail-order, especially for drugs you take long-term. Compare the cost at your local pharmacy versus mail-order before you decide.

What if I cannot afford my copays even with Part D?

If your income is low, you may may have access to for Extra Help, a federal program that pays your Part D premiums and reduces your copays. You can check whether you may have access to through Medicare.gov or by calling 1-800-MEDICARE. Some drug manufacturers also offer copay information cards that reduce what you pay at the pharmacy.

Does Part D cover over-the-counter drugs?

No. Part D covers only prescription drugs. Over-the-counter medications are not covered, even if a doctor recommends them. However, some plans offer a small allowance you can use toward over-the-counter items through a partner program — check your plan's details.