Medicare Part D · Prescription Drug Coverage
Plain English. Five calm steps. No pressure.
Part D helps pay for the prescriptions you fill at the pharmacy. Unlike Parts A and B, it comes from private insurance companies approved by Medicare — so you choose a plan that fits your drugs, your pharmacy and your budget.
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Your Part D Path
Read them in order, or jump straight to what you need.
How drug lists, tiers and pharmacies work.
2027 deductible, coinsurance and the $2,400 cap.
Your first window, Open Enrollment, and special cases.
A simple checklist for finding the plan that fits your drugs.
Enroll yourself, and avoid the late penalty.
Step 1 What It Covers
Part D = Prescription Drug Coverage
Every Part D plan must cover a wide range of drugs, but each plan picks its own list, prices and pharmacies. That's why the right plan for your neighbor may not be the right plan for you.
Each plan has its own list of covered drugs. If a drug isn't on the list, the plan generally won't pay for it — so always check yours.
Drugs are sorted into price levels called tiers. Generics are usually on the lowest tiers; specialty drugs on the highest.
Plans have network pharmacies, and many have "preferred" ones with lower prices. Mail-order can save money on drugs you take every day.
Covered insulin costs no more than $35 a month, and most recommended adult vaccines — like shingles — cost $0.
Insulin ≤ $35/monthTwo ways to get Part D:
Adds drug coverage to Original Medicare. Often paired with a Medigap policy.
Many Medicare Advantage plans include Part D, so your medical and drug coverage come in one plan.
Watch for restrictions: some drugs need your plan's approval first (prior authorization), have quantity limits, or require you to try a lower-cost drug first (step therapy). Look for these notes next to your drugs when you compare.
Step 2 What It Costs
Your 2027 Part D Costs
Monthly premiums vary from plan to plan — some are $0. The rules below set the most any standard plan can charge you in 2027.
| Stage | You pay |
|---|---|
| 1 · Deductible | Full cost, up to $700 |
| 2 · Initial coverage | About 25% |
| 3 · Catastrophic (after $2,400 out of pocket) | $0 |
| Always | |
| Covered insulin (deductible doesn't apply) | $35/month max |
| Recommended adult vaccines | $0 |
2026 figures were a $615 maximum deductible and a $2,100 cap. Source: Centers for Medicare & Medicaid Services.
Already have Part D? Check your mail. A federal program that held down drug plan premiums in 2026 isn't being continued, so many premiums may change for 2027. Your plan's Annual Notice of Change shows exactly what's changing. How to read your ANOC →
If your income is above a certain level, Medicare adds an amount (IRMAA) to your Part D premium. You pay it to Medicare, not your plan. These are the 2026 amounts, based on 2024 tax returns; 2027 amounts are usually announced in November.
| Filed individually | Filed jointly | Added to premium |
|---|---|---|
| $109,000 or less | $218,000 or less | $0 |
| $109,001 – $137,000 | $218,001 – $274,000 | $14.50 |
| $137,001 – $171,000 | $274,001 – $342,000 | $37.40 |
| $171,001 – $205,000 | $342,001 – $410,000 | $60.20 |
| $205,001 – $499,999 | $410,001 – $749,999 | $83.30 |
| $500,000 or more | $750,000 or more | $91.00 |
Married and filing separately? Different brackets apply. Source: CMS and the Social Security Administration.
If your income and resources are limited, this federal program can lower your premium, deductible and copays. Apply through Social Security at ssa.gov/extrahelp or 1-800-772-1213.
Instead of paying big drug costs all at once at the pharmacy, you can spread them into monthly payments through the year. Ask your plan to sign you up — it's free.
Step 3 When to Enroll
Your Enrollment Windows
You first become eligible during the same 7-month window as Parts A and B. After that, most changes happen once a year during Open Enrollment.
Every year from October 15 to December 7, anyone with Medicare can join, switch or drop a Part D plan. Changes start January 1.
Happening nowJoin a drug plan during your 7-month Initial Enrollment Period — even if you take few or no drugs today. A low-premium plan protects you from the penalty.
Around your 65th birthdayIf it's "creditable" — at least as good as Medicare's — you can wait without a penalty. Your employer or union sends a notice each year saying whether it is. Keep it.
Keep your noticeMoving, losing other drug coverage, entering a nursing home, or qualifying for Extra Help can open a Special Enrollment Period outside the usual dates.
Special Enrollment PeriodIn a Medicare Advantage plan? From January 1 to March 31, you can also switch to a different Medicare Advantage plan, or go back to Original Medicare and join a stand-alone drug plan — one time.
Step 4 Compare Plans
The Lowest Premium Isn't Always the Lowest Cost
The plan that's cheapest for you is the one with the lowest total yearly cost for your drugs — premium plus what you pay at the pharmacy. A few minutes of preparation makes comparing easy.
Have these ready before you compare:
Then check each plan for:
Every drug on the plan's list, at a tier you can afford, with any restrictions noted.
Ideally a "preferred" pharmacy, where prices are lowest.
Premiums plus estimated drug costs for the whole year — not just the monthly premium.
A safe practice run · You enroll in nothing there
Step 5 Enroll & Stay Covered
When You're Ready — And Only Then
Because Part D plans come from private insurance companies, you enroll with the plan — not with Social Security. Choose your state to compare the plans we offer and enroll yourself at your own pace.
Want to see every plan in your area? Use the Medicare Plan Finder at Medicare.gov or call 1-800-MEDICARE (TTY 1-877-486-2048), 24 hours a day.
If you go 63 days or more in a row without Part D or other creditable drug coverage after your first window ends, a penalty is added to your premium — usually for as long as you have Part D. It's 1% of the national base premium ($41.33 in 2027) for each full month you went without coverage.
Estimate only, using the 2027 national base premium of $41.33, rounded to the nearest 10¢ as Medicare does. The base premium changes each year, so the dollar amount does too. Medicare makes the final decision. People with Extra Help don't pay this penalty.
Hospital insurance — premium-free for most people. Read the Part A guide →
Doctors and outpatient care — and timing matters. Read the Part B guide →
Our free seminar explains how Medigap, Medicare Advantage and Part D fit together. Watch the seminar →
No pressure · No sales calls · Your choice, your pace
Common Questions
Premiums vary by plan, and some are $0. In 2027, no standard plan can have a deductible higher than $700, you generally pay about 25% of drug costs after that, and your out-of-pocket costs for covered drugs are capped at $2,400 for the year. People with higher incomes also pay an income-related amount to Medicare.
Many people sign up anyway. If you don't have other creditable drug coverage and you skip Part D, you could pay a lifelong penalty if you join later. A low-premium plan protects you if your health changes.
Usually not. Parts A and B can be automatic, but Part D is offered by private plans, so you choose and join one yourself. People with both Medicare and Medicaid, or with Extra Help, may be placed in a plan if they don't choose one.
Yes. During Open Enrollment, October 15 to December 7, you can switch to a different plan. Your new coverage starts January 1. Plans change their costs and drug lists every year, so it's worth reviewing yours each fall.
Drug coverage that's expected to pay, on average, at least as much as standard Medicare drug coverage. Your employer, union or other plan tells you each year whether your coverage is creditable. If it is, you can delay Part D without a penalty.
Yes. Each month's supply of a covered insulin costs no more than $35 under Part D, and the deductible doesn't apply.
Still have a question? Just ask.
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