Medicare Part D 2026: How Prescription Drug Coverage Works
Medicare Part D is prescription drug coverage offered through private insurance plans approved by Medicare. You can get it as a standalone Prescription Drug Plan (PDP) added to Original Medicare, or bundled into most Medicare Advantage plans. In 2026, once your out-of-pocket drug spending reaches $2,100, Medicare covers 100% of your covered drug costs for the rest of the year. Plans use a formulary — a list of covered drugs — organized into pricing tiers.
Key Facts
- 2026 out-of-pocket cap
- $2,100 — once reached, you pay $0 for covered Part D drugs the rest of the year
- 2026 maximum deductible
- $615 — no plan may charge more; many charge less or $0
- Initial coverage coinsurance
- 25% of covered drug costs after your deductible, until you hit the $2,100 cap
- Late enrollment penalty
- 1% of the national base beneficiary premium for each full month without creditable coverage — added permanently
- Plan types
- Standalone Prescription Drug Plans (PDPs) pair with Original Medicare; most Medicare Advantage plans include drug coverage
- Enrollment window
- Annual Enrollment Period runs October 15 – December 7; initial enrollment begins when you first become Medicare-eligible
What Is Medicare Part D?
Part D helps pay for prescription drugs. Original Medicare (Parts A and B) does not cover most outpatient prescriptions — Part D fills that gap.
Coverage is provided by private insurers approved by Medicare. The government sets the rules, but plans are administered by insurers, so premiums, formularies, and pharmacy networks vary by plan and region.
Part D is voluntary, but waiting too long without other creditable coverage triggers a penalty. Understanding how it works can save real money — especially now that federal law caps annual out-of-pocket drug costs.
How to Get Part D: PDPs vs. Medicare Advantage
Two main routes. A standalone Prescription Drug Plan (PDP) works alongside Original Medicare — you keep your Medicare card for hospital and doctor visits and add a separate Part D card, paying a premium on top of Part B.
The second route is a Medicare Advantage plan that bundles drug coverage (MAPD). If your Advantage plan includes drugs, you do not need a separate PDP — and generally cannot add one.
Both provide the same federally required benefits. The right choice depends on your medications, pharmacies, doctors, and budget. Compare at Medicare.gov.
Formularies and Drug Tiers
Every Part D plan has a formulary — the list of covered drugs. If your medication is not on it, the plan generally will not pay (though you can request an exception). Confirm your specific drugs are covered before enrolling.
Formularies use tiers that determine your cost: Tier 1 (preferred generics, lowest copay), Tier 2 (non-preferred generics), Tier 3 (preferred brand-name), Tier 4 (non-preferred brand-name), and Tier 5 (specialty drugs, highest cost-sharing, sometimes a percentage of price).
Plans change formularies yearly. During AEP (October 15 – December 7), review your plan's updated formulary to confirm your medications are still covered at an acceptable cost.
The 2026 Coverage Phases and the Out-of-Pocket Cap
The Inflation Reduction Act restructured Part D to be simpler and more protective, eliminating the old 'donut hole' coverage gap. Here is how 2026 works:
Deductible phase: you pay 100% of drug costs until you meet the deductible — no plan may charge more than $615 in 2026, and many charge less or nothing.
Initial coverage phase: after the deductible, you pay 25% coinsurance on covered drugs until your out-of-pocket spending reaches $2,100.
Catastrophic phase: once you hit $2,100, Medicare covers 100% of covered Part D drugs for the rest of the year — you pay nothing. Verify current figures at Medicare.gov, as amounts adjust annually.
The Part D Late Enrollment Penalty
If you are eligible and do not sign up for Part D when first eligible — and have no other creditable drug coverage — you may owe a penalty when you enroll later.
It is 1% of the national base beneficiary premium for each full month you went without coverage, added to your premium permanently, even if you switch plans.
Creditable coverage means drug coverage at least as good as standard Part D (employer/union plans, TRICARE, VA, FEHB). Keep the annual notice confirming it. When you lose creditable coverage, you have about 2 months (a special window) to join Part D without penalty.
How to Choose a Part D Plan
Start with your medications — list every drug, dose, and frequency, then use Medicare's Plan Finder at Medicare.gov to enter them and your ZIP code. It estimates your total annual cost per plan (premium plus expected drug costs) and shows whether each drug is covered.
Check pharmacy networks — using a preferred pharmacy can lower copays significantly. Confirm a pharmacy you can use is in-network and preferred.
Look beyond the premium — a $0-premium plan may charge more per prescription. Compare total estimated annual cost, not just the monthly premium.
Review plan changes every year during AEP (October 15 – December 7). Even if you like your plan, take 15 minutes each fall to confirm it still works. Availability varies by location.
Extra Help: Lower Costs for Qualifying Individuals
If your income and resources are limited, you may qualify for Extra Help (the Low-Income Subsidy), which can significantly reduce or eliminate Part D premiums, deductibles, and copays. Apply at ssa.gov or call Social Security at 1-800-772-1213 — there is no cost to apply, and you may qualify even without Medicaid.
Your state may also offer a State Pharmaceutical Assistance Program (SPAP). Eligibility varies by state — visit Medicare.gov or call 1-800-MEDICARE for help finding programs where you live.
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Get My Free Plan Review →Frequently Asked Questions
Do I have to sign up for Medicare Part D?
Part D is voluntary, but if you do not enroll when first eligible and have no other creditable coverage, you owe a permanent late penalty. If you take no drugs now, weigh the low cost of a basic plan against the risk of a penalty if your health needs change.
What is the out-of-pocket cap for Part D in 2026?
In 2026 it is $2,100. Once your spending on covered Part D drugs reaches that amount, your plan covers 100% of covered medications the rest of the year. This cap came from the Inflation Reduction Act and replaced the old coverage gap. Verify the current figure at Medicare.gov.
What if my drug is not on my plan's formulary?
The plan generally will not pay. Options: ask your doctor about a covered equivalent, request a formulary exception with your doctor's documentation of medical necessity, or switch plans during AEP. Always check formularies before enrolling.
Can I have both a standalone Part D plan and Medicare Advantage?
Generally no. If your Advantage plan includes drug coverage (MAPD), you cannot add a standalone PDP — doing so may disenroll you from Advantage. A narrow exception exists for the rare Advantage plans without drug coverage.
When can I enroll in or change my Part D plan?
Most people enroll when first Medicare-eligible. After that, the main window is AEP (October 15 – December 7), effective January 1. Special Enrollment Periods apply for events like losing creditable employer coverage. Advantage enrollees also have a January 1 – March 31 Open Enrollment Period.