Part D prescription drug plans

How Part D works

Part D prescription drug plans are offered by private companies approved by Medicare. A stand-alone Part D plan pairs with Original Medicare, with or without a Medigap policy. Most Medicare Advantage plans include drug coverage built in.

Formularies and pharmacies

Each plan has a formulary — a list of covered drugs, often organized into tiers — along with a network of pharmacies, sometimes with preferred pharmacies that offer lower costs. Formularies, pharmacy networks, and costs can all change from one year to the next.

What it costs

Part D costs can include a monthly premium, a yearly deductible, and copayments or coinsurance depending on the plan and the drug.

Since 2025, Part D includes a yearly cap on out-of-pocket costs for covered drugs. The exact amount is set each year — visit Medicare.gov for the current figure.

The Medicare Prescription Payment Plan is another option: it lets you spread your out-of-pocket drug costs into monthly payments across the year instead of paying them all at the pharmacy.

Higher-income premiums

If your income is above a certain level, you may pay an extra amount for Part D, known as IRMAA. Read more about how IRMAA works.

Enrolling on time

If you go 63 or more days in a row without Part D or other creditable drug coverage after your Initial Enrollment Period ends, a penalty may be added to your Part D premium for as long as you have Part D coverage. Employer coverage can count as creditable coverage — ask your employer or plan for a creditable coverage notice so you have it on hand.

Help paying for Part D

Extra Help is a Medicare program that helps people with limited income and resources pay their Part D costs. You can apply through the Social Security Administration at ssa.gov.

How I can help

I compare Part D plans using your exact prescriptions and pharmacies, every fall — the plan that fit you last year may not fit next year. Schedule a review and bring your medication list.