What Is Medicare Part D? A 2026 Guide to Prescription Drug Coverage

Original Medicare (Parts A and B) covers hospital stays and doctor visits — but not most prescription drugs. That's where Medicare Part D comes in. Part D is optional drug coverage sold through private insurers approved by Medicare.

How Part D Works

Each Part D plan has a formulary — a tiered list of covered drugs. Lower tiers mean lower copays. In 2026, the annual out-of-pocket cap for Part D is $2,000, so once you hit that amount, covered drugs cost you nothing for the rest of the year.

When to Enroll

Enroll during your Initial Enrollment Period when you first become Medicare-eligible, or during Annual Enrollment (Oct 15 – Dec 7). Delaying without creditable employer drug coverage triggers a permanent late penalty added to your monthly premium.

Standalone Part D vs. Medicare Advantage

If you carry Original Medicare with a Medigap supplement, add a standalone Part D plan. Medicare Advantage plans (MAPD) typically bundle drug coverage in — confirm before enrolling.

How to Compare Plans

The best plan depends on your specific medications. Use Medicare's Plan Finder at Medicare.gov, or work with an independent broker who can run your drug list against every plan in your zip code.

Need help comparing Part D options? Wisler is an independent broker who compares every available plan in your area — at no cost to you.