Medicare Part D is prescription drug coverage. Most Medicare Advantage plans include Part D (called MAPD plans). Part D works through a formulary — a list of covered drugs organized into tiers, where Tier 1 generics cost the least and Tier 5 specialty drugs cost the most.

2025 key change (IRA): After you spend $2,000 out of pocket on covered drugs, your cost is $0 for the rest of the year. This is a major improvement for people on expensive medications.

Drug deductibles vary by plan: some waive the deductible entirely; others charge up to the $590 maximum for 2025.