Trends in Dual-Eligible Enrollees' Access to Drugs Under Part D, 2011-2025

Trends in Dual-Eligible Enrollees' Access to Drugs Under Part D, 2011-2025

Issued on 12/12/2025 | Posted on 12/17/2025 | Report number: OEI-05-25-00350

Report Materials

• Full Report (PDF, 1.5 MB)
• Report Highlights (PDF, 304.4 KB)

Why OIG Did This Review

• For dual-eligible enrollees-that is, people enrolled in both Medicare and Medicaid-access to prescription drugs is particularly important. Overall, they have very low incomes and-because they are more likely to be in poorer health than other people enrolled in Medicare-tend to use more Medicare services.
• After prescription drug coverage for dual-eligible enrollees shifted from Medicaid to Medicare Part D, Congress mandated that OIG study whether Part D formularies cover prescription drugs commonly used by dual-eligible enrollees. OIG has produced an annual report pursuant to this mandate for the last 15 years (from 2011 to 2025).
• In this data snapshot, we present trends across our annual analyses of Part D formulary coverage of the top 200 drugs used by dual eligibles to summarize our findings for Congress and the public.

What OIG Found

• Most Part D plan formularies have covered almost all of the drugs that dual-eligible enrollees commonly use since 2011, and coverage has been consistently high over the last decade.

• The number of commonly used drugs covered by all formularies steadily increased since 2011, and only a small number of commonly used drugs were not covered by most formularies.

What OIG Concludes

In general, over the last 15 years dual-eligible enrollees had-and continue to have-access to the drugs they most commonly use, regardless of the Part D plan in which they enroll.