Health Law Daily Wrap Up, MEDICARE PART D—OIG Reports: Plans generally cover most drugs commonly used by dual-eligible enrollees, (Jul 6, 2026)

By Erick Jorgenson

A majority of the benchmark plans’ formularies, six of eight, covered at least 97% of the most commonly used drugs while the remaining two covered at least 95%.

The HHS Office of Inspector General reviewed drug coverage under Medicare Part D for all dual-eligible enrollees, people enrolled in both Medicare and Medicaid, finding that of the 327 distinct formularies used by Part D plans in 2026, 315 covered at least 97% of commonly used drugs. This annual finding is consistent with previous years going back to 2011, and the OIG concluded dual-eligible enrollees can expect to have access to most drugs, regardless of the Part D plan (OIG Report, No. OEI-05-26-00150 (July 2, 2026)).

Results. Each year, CMS identifies benchmark plans, which are Part D plans with premiums at or below a regional benchmark amount per the Social Security Act § 1860D-14(b) and 42 C.F.R. § 423.780(b)(2)(i). CMS identified 86 benchmark plans which used eight distinct formularies. Of these formularies, six of eight covered at least 97% of the most commonly used drugs while two formulary lists covered at least 95%.

This finding is significant as dual-eligible enrollees do not pay premiums for the plans due to Medicare subsidies determined by region, and because “[w]hen CMS randomly assigns dual-eligible enrollees to Part D plans, it assigns them to benchmark plans without considering their specific prescription drug needs.” CMS randomly assigns dual-eligible enrollees to a Part D plan with premiums below a regional benchmark when (1) the enrollee becomes eligible for Medicare and Medicaid, but have not elected a Part D plan, (2) the enrollee’s current Part D plan will have a premium above the regional benchmark the following year, or (3) the plan is terminated as per CMS, MA and Part D Enrollment and Disenrollment Guidance.

Small number not covered. Dexlanscoprazole, which is used to treat gastroesophageal reflux disease, and Insulin Degludec, which is used to treat diabetes, were covered by fewer than 75% of formularies in 2026. In fact, Dexlanscoprazole is only covered by 13% of formularies. However, the formularies did cover at least two “alternative drugs in the same respective therapeutic classes” per 42 C.F.R. § 423.120(b)(2), as required by CMS. Further 190 other commonly used drugs had coverage by over 75% of formularies, 187 drugs had coverage in over 90% of formularies, 181 drugs had coverage by over 95% of formularies, and 168 drugs were covered in all formularies.

While dual-eligible enrollees have several options if the formularies do not cover the needed drugs, the options require the enrollees to take administrative action and “do not guarantee that [the enrollee can] get the drugs.” Dual-eligible enrollees have one chance per month to switch to plans that cover the prescription drug required, but not to all plan types. They can take part in an exceptions and appeals process to request coverage of nonformulary drugs. In addition, they can work with their prescribers to find an alternative drug that is covered. Finally, another alternative is that the enrollees can pay out of pocket. That said, people enrolled in both Medicare and Medicaid tend to have “very low incomes” and are “more likely to be in poorer health than other people enrolled in Medicare” so these remedies may be infeasible and burdensome in certain circumstances.

Methodology. The OIG used the 2023 Medicare Current Beneficiary Survey (MCBS) Cost and Use data to create the list of drugs with “the highest utilization by dual-eligible enrollees.” Further, “dual-eligible enrollees” meant “all dual-eligible enrollees, rather than only full-benefit dual-eligible enrollees as specified by the mandate.” In addition, the OIG used the February 2026 First DataBank National Drug Data File to identify drug product information.

In determination of the drugs most commonly used by dual-eligible enrollees, the OIG created a list of all drugs reported by dual-eligible enrollees surveyed in the 2023 MCBS, excluding territories. Then the OIG collapsed the list to “a list of drugs based on their active ingredients” and then ranked the drugs based on frequency of use, accounting for the weight from the MCBS. Finally, of the top 200 drugs, only 192 drugs were used to review, as 7 are not covered under Part D, and 1 drug (Lanthanum Carbonate) did not have enough data to confidently project use to the entire population.

Moreover, the OIG collected from CMS the formulary and plan data for Part D plans operating in 2026 and analyzed each unique formulary to determine the rates of inclusion. A drug was counted as included if the formulary included the active ingredient.

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