How CMS’s 2025 Medicare Part D redesign affects Wegovy and Zepbound coverage under the new weight loss drug exclusion rules

How CMS’s 2025 Medicare Part D redesign changes the outlook for Wegovy and Zepbound under new weight loss drug rules

The Centers for Medicare & Medicaid Services (CMS) finalized major updates to Medicare Part D starting January 1, 2025. The new structure trims out-of-pocket spending for beneficiaries and cleans up which drugs remain excluded. One area that stands out, anti-obesity drugs, specifically Wegovy (semaglutide, Novo Nordisk) and Zepbound (tirzepatide, Eli Lilly).

Part D Redesign Highlights

For 2025, the old coverage gap or “donut hole” disappears. Once beneficiaries spend $2,000 in total on brand and generic drugs, they hit a hard cap for the year. CMS says this setup makes costs more predictable while shifting more financial exposure to Part D plans and drug makers. Clear enough on the math, but not every drug gets to take part. Section 1927(d)(2) of the Social Security Act still blocks Medicare from covering medications “for anorexia, weight loss, or weight gain.” That clause stays put.

Comparison of Coverage Rules

What this means for Wegovy and Zepbound

Both Wegovy and Zepbound are GLP-1 receptor agonists approved for chronic weight management, not diabetes. That detail matters. Because of their labeling, they remain off-limits for Medicare Part D and Medicare Advantage formularies. The GLP-1 versions used to treat diabetes, like Ozempic (semaglutide) and Mounjaro (tirzepatide), stay on formularies, typically in Tier 3 or 4 depending on the plan.

Here’s where it gets messy. Some private Medicare drug plans might technically keep Wegovy or Zepbound on file if a physician prescribes them off-label for diabetes treatment, but CMS made clear in a 2023 memo that those claims won’t be reimbursed. So, for now, beneficiaries hoping to use these meds must rely on employer coverage, a commercial plan with anti-obesity benefits, or pay full price. KFF data show the average retail cost of Wegovy was over $1,300 per month in 2024, real money for most retirees.

Look, as someone who reviews formularies for a living, I’d say the contradiction here, covering the same active molecule under one label but not another, is frustrating. But until Congress changes that exclusion language, CMS can’t do much even if policy sentiment shifts.

Medical and insurance disclaimer: This content is for informational use and does not provide medical advice or a coverage determination. Beneficiaries and plan sponsors should confirm details with their insurer and talk with licensed professionals about treatment and reimbursement questions.