The Inflation Reduction Act’s (IRA) Part D redesign provisions went into effect on January 1, 2025, fundamentally restructuring cost-sharing corridors and upsetting the marketplace. By increasing plan and manufacturer liability, particularly in the catastrophic phase, this legislation intended to lower the financial burden on beneficiaries.
When the IRA passed, the commonly held hypothesis in the marketplace was that Part D plans would attempt to offset their new risk by demanding additional rebates from manufacturers. However, the reality of the redesign has triggered a very different chain of events and patients are feeling the effects.
The Actuarial Reality: A Shift in CMS Support
Under the new structure, manufacturers now share 20% of catastrophic coverage, while Part D plans share 60%. Previously, these corridors required nonexistent or minor cost-sharing from these stakeholders.
More importantly, the Centers for Medicare and Medicaid Services (CMS) radically altered how it supports the Part D market. Under the old design, CMS provided roughly 80% reinsurance in the catastrophic phase. Now, that backstop has been drastically reduced and replaced with upfront direct subsidies to the plans. While the financial support is still there, the risk is now entirely upfront.
The Market Reaction: Plans Exit Over Manufacturer Pushback
Because these upfront subsidies directly increase risk for the plans, predicting exposure for high-cost specialty drugs has become incredibly difficult. Faced with unpredictable actuarial models, Part D plans are not trying to push the cost burden onto manufacturers or fighting for better margins. Instead, many are simply choosing not to participate. The risk burden is too high, leading to a mass exodus of plans from the market.
The Unintended Consequence: Shifting Liability to the Patient
This mass exodus (801 stand-alone PDP in 2023 down to just 360 in 2026) proves that changes to a complex system will always be offset at some juncture. With fewer plans in the market and higher systemic risk, the stakeholder that is ultimately being penalized is the patient.
To mitigate the massive liability shifts, remaining plans are driving up patient out-of-pocket responsibilities through higher coinsurance rates and tighter access. Despite the IRA’s intent to eliminate affordability barriers, the real-world dynamic has inadvertently placed a heavier financial burden on patients.