The $2,100 Cap and the Smoothing Gap: Turning Part D Redesign Into an Adherence Opportunity

The Inflation Reduction Act (IRA) introduced two distinct changes to Medicare Part D drug costs, reshaping how members pay for their prescriptions. The Part D out-of-pocket cap set a hard ceiling on annual drug costs: $2,000 in 2025, rising to $2,100 in 2026. At the same time, the Medicare Prescription Payment Plan, often called “smoothing,” changed the timing of those costs by letting members spread them into monthly installments instead of paying in one lump sum.

Together, the two provisions mark the most significant Part D redesign since the program began in 2006, changing not just how much members pay, but when and how they experience that cost.

However, participation in the payment plan has lagged behind expectations. That’s partly because enrollment isn’t automatic or built into the point of sale. Someone has to proactively identify eligible members and reach out to them, and that responsibility sits with health plans, rather than CMS itself or the pharmacy counter.

In this article, we’ll explore how pharmacist-led medication therapy management (MTM) provides a way to find those members, support adherence as cost barriers shift, and protect Star Ratings adherence measures in the process.

The Participation Gap

According to Milliman’s analysis of 2025 Part D claims data, the payment plan is running well behind its intended reach:

• Participation is stalling. Only 0.6% of all Part D members opted into the payment plan as of July 2025. This is the case even among the people CMS says benefit most (non-low-income members with big specialty drug costs), with their participation at 6.7%.
• There’s no self-service sign-up. Pharmacies must flag the program at $600+ out-of-pocket, but members can’t opt in at the counter. They have to go back to their plan separately, which means plans have to find and reach these members themselves.
• 2026 tightens the target. The out-of-pocket cap rises to $2,100 and the deductible to $615 (just above the $600 pharmacy notification trigger), so more members will be flagged automatically. In addition, 2025 participants are automatically reenrolled unless they opt out or leave the plan. More eligible members surfacing means more opportunity, and more responsibility, for plans to identify and enroll them.

Health plans are best positioned to close these gaps, and pharmacist-led medication therapy management (MTM) offers a way to do it. The same annual medication reviews used to manage chronic conditions can double as the touchpoint for identifying and enrolling members in the payment plan.

Turning Part D Redesign Into an Adherence Opportunity

Pharmacist-led MTM helps in three specific ways: it can find the members most likely to benefit from the payment plan, support their adherence as cost barriers shift, and protect the Star Ratings measures tied to that adherence.

Finding the members. The members most likely to benefit from the payment plan are those facing high upfront drug costs early in the plan year, and they are often already on a pharmacist’s radar. Because MTM enrollment is built around members with multiple chronic conditions and significant medication spend, that population overlaps closely with the members the payment plan was designed to help. A pharmacist reviewing a regimen during a CMR sees the full cost and complexity picture in one place, which makes the review a natural moment to flag the payment plan and explain how it works. No separate outreach campaign is required. The conversation happens inside a touchpoint the plan is already funding.

Supporting adherence. Cost is one of the most common reasons members stop taking medication, and the risk is highest at the first fill, when a large out-of-pocket charge can arrive without warning. A member who walks away from that first fill may never restart, and the consequences of an abandoned antidiabetic or antihypertensive can compound quietly over months. A pharmacist positioned at the point of dispensing can do more than process a prescription, and a pharmacist completing a CMR can do more than gather a medication list. They can explain that the payment plan spreads the cost rather than adds to it, point the member toward additional financial support resources where those exist, and address the practical concerns that often travel alongside cost. That intervention supports continuity of therapy at exactly the point where many would otherwise drop off from a new medication.

Protecting Star Ratings. CMS measures adherence using Proportion of Days Covered, counting members as adherent when they have their medication on hand for at least 80% of the days in the measurement period. The three Part D adherence measures tied to diabetes, hypertension, and cholesterol medications continue to have a high impact on a plan’s overall rating. Each measure will return to triple weight in MY 2027, as MY 2026 was an implementation year for the sociodemographic status (SDS) risk adjustment. The members a plan keeps adherent today are the ones most likely to remain adherent when the weighting climbs back, which is why this period is better spent building durable adherence than waiting for the measure to regain its full influence. Acting now positions plans to protect performance rather than recover it after the fact.

These three efforts reinforce one another. The same review that identifies a candidate for the payment plan is the one that removes a cost barrier to staying on therapy, and the same adherence it protects is what drives Star Ratings performance. None of it requires a new program. It requires connecting the work that plans are already doing with the annual CMR to become a gateway to the Medicare Prescription Payment Plan, a benefit that is already in place, and medication adherence management, which is the most efficient kind of opportunity a plan can act on.

To learn how Clarest can help strengthen your adherence strategy, contact us today.