Medicare Part D’s Cap Rises to $2,400 in 2027. One Specialty Drug Can Hit It by February, but the Premium Never Stops

Picture a 68-year-old retiree on one self-administered rheumatoid arthritis drug covered under Medicare Part D. The drug’s annual cost runs into five figures. She fills the first prescription in January, works through her deductible, fills again in early February, and sometime that month her out-of-pocket spending reaches the annual cap. From then through December 31, she owes $0 for covered Part D fills.

What she does not stop paying is the premium. It bills every month, it sits outside the cap, and it’s the one line on the brochure that behaves exactly the way she expected.

What Changed for 2027

CMS raised the Part D annual out-of-pocket cap to $2,400 for 2027, up from $2,100, and lifted the standard deductible to $700 from $615. For a healthy enrollee on a few generics, premium shopping works fine. She’ll never approach the cap, so a low premium is close to the whole decision.

For someone on a specialty drug, the ranking changes but the premium doesn’t vanish from it. Her covered-drug spending lands at roughly the cap either way, assuming no Extra Help or other assistance. What differs between plans is whether the drug is covered at all, what she has to clear to get it filled, and what she pays in premiums across twelve months on top of that capped amount.

What Actually Moves Her Total

Three things decide her year, and premium is a fourth that never disappears. Formulary inclusion comes first. If the plan doesn’t cover the drug, the cap never engages, because amounts paid outside the Part D benefit generally don’t count toward it. A cheaper premium on a plan that excludes the molecule is the worst outcome available.

Tier placement and utilization management come next. Specialty tier coinsurance, prior authorization and step therapy can delay a fill by weeks, and during that delay she either pays cash or goes without. The deductible matters less than it looks, because deductible spending counts toward the $2,400. A $0-deductible plan and a $700-deductible plan can both deliver her to the same capped total. What changes is when and how she gets there, not where she lands. Then the premium, every month, all year.

Income Adds a Layer

Roughly 8% of Medicare beneficiaries owe an income-related adjustment on top of the plan premium. Under the 2026 brackets, the latest data available, a single filer above $109,000 pays $14.50 extra per month, rising to $91.00 at the top tier, which starts at $500,000 single and $750,000 joint.

The surcharge attaches to whichever plan she picks. It doesn’t erase the premium difference between plans, it sits on top of it, so a cheaper premium still saves her the same amount it would have at any income. If her income is comfortably below $109,000 single or $218,000 joint, none of this enters the decision. IRMAA is one of several surcharges that catch retirees after the fact, and we mapped the rest in a free guide to Medicare’s hidden bills.

The Cash-Flow Problem the Cap Doesn’t Solve

Reaching the cap in February beats paying full price in December, but concentrating that much spending into two months is still a shock on a fixed income.

Every Part D plan must offer the Medicare Prescription Payment Plan, which spreads what she owes across the remaining months of the year rather than demanding it at the pharmacy counter. Medicare calculates each monthly bill from the accumulated balance and the months left, so the amounts shift as new fills are added. They aren’t equal twelfths.

That formula is also why timing matters. Enrolling before the first expensive fill gives the balance the most months to spread across. Enrolling in March gives it fewer.

Annual Enrollment Actions 

The plan that looks cheapest in October is not always the one that costs least by December, and the gap between those two things is where this decision lives.

1. Run the Plan Finder with your exact drug, not a generic search. Sort by total annual cost rather than premium. For a specialty-drug patient that total is roughly the capped drug spending plus a year of premiums.
2. Confirm the drug appears on the 2027 formulary and check its tier. Call the plan if the listing is ambiguous. A move from tier 4 to tier 5, or off formulary entirely, resets everything.
3. Enroll in the Medicare Prescription Payment Plan before your first expensive fill. The earlier the balance starts spreading, the more months it has to spread across.

The premium is the first amount the eye finds on a plan brochure. For someone on one specialty drug it isn’t the most important data point, but it’s the one that keeps arriving after the cap has stopped everything else.

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