Medicare Part D Coverage Gap

The Medicare Part D coverage gap was a phase of the standard prescription drug benefit in which the plan's ordinary cost sharing stopped applying and the enrollee paid a much larger share of the price of their drugs. It began once total drug spending for the year passed the initial coverage limit and ended once the enrollee's own out-of-pocket spending reached the annual out-of-pocket threshold, at which point catastrophic coverage took over. The statute's own headings call it the coverage gap; "donut hole" is the phrase everyone actually uses, and it describes the shape of the benefit rather than anything in the law.

The gap is gone. Section 11201 of the Inflation Reduction Act rewrote every provision that created it so that each applies only "for a year preceding 2025," and separately sunset the manufacturer discount program built around it. The current benefit and its annual ceiling on out-of-pocket spending are the subject of the Medicare Part D page. This page explains what the gap was, why it existed, how it was closed, and why so much published material still describes it as though it were live.

The original design, and why a hole appeared in the middle of it. The 2003 law that created Part D built the standard benefit in four stages. An enrollee first paid an annual deductible; then 25 percent coinsurance up to an initial coverage limit measured by total drug spending; then, in the gap, the whole cost of their drugs; and finally, once their own out-of-pocket spending reached an annual threshold, only a small copayment or coinsurance under catastrophic coverage. The 2006 statutory figures show the shape: a deductible of $250, an initial coverage limit of $2,250, and an out-of-pocket threshold of $3,600, each indexed annually thereafter. Congress chose that structure to cover routine spending and catastrophic spending within a fixed budget, and the gap is what the arithmetic left in between.

The 2010 phase-down closed it gradually and by two different mechanisms. The Health Care and Education Reconciliation Act of 2010 added subparagraphs (C) and (D) to 42 U.S.C. 1395w-102(b)(2), which set the enrollee's share inside the gap on a declining schedule. For generic drugs the statute fixed the "generic-gap coinsurance percentage" at 93 percent for 2011, falling by 7 percentage points a year, and at 25 percent for 2020 through 2024. For brand-name drugs the enrollee's share was the "applicable gap percentage" minus a manufacturer discount, and the applicable percentage stepped down from 97.5 percent for 2013 and 2014 to 75 percent for 2019 through 2024, leaving a 25 percent share once the discount was subtracted. Alongside that, the Affordable Care Act created the Medicare coverage gap discount program at 42 U.S.C. 1395w-114a, under which manufacturers agreed to discount brand drugs dispensed in the gap. The discounted portion still counted toward the enrollee's out-of-pocket threshold, so the discount pushed people through the gap faster as well as making it cheaper.

So "the donut hole closed in 2020" and "the donut hole was eliminated in 2025" are both true, and they mean different things. By 2020 the phase-down had brought the enrollee's share inside the gap down to 25 percent, the same share as the initial phase, so for most people the gap no longer changed the price at the pharmacy counter. It remained a distinct phase in the benefit's accounting, with its own statutory rules and its own manufacturer discount program. What the Inflation Reduction Act did in 2022, effective for 2025, was delete the phase itself. The initial coverage limit now applies only "for each of years 2007 through 2024"; the generic and brand gap coinsurance provisions apply only "for a year preceding 2025"; and the coverage gap discount program "shall not apply with respect to applicable drugs dispensed on or after January 1, 2025," replaced by the manufacturer discount program at 42 U.S.C. 1395w-114c.

The provisions are still printed in the United States Code, which is why the old explanation survives. Congress did not strike the gap paragraphs; it limited each of them to years that have passed. A reader who opens the statute today finds the initial coverage limit, the generic-gap coinsurance percentage and the applicable gap percentage sitting on the page, each carrying a date restriction that is easy to skim past. Guidance, plan comparison tools and consumer articles written before 2024 reproduce the four-phase picture in the present tense, and CMS's own current Part D costs page no longer uses the words "coverage gap" or "donut hole" at all, so a reader who arrives with the phrase gets no answer from the agency that ran it.

How the four stages ran, in the years the gap existed:

1. Deductible. The enrollee paid the plan's annual deductible in full on covered drugs.

2. Initial coverage. Above the deductible the enrollee paid 25 percent coinsurance, or the plan's actuarially equivalent tiered cost sharing, until total drug spending by the enrollee and the plan together reached the initial coverage limit.

3. The coverage gap. From that point the plan's ordinary cost sharing stopped. Before 2011 the enrollee paid the whole negotiated price; from 2011 the phase-down and the manufacturer discount reduced that share year by year.

4. Catastrophic coverage. Once the enrollee's own out-of-pocket spending reached the annual out-of-pocket threshold, cost sharing dropped to a small copayment or coinsurance for the rest of the year.

A hypothetical set in 2006, using that year's statutory figures. Ivan's drug costs run steadily through the year. He first pays the $250 deductible. Between the deductible and the $2,250 initial coverage limit there is $2,000 of spending, on which he pays 25 percent, or $500. So at the moment he enters the gap he has paid 250 + 500 = $750 of his own money.

The threshold that ends the gap is measured by his own spending, not by total spending, and in 2006 it was $3,600. He therefore has to pay another 3,600 − 750 = $2,850 entirely himself before catastrophic coverage begins, which happens when total drug spending reaches 2,250 + 2,850 = $5,100. That $2,850 stretch, with no help from the plan, is the donut hole. The figures are the 2006 statutory ones and are historical; they were indexed every year afterwards and the phase no longer exists.

Why the design was defended

• It let the 2003 benefit cover both routine and catastrophic drug spending within a fixed budget, which a benefit with no gap could not have done at the same premium.
• It concentrated federal help at the two ends of the distribution, where most enrollees and the sickest enrollees respectively sit.
• Enrollees receiving the low-income subsidy had their cost sharing set by that subsidy rather than by the standard benefit, and the statute excluded them from the coverage gap discount program on exactly that ground.

Why it was closed

• The share fell on people in the middle of the spending distribution, often those with a chronic condition and a single expensive drug.
• It arrived mid-year and without warning for anyone who had not modeled their own spending, so the price of an ongoing prescription could jump at the point in the year when spending was already highest.
• The four-phase structure was genuinely hard to explain, and the confusion it created outlived the gap itself, since much published guidance still teaches it.
• Congress legislated against it twice, first phasing the enrollee's share down across a decade and then deleting the phase outright, which is a fair summary of how the design was eventually judged.