Medicare Part D Coverage Gap (Donut Hole) Fully Explained

If you have Medicare drug coverage and your prescription costs have suddenly jumped mid-year, you may have entered what's commonly called the "donut hole" — a coverage gap built into Medicare Part D's benefit structure. It catches a lot of people off guard, but once you understand how it works, you can plan around it.

What Is the Medicare Part D Coverage Gap?

Medicare Part D — the prescription drug benefit — doesn't work like a simple deductible-then-coverage plan. Instead, it moves through distinct phases, and the coverage gap is one of them.

Here's how the phases work in sequence:

The coverage gap is the third phase — the stretch between the end of your initial coverage and the start of catastrophic coverage. Historically, beneficiaries paid a much larger share of drug costs during this phase. That's where the term "donut hole" came from: there was a hole in protection between two layers of coverage.

How Did the Donut Hole Change Over Time?

The coverage gap used to be a serious financial shock. Beneficiaries who hit it faced paying full price for drugs with no plan assistance. The Affordable Care Act began closing the donut hole gradually, and by 2020, most beneficiaries paid no more than 25% of drug costs while in the gap — the same coinsurance rate as the initial coverage phase.

Starting in 2025, a significant structural change took effect under the Inflation Reduction Act: a hard cap was placed on out-of-pocket drug costs for Medicare Part D enrollees. Once a beneficiary's out-of-pocket spending reaches that annual cap, they pay nothing for covered drugs for the rest of the year. This effectively transforms how the catastrophic phase functions and reduces the financial exposure that previously defined the donut hole era.

What Counts Toward the Coverage Gap Threshold?

Not every dollar you spend on prescriptions counts the same way. Understanding what counts toward moving through the phases matters.

Amounts that typically count toward your spending thresholds include:

• Your plan's payments for covered drugs
• Your own out-of-pocket payments for covered drugs
• Manufacturer discounts on brand-name drugs (in some phases)

Amounts that typically do NOT count:

• Premiums you pay for Part D coverage
• Costs for drugs not on your plan's formulary
• Costs paid by other coverage (like a third-party insurer)
• Payments made by someone else on your behalf (with some exceptions)

The interaction between these categories is more nuanced than it appears, which is why two people with similar-looking drug lists can hit the gap at very different points in the year.

Who Is Most Likely to Reach the Coverage Gap?

Not every Part D enrollee enters the donut hole. Several factors determine whether — and how quickly — you get there:

• Number of prescriptions — The more drugs you take, the faster spending accumulates
• Drug tiers — Brand-name and specialty drugs carry much higher costs than generics
• Formulary placement — How your plan classifies your specific drugs affects your cost-sharing
• Early-year refills — Filling a 90-day supply early in the year accelerates spending
• Plan design — Plans vary in their deductible amounts, tier structures, and initial coverage limits

People managing multiple chronic conditions, taking specialty medications, or relying on brand-name drugs with no generic equivalent are generally more likely to reach the gap than someone taking a handful of low-cost generics.

Strategies People Use to Manage Costs in the Gap 💊

While this article can't assess what's right for your situation, these are the approaches beneficiaries commonly explore:

Ask about generics or therapeutic alternatives. If a brand-name drug is driving you toward the gap, your prescriber may be able to discuss whether a lower-cost alternative is clinically appropriate for you.

Look into Extra Help (Low Income Subsidy). Medicare's Extra Help program assists qualifying beneficiaries with Part D costs, including during the coverage gap. Eligibility is based on income and assets.

Review your plan during Open Enrollment. Plans vary significantly in how they structure drug tiers and cost-sharing. A plan that looked like a good fit in October may not be optimal if your drug regimen changes.

Explore manufacturer patient assistance programs. Some pharmaceutical companies offer assistance programs for people who take their drugs and have high out-of-pocket costs. Eligibility criteria vary widely.

Track your spending. Knowing approximately where you are in your benefit phases lets you anticipate — rather than be surprised by — a cost change.

What the Inflation Reduction Act Changed (and What It Didn't)

The out-of-pocket cap introduced for 2025 is a meaningful protection, but it doesn't eliminate complexity. A few things worth understanding:

• Premiums are not capped. The out-of-pocket limit applies to drug costs at the pharmacy, not your monthly Part D premium.
• Formulary gaps still exist. If a drug isn't on your plan's formulary, those costs generally don't count toward your cap.
• Plan designs still vary. Insurers continue to structure their formularies, tiers, and coverage differently, so the experience of reaching the catastrophic phase will differ by plan.

The structural change reduces the worst-case financial exposure for high-cost drug users, but choosing the right plan for your specific drug list remains as important as ever.

What You'd Need to Evaluate for Your Own Situation

Understanding the donut hole landscape is the starting point. Whether it actually affects you — and how much — depends on your specific drug regimen, your plan's formulary and tier structure, your income and whether you qualify for Extra Help, and how your usage patterns unfold across the benefit year.

The Medicare Plan Finder tool at Medicare.gov allows you to enter your actual medications and compare estimated annual costs across available plans in your area. A State Health Insurance Assistance Program (SHIP) counselor can also walk through your specific situation at no cost — they're independent and don't sell insurance.