Medicare Part D: How the Drug Cost Cap Works

1The dates that decide your drug costs

Swipe sideways to see the whole table.

The rest of this guide explains each of those moments, starting with the change that has made Part D far more predictable.

2Why the cap changes the calculation

Since 2025, Part D works in three stages, and the old coverage gap, or donut hole, is gone:

1. Deductible: you pay the full cost of covered drugs until you reach the plan's deductible, no more than $615 in 2026. Many plans set a lower deductible or none, at least for cheaper tiers.
2. Initial coverage: you then pay copays or coinsurance of no more than 25 percent of each covered drug's cost, on average.
3. Catastrophic coverage: once your out-of-pocket spending reaches $2,100, covered drugs cost you nothing for the rest of the year.

Covered insulin costs no more than $35 for a month's supply, with no deductible, and adult vaccines such as shingles and Tdap cost nothing. Some drugs given in a doctor's office or for dialysis are covered under Part B instead. The cap and deductible rise each year: for 2027 the cap is $2,400 and the maximum deductible $700.

3Who the cap helps most

The cap is a big change for some people and almost invisible to others.

• If you take one or more expensive brand-name or specialty drugs, the cap is the headline. Your spending now stops at $2,100 a year, often by midsummer, where before it could run to many thousands.
• If you take a few low-cost generics, you may never come near the cap. For you, the premium, the deductible and the copay on each drug matter far more, and the cheapest total cost may come from a different plan than the one with the lowest premium.
• If a new diagnosis is possible, the cap is insurance against the worst case, which is one more reason not to go without coverage.

Whichever group you are in, the plan finder's estimate of total yearly cost, with your actual drugs entered, is the number to compare.

4What counts toward the cap, and what does not

What you pay for covered drugs counts: the deductible, copays and coinsurance. Payments others make for you count too, including Extra Help, state pharmaceutical assistance programs, AIDS drug assistance programs, many charities and family members.

Your premium does not count. Neither do drugs your plan does not cover, drugs bought outside the network without a good reason, or prescriptions paid with a discount card instead of your plan. It is tempting to use a coupon when it is cheaper at the register, but those dollars do not move you toward the cap. Use your plan card at a network pharmacy so every dollar counts.

5If you miss your first chance: the late penalty

If you go 63 days or more in a row without Part D or other creditable drug coverage after your initial enrollment period, a late enrollment penalty is added to your premium for as long as you have Part D. It is 1 percent of the national base premium, $38.99 in 2026, for each full month without coverage, so 14 months without coverage adds about $5.50 a month, for life.

Taking no prescriptions is not a reason to skip coverage. Many people choose a low-premium plan at 65 precisely to avoid the penalty if their health changes. Coverage from a current or former employer, a union, TRICARE or the VA may count as creditable, which lets you skip Part D without a penalty; your plan sends a yearly notice saying whether it does, so keep it. Before dropping employer coverage to join Part D, check whether that would also end your medical coverage. Our guide to Medicare sign-up deadlines covers the timing around 65.

6Every fall: checking your plan before December 7

Plans change their drug lists, tiers, pharmacies and prices every year, and staying put is a decision too. Each September your plan sends an Annual Notice of Change; read it. Then, during October 15 to December 7:

1. Enter every drug you take, with the dose, and your preferred pharmacies into Medicare's plan finder.
2. Compare the estimated total yearly cost of each plan, premiums plus drug costs, not just the premium.
3. Check that each drug is on the formulary, which tier it is in, and whether prior authorization, step therapy or quantity limits apply.
4. Check whether your pharmacy is preferred, which can lower copays.

If you are also deciding between Original Medicare and Medicare Advantage, see Original Medicare and Medicare Advantage. Your State Health Insurance Assistance Program offers free, unbiased help comparing plans.

7Spreading the cost through the year

The Medicare Prescription Payment Plan lets you pay your drug costs in monthly bills from your plan instead of all at once at the pharmacy. It is free, offered by every Part D plan, and you can join at any time by contacting your plan; since 2026 many people who used it are renewed automatically.

It does not lower what you pay overall; it changes when you pay. For Helen, joining in January would turn a $711 January bill into payments of about $175 a month across the year. It helps most when one expensive prescription early in the year would strain a monthly budget, and least when costs are low and steady.

8If a drug you need is not covered

When you first join a plan, it must give you a temporary supply, usually for a month, of a drug you already take that is not on its list, so you have time to switch or ask for an exception. You or your doctor can request a coverage exception, and if the plan says no, you can appeal. A doctor's statement that other drugs would not work for you carries the most weight, and if your health could be seriously harmed by waiting, you or your doctor can ask for a fast decision. Moving out of your plan's area, or into or out of a nursing home, also opens a special enrollment period to change plans.

9Help with costs, and lower negotiated prices

If your income and savings are limited, Extra Help pays most of your Part D premium, removes the deductible, caps copays at $12.65 per covered drug in 2026 and removes the late penalty; see Medicare Savings Programs and Extra Help.

Since January 2026, Medicare-negotiated prices also apply to the first ten drugs selected under the drug price negotiation program, including widely used medicines for diabetes, heart failure and blood clots. If you take one, your cost at the pharmacy may be lower than before, which also slows how fast you reach the deductible and cap. For how drug coverage fits with the rest of Medicare, see Medicare and Medicaid.