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Medicare’s $2,100 Drug Cap Sounds Great, but Millions of Seniors Are Being Caught off Guard by These Gaps

Understanding these gaps could help you avoid their high price tag.

By Chris Kissell , Edited by Laura Hohenstein

Updated June 25, 2026

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If you are enrolled in Medicare Part D, you probably appreciate the $2,100 drug cap that is part of the program. On the surface, such a rule appears to be a great help in maintaining your financial fitness.

But look a little deeper, and you might learn that the cap is not all it's cracked up to be. Learn more about the gaps that catch people off guard.

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What is the cap?

The Medicare Part D drug cap puts an annual ceiling on the out-of-pocket costs you owe for prescription drugs. Once you hit this cap, your plan pays 100% of the costs of covered medications.

In 2026, the cap is $2,100, up from $2,000 in 2025.

The higher cap arrives in the wake of the elimination of the so-called "donut hole," which was also known as the "coverage gap." This was a temporary phase in Part D coverage where there was a limit on how much your plan would cover drug costs.

Now that the donut hole has disappeared, there are three coverage phases instead of four. They are:

Deductible
Initial coverage
Catastrophic coverage

The same cost-sharing remains in place from the moment you hit your deductible until you reach your cap.

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The catch that undermines the cap

The prescription drug cap is a great thing if it helps reduce the cost of the medications you need. Unfortunately, the cap only applies to drugs that are specifically listed on your plan's formulary.

That means that if you need a specific drug and it is not on the formulary, your costs for the medication could be high. You could ask your doctor to prescribe formulary-listed drugs where clinically appropriate. In addition, the cap does not apply to Medicare Part B drugs. These include injectables and infused drugs.

Finally, you may need prior authorization or "step therapy" before some drugs are covered. This might be true even if the drug is on the formulary. Step therapy refers to a process of being required to try a less expensive drug before you "step up" to a more expensive alternative. Such rules mean you may face delays or extra out-of-pocket costs with some medications.

Other gaps that undermine the cap

There are other "gaps" in coverage that also undermine the coverage cap, at least to a certain degree.

These gaps increase your out-of-pocket costs. Here are some important gaps to keep in mind.

Per-prescription co-pay increases

Some plans are increasing per-prescription co-pays. That means your monthly costs might increase even if annual costs do not.

This is a big issue for Medicare enrollees who are on tight monthly budgets.

The cap doesn't apply in a doctor's office

Medicare Part B offers coverage for drugs that are administered in a doctor's office by a physician, nurse, or other health care provider. This may include cancer drugs and injectable medications.

The Part D drug cap does not apply to such medications.

Your drugs may no longer get coverage in the same tier

Each year during Medicare open enrollment, beneficiaries shop around for the Medicare plan that best suits their needs. This period begins in the fall. It is important to keep on top of which medications your plan does and does not cover. It is also crucial that you pay attention to which tier your drugs fall into.

Many Medicare plans slot medications into different tiers. In general, the lower the tier, the less the drug costs you. It is possible for a drug to move from one tier to another within a plan over time. If you are unaware of this shift, you might be surprised to find you must pay more for the drug than you expected.

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How to avoid higher costs

To no one's surprise, the cost of goods and services often tends to rise as the years roll along. That is also true of prescription drugs. Your Medicare plan may increase the cost of the drugs you need. Or, it may decide to stop covering some drugs altogether.

As a consumer, it is crucial that you stay on top of pricing trends. The federal government urges you to shop around and compare drug plans during open enrollment so you find a plan that offers the medications you need at the lowest price. When comparing plans, check whether your pharmacy is listed as a preferred pharmacy, since many Part D plans offer lower copays at in-network preferred locations.

Medicare open enrollment is the perfect time to compare plans. It runs from Oct. 15 to Dec. 7. You may also want to consider enrolling in the Medicare Prescription Payment Plan, which allows you to spread your out-of-pocket drug costs into predictable monthly installments rather than paying large amounts upfront at the pharmacy counter. The program doesn't reduce your total costs, but it could make budgeting easier.

Bottom line

The Medicare drug cap helps you stretch your retirement dollars further by capping your out-of-pocket medication costs. However, there are a few gaps in the cap that may push your costs higher than you think.

Fortunately, learning more about these gaps helps you to formulate the right plan for keeping such expenses in check. Educating yourself today allows you to be ready to make smarter choices when Medicare open enrollment kicks off in the fall.

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