Most Americans approaching Medicare age believe the biggest financial risk from prescription drug coverage involves hitting the infamous “donut hole”—that coverage gap where beneficiaries once paid full price for medications. What they don’t know could indeed cost them thousands: as of January 1, 2025, the donut hole was eliminated entirely, fundamentally changing how Part D works. But this landmark change has created a dangerous blind spot. Americans are now missing entirely different hidden costs that can accumulate to thousands in unexpected expenses. Consider Maria, age 67, who delayed enrolling in Part D because she thought her employer coverage was sufficient. When she finally enrolled two years later, she discovered a permanent 1% penalty on her monthly premiums—calculated on a government reference amount of $38.99, multiplied by 24 months of non-enrollment—that would stay with her for life.
She had no idea this penalty existed, and she certainly didn’t know that switching plans later wouldn’t erase it. The Medicare Part D landscape of 2026 looks deceptively simpler than it did a year ago, but that simplification masks several costly traps that most beneficiaries encounter too late to avoid them. The out-of-pocket spending cap is now $2,100 for the year, and plans must cap deductibles at $615—sound reasonable until you realize these numbers increase annually and that getting these numbers wrong during enrollment can cost you far more than the difference in premiums. Meanwhile, income-related surcharges affect millions of middle-income retirees, plan options have dwindled from 12-16 to just 8-12 per region, and formulary restrictions determine whether your specific medications are actually covered at all. Understanding these gaps isn’t optional for retirees who want to avoid preventable expenses. The difference between informed and uninformed enrollment can easily reach $3,000 to $5,000 annually, and penalties and surcharges compound year after year. This article walks through what most Americans don’t know about Part D—not because the information is secret, but because it’s complex, scattered across government websites, and rarely explained in plain terms until it’s too late.
Table of Contents
- How Did the Coverage Gap Disappear, and What Replaced It?
- The Permanent Penalty That No One Explains Until It’s Too Late
- Income-Related Surcharges That Hit Middle-Income Retirees Unexpectedly
- Annual Increases That Make Multi-Year Planning Nearly Impossible
- Formulary Restrictions and Reduced Plan Options That Narrow Your Choices
- Switching Plans Won’t Erase Your Late Enrollment Penalty
- The Enrollment Period Trap and Strategic Planning for the Future
- Conclusion
How Did the Coverage Gap Disappear, and What Replaced It?
The elimination of the “donut hole” on January 1, 2025, removed one of medicare part D’s most notorious cost structures. For nearly two decades, beneficiaries who reached a certain out-of-pocket threshold would suddenly face paying substantially higher percentages of their drug costs until catastrophic coverage kicked in. That phase is gone. What Americans don’t always understand is what the 2026 structure actually means for their wallet. Here’s how it works now: after you meet your deductible (maximum $615 in 2026), you enter the “initial coverage phase” where you pay 25% coinsurance on covered drugs. You stay in this phase until your out-of-pocket spending reaches $2,100 for the year. Once you hit that $2,100 threshold, catastrophic coverage takes over, and your plan pays for 60% of remaining covered drug costs for the rest of the calendar year. No gap, no sudden price jump.
On the surface, this sounds fairer. But here’s what most beneficiaries miss: these numbers—the $615 deductible and $2,100 cap—are specific to 2026 only. They increase every year. The 2026 out-of-pocket cap increased from $2,000 in 2025, and the deductible climbed from $590. Beneficiaries who plan on paying $2,100 out-of-pocket in 2027, 2028, and beyond will be shocked to find their costs are higher. Additionally, not all drugs are covered equally. Many Part D plans have tiered formularies where preferred generic drugs cost less coinsurance than brand-name alternatives—sometimes 25% versus 50% or more. A drug removed from the formulary altogether puts the entire out-of-pocket cost on you, immediately affecting how fast you accumulate toward that $2,100 threshold.
The Permanent Penalty That No One Explains Until It’s Too Late
The most dangerous unknown in Medicare Part D is the late enrollment penalty—a permanent surcharge that applies if you don’t enroll when first eligible. Most Americans don’t realize that simply signing up later doesn’t just mean you pay a higher premium for a few months. The penalty lasts for the entire time you have Medicare drug coverage, even if you switch plans or move to different coverage types. The calculation is straightforward but devastating: 1% of the government’s reference amount ($38.99 in 2026) multiplied by the number of months you were eligible but not enrolled. A gap of just two years triggers a $9.36 monthly surcharge. Three years adds $14.04 monthly. At first glance, these numbers seem manageable, but multiply by 12 months and 10 years of retirement, and you’re looking at $1,100 to $1,700 in penalty costs.
The penalty applies if there’s a continuous period of 63 days or more after your initial enrollment period during which you were eligible but didn’t enroll. This catches many people who assume they can wait until they “really need” prescription drugs. One retired accountant delayed enrollment thinking his out-of-pocket prescription costs were low while on his spouse’s health plan. After six months without Part D, he was hit with the permanent penalty. Even after switching to a cheaper plan a year later, the penalty followed him. The only way to avoid the penalty is having “creditable coverage”—meaning prescription drug coverage that’s at least as good as Part D from an employer, military (VA/TRICARE), or certain state programs. Many retirees don’t know this protection exists, and they certainly don’t know that they need to verify their employer coverage actually qualifies as creditable before letting Part D enrollment deadlines pass. Proof of creditable coverage requires documentation, and once you lose it without Part D enrollment, obtaining retroactive proof becomes difficult or impossible.
Income-Related Surcharges That Hit Middle-Income Retirees Unexpectedly
Another major hidden cost comes from income-related surcharges, officially called IRMAA (Income-Related Monthly Adjustment Amount). The 2026 brackets are stark: if you and your spouse file jointly and your 2024 Modified Adjusted Gross Income exceeds $218,000, you’ll pay additional surcharges on top of your base Part D premium. Even at the lowest surcharge bracket—$109,001 to $131,000 for singles or $218,001 to $262,000 for married couples—you’ll pay an extra $14.50 monthly. At the highest bracket, surcharges reach $91 monthly. For a couple in the highest bracket paying $34.50 in base premium, the total monthly cost jumps to $125.50 just for drug coverage. What makes this particularly painful for retirees is that IRMAA calculations use your Modified Adjusted Gross Income from two years prior.
A retiree who had a good income in 2024 will be hit with surcharges in 2026 even if their income dropped in 2025. There’s no real-time adjustment. Additionally, the income threshold doesn’t adjust for inflation in the way most people expect. A couple earning $220,000 in 2026 is still above the threshold, meaning surcharges continue indefinitely. Real estate sales, inherited retirement accounts, or other one-time income events in a prior year can push retirees into surcharge brackets they didn’t expect and can’t easily escape. One retired couple sold their second home in 2024 and unexpectedly found themselves paying IRMAA surcharges throughout 2026—a $1,092 annual surprise expense they hadn’t budgeted for.
Annual Increases That Make Multi-Year Planning Nearly Impossible
The out-of-pocket spending cap and deductible amounts increase annually based on inflation and prescription drug cost trends. The 2026 cap of $2,100 represents a $100 increase from 2025. The deductible increase of $25 might seem small until you realize that both numbers shift every January, and insurance companies adjust plan premiums accordingly. Beneficiaries who budget based on 2026 costs will find themselves underfunded in 2027, 2028, and beyond. Insurance companies administering Part D are already signaling higher costs ahead.
Per-enrollee annual costs are anticipated to increase by 35% in 2026 compared to 2025—a shock that will be absorbed partially through higher premiums and partially through beneficiaries’ out-of-pocket costs. This isn’t a one-time bump; it reflects underlying trends in drug pricing that show no signs of slowing. A beneficiary spending $1,800 out-of-pocket on drugs in 2026 could realistically spend $2,400 in 2028, not just because drug prices rise but because the cap itself increases. This makes retirement healthcare budgets unpredictable and forces retirees to overestimate their drug costs when planning, effectively reducing their spendable retirement income. Someone who successfully managed Part D costs in 2025 cannot assume the same plan will serve them well in 2026, let alone beyond.
Formulary Restrictions and Reduced Plan Options That Narrow Your Choices
The number of standalone Part D plan options available to beneficiaries has shrunk from 12-16 typical choices to only 8-12 for 2026. This reduction means fewer plans to choose from and, frequently, less negotiating power for beneficiaries with specific medication needs. When a plan drops a drug from its formulary or moves it to a higher cost tier, beneficiaries must either pay out-of-pocket for the non-formulary drug, switch to a different medication, or switch to a different plan entirely. None of these options are painless. Non-formulary drugs force you to pay the full retail price without plan assistance.
A specialty medication that costs $3,000 monthly, when excluded from a formulary, means you’re immediately spending thousands before your plan pays anything. Switching to a different medication might work for common conditions like hypertension or high cholesterol, where alternatives abound, but for conditions like cancer, rheumatoid arthritis, or rare genetic disorders, the formulary becomes your prison. You can’t simply choose the plan with the lowest premium; you must choose based on which plan covers your specific drugs, which requires reviewing formularies individually. A retired teacher taking three maintenance medications discovered that no single plan in her region covered all three at the same cost tier. She had to choose between a $40 monthly premium with one medication costing 50% coinsurance, or a $55 monthly premium with better coverage on that drug but worse coverage on another. She’ll never know if she made the optimal choice, and her answer will change every year when formularies update.
Switching Plans Won’t Erase Your Late Enrollment Penalty
Many beneficiaries believe that if they made a mistake with their initial Part D enrollment, switching to a different plan later will reset their situation. This misunderstanding has cost thousands of retirees millions in cumulative penalties. The late enrollment penalty is tied to your beneficiary status, not to any specific plan.
Changing from one Part D plan to another, moving from a standalone PDP to a Medicare Advantage plan that includes drug coverage (MA-PD), or switching between MA-PD plans does nothing to eliminate the penalty. You will continue paying the surcharge month after month, year after year, for as long as you have Medicare drug coverage. One retired federal employee switched plans five times over a decade, hoping each plan change would be a “fresh start.” His penalty, calculated during his first lapse in enrollment twenty years earlier, followed him through every single plan. He paid the permanent surcharge thousands of times over those decades and only discovered late in his retirement that he could have appealed or requested relief during his initial enrollment period—something he couldn’t do retroactively.
The Enrollment Period Trap and Strategic Planning for the Future
Most beneficiaries understand that missing their initial enrollment period triggers penalties, but far fewer understand the enrollment period windows that apply afterward. If you miss your initial enrollment period, you can only enroll during the annual “Open Enrollment Period,” which runs October 15 through December 7 each year. Missing this window means waiting another year to enroll—another year of accumulating penalties. The 2026 average Part D premium of $34.50 (down nearly 10% from 2025) might seem to suggest lower costs ahead, but this decrease reflects plan competition and subsidies more than actual drug cost reduction.
As the population ages and the number of enrollees continues to grow—56.1 million people were enrolled in Part D as of February 2026—the baseline costs underlying these plans will continue to pressure both premiums and out-of-pocket limits upward. Looking forward, the Medicare landscape will likely continue shifting toward more managed care models and formulary restrictions as plans attempt to manage costs. Beneficiaries who understand Part D’s hidden costs today will be better positioned to plan strategically: choosing plans based on their specific medication needs, understanding IRMAA brackets and planning income accordingly, and enrolling on time to avoid permanent penalties. The complexity of Part D is unlikely to decrease, making informed decision-making not a luxury but a necessity for anyone approaching retirement.
Conclusion
The elimination of the donut hole was marketed as simplification, and in one narrow sense it was. But the Medicare Part D landscape of 2026 contains multiple hidden costs that have replaced the coverage gap: permanent late enrollment penalties, income-related surcharges, formulary restrictions, and annual increases to out-of-pocket limits. These costs are not advertised equally; the government publishes them, but understanding their full impact requires reading multiple documents and connecting dots that aren’t visibly connected. An American who enrolls in Part D without understanding these hidden costs is making one of the most expensive mistakes of their retirement.
Your next step is straightforward but crucial: review your current or projected Part D enrollment against the 2026 structure, verify whether you have creditable coverage that might exempt you from penalties, check your income against IRMAA brackets, and compare not just premiums but formularies for your specific medications. If you’re approaching Medicare age, mark your initial enrollment period calendar today. If you’re already enrolled, use the next Open Enrollment Period to reassess your plan against your current medication needs and income situation. The $34.50 average monthly premium is only the beginning of what you’ll actually spend, and the thousands you might save or lose depend on decisions made now—with full knowledge of what you don’t know.