Medicare’s Part D penalty punishes a gap, not a decision. Going 63 days or more without prescription-drug coverage after becoming eligible is enough to trigger it, whether or not the person ever meant to skip Part D. The penalty itself runs 1% of a national benchmark premium for every month of that gap, which adds up to 12% for a full year missed, and unlike some Medicare costs, it keeps applying for as long as the person carries Part D at all.
1% A Month, 12% A Year: Of What?
Medicare charges “an extra 1% for each month” someone goes without creditable drug coverage, which the agency notes “is 12% a year,” according to Medicare’s guidance on avoiding late enrollment penalties. That percentage applies to the national base beneficiary premium, which the Centers for Medicare & Medicaid Services set at $38.99 for 2026, per CMS’s 2026 Part D bid-information fact sheet. Medicare rounds the result “to the nearest $.10” before adding it to the monthly bill, according to the agency’s Part D late-enrollment-penalty page. Calculated directly from the 12%-a-year rate and the $38.99 base premium, then rounded the way Medicare describes, a full 12-month gap in coverage adds roughly $4.70 a month to whatever drug plan premium the person eventually pays, a number this article computes from Medicare’s own rate, premium and rounding rule, not a dollar figure Medicare publishes directly.
One group is exempt regardless of how long the gap ran. “If you get Extra Help, you don’t pay a late enrollment penalty,” the same Medicare page states. That means a beneficiary who qualifies for the low-income subsidy that helps cover Part D costs does not carry this surcharge even after a coverage gap that would otherwise trigger it.
The gap Medicare’s rule doesn’t fill: Medicare’s 63-day rule tells someone when a penalty applies, but not how the new Part D out-of-pocket cap changes what a monthly drug bill looks like once they’re actually enrolled. See the 2026 cap in The Medicare Cost & Coverage Protection Kit.
The 63-Day Trigger, And What Actually Counts As Creditable
The penalty doesn’t depend on having zero drug coverage forever. It depends on a specific gap. “If you go 63 days or more in a row without Medicare drug coverage OR other creditable prescription drug coverage after you were eligible for Medicare, you may have to pay a lifetime Part D late enrollment penalty if you sign up for Medicare drug coverage later,” Medicare states on its creditable-coverage page. “Creditable” has a specific meaning too: coverage that’s “expected to pay, on average, at least as much as Medicare drug coverage,” which Medicare says can include coverage through a current employer or union, TRICARE, the Indian Health Service, or the VA. Someone who assumes any drug coverage at all protects them from the penalty can still end up owing it if that coverage doesn’t clear this bar.
Why It Rides Along For As Long As You Have Part D
Once the penalty attaches, it doesn’t fade with time the way some fees do. “This monthly penalty is added for as long as you have Medicare drug coverage, even if you switch plans,” according to the same Medicare avoid-penalties guidance. Switching from one Part D plan to another does not restart the clock or erase the surcharge. The extra 1% per uncovered month keeps applying to the new plan’s premium exactly as it did to the old one, for however many years the person continues carrying Medicare drug coverage.
The Stabilization Cap Behind The 2026 Premium
The $38.99 base the penalty is measured against isn’t rising freely. CMS’s 2026 fact sheet notes the base beneficiary premium is “subject to the Inflation Reduction Act’s premium stabilization provision, which caps annual increases at 6% or less through 2029,” per the same CMS fact sheet. That cap limits how fast the benchmark premium, and therefore the dollar value of each 1% penalty increment, can grow year to year, even as the underlying percentage owed by someone with a coverage gap stays fixed under Medicare’s rule. The $38.99 figure is also only a starting point rather than what most people actually pay: CMS uses it as the base for calculating each individual plan’s own premium, so a penalty calculated against the national number can land differently than 1% of the premium shown on any one plan’s bill.
Checking Whether A Coverage Gap Counts As Creditable
Knowing the 63-day rule is one thing; confirming whether a specific past plan actually met Medicare’s “creditable” bar is another, since that label depends on how a former plan’s benefits compared with Medicare drug coverage, not simply on whether the person had some kind of coverage at the time.
The Medicare Cost & Coverage Protection Kit pairs a medication and cost tracker with an appeal and call log for keeping a plan-by-plan coverage record.
Compare drug costs in The Medicare Cost & Coverage Protection Kit.
This article was produced with AI assistance and checked against the primary sources linked above.
David M. Keller is a finance writer based in Columbus, Ohio, covering personal finance and consumer-focused economic topics. He earned his degree in journalism from Ohio University and began his career reporting on local business and economic trends for a regional media outlet. Since then, he has contributed to a variety of online publications, focusing on clear, practical coverage of topics such as cost of living, debt, and everyday financial decision-making.
