Medicare set the 2026 national base beneficiary premium at $38.99, a number most people never notice unless they enrolled in a Part D drug plan late. That figure is the multiplier behind the Part D late-enrollment penalty, a surcharge calculated as 1% of the base premium for every full month a person went without Part D or other creditable drug coverage after first becoming eligible. Unlike a one-time fee, the penalty is added to a beneficiary’s premium for as long as they carry Part D coverage — for the rest of their life, on top of whatever plan they choose.
How the $38.99 Premium Becomes a Lifetime Penalty
Medicare’s cost publication for 2026 sets the national base beneficiary premium at $38.99, a figure CMS recalculates every year from the average bid submitted by Part D plans nationwide rather than from any single plan’s own price. The base premium isn’t what most enrollees actually pay each month, since plan premiums vary widely by insurer and coverage tier; its real function is as the fixed unit CMS uses to price the late-enrollment penalty for anyone who delayed signing up.
The penalty itself is calculated by multiplying 1% of that base premium by the number of full, uncovered months a person went without Part D or equivalent creditable coverage after their initial enrollment period ended, according to Medicare’s fact sheet on the Part D late-enrollment penalty. A person who waited 14 months past eligibility, for example, faces a 14% penalty — 14% of $38.99, rounded to the nearest ten cents, added to whatever premium their chosen plan already charges.
The base beneficiary premium has risen most years since Part D began in 2006, tracking growth in Part D plan bids nationally rather than any inflation index tied to Social Security’s own COLA. In 2025 the figure stood lower than $38.99, meaning anyone already carrying a late-enrollment penalty saw their surcharge amount increase for 2026 even without any change in their own enrollment history — the percentage stayed the same, but the number it’s multiplied against went up.
Free retirement updates: One number can cost or save hundreds a month in retirement. The free Retirement Shield newsletter surfaces the ones worth knowing. Sign up free.
Why the Penalty Never Expires
Unlike a late fee on a bill, the Part D penalty doesn’t get paid off or phase out. It’s recalculated each year using that year’s national base beneficiary premium, so the dollar amount changes annually even though the percentage assigned for the months of delay stays fixed. A person who accumulated a 20% penalty in an earlier enrollment gap will still pay 20% of $38.99 — about $7.80 a month — added to their 2026 premium, and 20% of whatever the base premium becomes in every subsequent year they keep Part D coverage.
The penalty follows a person even if they switch plans, drop coverage and re-enroll years later, or move to a different state with different plan options. Medicare treats the penalty as attached to the individual’s enrollment history rather than to any particular plan, so shopping for a cheaper premium during open enrollment doesn’t erase it — the percentage carries over and is applied to whatever base premium and plan premium apply in the new plan year.
Consider a person who turned 65 in 2015 but didn’t enroll in Part D or keep creditable coverage until signing up in 2020 — five years, or 60 months, after their initial enrollment period closed. That 60% penalty, once calculated, doesn’t reset to a smaller number if the person later qualifies for Extra Help or switches to a lower-premium plan; it’s applied on top of the 2026 base premium, and on top of every future year’s base premium, for as long as Part D coverage continues, absent a successful appeal.
How to Avoid Owing the Penalty at All
The penalty only applies to people who lacked creditable prescription drug coverage — coverage Medicare considers at least as good as a standard Part D plan — for 63 or more consecutive days after their initial enrollment period. Someone who kept employer, union, or VA drug coverage that met that standard, and can document it, owes nothing extra when they eventually enroll in Part D, according to Medicare’s guidance on avoiding late-enrollment penalties. The burden of proving that coverage was creditable falls on the beneficiary, not the prior plan or employer.
A beneficiary who believes the penalty was calculated in error, or who can locate proof of creditable coverage after the fact, can request a reconsideration through their Part D plan, which forwards the case to an independent review entity under contract with CMS. Successful appeals do happen, but they require documentation — a certificate of creditable coverage, an employer letter, or plan records — that a retiree may not think to keep for years after leaving a job, long before the penalty ever becomes relevant.
That documentation requirement is where the penalty most often catches people off guard: a retiree who assumes a former employer’s drug benefit was automatically creditable, without ever receiving or keeping the notice confirming it, can find themselves owing a permanent surcharge years after the gap in coverage occurred. Because the $38.99 base figure moves every year and the percentage is locked in for life, the cost of a coverage gap made in 2026 will keep compounding on whatever base premium CMS sets a decade from now — a detail that rarely surfaces until the bill arrives.
This article was drafted with AI assistance and edited for accuracy.
More Financial Reading
