If your Medicare Part D plan or CMS sent a notice showing a late-enrollment penalty near $40 a month, here is exactly how that number is built, what it costs over a lifetime, and how to check whether it's wrong.
Quick answer: A Part D late-enrollment penalty of about $40/month means CMS counted roughly 103 months (about 8.6 years) without creditable drug coverage. The exact 2026 formula for 103 months is $40.20/mo — that's 103% of the $38.99 national base premium. It's added to your drug-plan premium for as long as you have Part D (roughly $9,648 over a 20-year retirement). If you actually had creditable coverage during those months, the penalty may be wrong and can be appealed.
A Part D late-enrollment penalty of about $40/month corresponds to roughly 103 months — about 8.6 years — that you went without creditable prescription drug coverage after your Initial Enrollment Period closed. CMS turns that month count into a penalty using one fixed rule, and the result (40.2/mo for 103 months in 2026) is then added to your drug-plan premium for as long as you stay on Part D — about $482/year, or roughly $9,648 across a 20-year retirement.
CMS multiplies 1% of the national base beneficiary premium ($38.99 for 2026) by the number of full months you went without creditable coverage, then rounds to the nearest $0.10. At 103 months: 1% × $38.99 × 103 = $40.16 → rounded to $40.20/month. That is the same as saying you owe 103% of the base premium. Because your searched amount ($40) is a round number and the real penalty tracks your exact month count, your plan's notice may read a few cents above or below $40.20 — the formula, not the rounding, is what matters.
A Part D penalty is only correct if you genuinely lacked creditable drug coverage for those ~103 months. Many penalties are wrong because the beneficiary did have qualifying coverage that was never reported. Coverage that usually counts as creditable: an employer or union drug plan, VA or TRICARE benefits, or another Medicare drug plan. If you had any of these during the months CMS counted, request a letter of creditable coverage from that plan and submit it with the reconsideration form that came with your penalty notice — you generally have 60 days from the date of the notice to file. If you qualify for Extra Help (the Low-Income Subsidy), the Part D late-enrollment penalty is removed entirely. Don't assume the number is final until you've checked your coverage history.
Enter your own months without creditable drug coverage to see the precise 2026 figure — and your Part B penalty too, if you delayed that as well.
Open the 2026 Penalty Calculator →The Part D penalty is not a one-time charge or a temporary catch-up fee. At $40.20/mo it is added to your drug-plan premium every month for as long as you have Part D — $482/year, and roughly $9,648 over 20 years before any annual base adjustment. The percentage (103%) is locked in; only the dollar figure drifts as CMS updates the national base each January. The penalty ends only through a successful appeal (creditable coverage) or by qualifying for Extra Help.
Because CMS calculates the penalty as 1% of the national base beneficiary premium ($38.99 in 2026) for every full month you went without creditable prescription drug coverage after your Initial Enrollment Period ended. A penalty near $40/month works out to roughly 103 months — about 8.6 years — uncovered. The exact 2026 amount for 103 months is $40.20/mo.
Sometimes — and it's worth checking. The Part D penalty can be removed if you can prove you actually had creditable drug coverage during the ~103 months CMS counted: ask that prior plan for a letter of creditable coverage and file the reconsideration request that accompanied your notice (usually within 60 days). It is also eliminated automatically if you qualify for Extra Help / the Low-Income Subsidy. What generally won't work is simply not knowing about the rule or saying the premium is unaffordable.
The percentage stays fixed at 103% of the base, but the dollar amount can change every January because CMS adjusts the national base beneficiary premium annually. If the base rises, your $40.20/mo will rise proportionally; if it falls, yours falls too. The percentage never changes once it's set.
No. It is not a one-time fee or a temporary surcharge — it is added to your drug-plan premium for as long as you have Part D coverage. The only ways it stops are a successful appeal (if you had creditable coverage), or qualifying for Extra Help / the Low-Income Subsidy, which eliminates the Part D late-enrollment penalty entirely.
Clients who see a real, permanent $40.20/month penalty — about $9,648 over 20 years — finally understand why enrolling on time matters. The free calculator on this page is yours to share. The Turning 65 Medicare Enrollment Kit gives prospects a printable checklist so they never trigger a penalty in the first place.
See Medicare agent tools on Etsy →2026 Part D penalty figures are verified against U.S. government primary sources: