If you enrolled in Medicare 18 months after your Initial Enrollment Period ended, here is what your 2026 Part B and Part D penalties come to — and what they'll cost over a lifetime.
Quick answer: At 18 months late, your 2026 Medicare late-enrollment penalty is about $27.29/mo — $20.29/mo for Part B and $7.00/mo for Part D — added to your premiums for as long as you keep the coverage (roughly $6,550 over a 20-year retirement). The penalty is permanent; enrolling during your Initial Enrollment Period or a valid Special Enrollment Period is the only way to avoid it.
At 18 months late, your 2026 Medicare late-enrollment penalties add up to a combined $27.29/month surcharge on top of your regular premiums — $327/year, and roughly $6,550 over 20 years. Both penalties are permanent: Part B adds 10% to your standard premium forever, and Part D adds $7.00/mo to your drug plan. Here is exactly how each one is calculated.
At 18 months late, you've completed 1 full 12-month period (the last 6 months are a partial period and don't add another penalty tier yet). Your Part B penalty is 10% of the standard premium: 10% × $202.90 = $20.29/month, added permanently. The next tier (20%) kicks in at month 24 — you're 6 months away from it.
The Part D penalty is 1% of the national base beneficiary premium per uncovered month, rounded to the nearest $0.10. At 18 months: 1% × $38.99 × 18 = $7.02 → rounded to $7.00/month. This $7.00/mo is added to your drug-plan premium for life and recalculates each January as CMS adjusts the national base (the percentage stays fixed; only the dollar amount shifts).
Both penalties last as long as you have the coverage. At $27.29/mo combined, that's $327/year in extra premiums. Over 20 years of retirement (a common planning horizon), the penalties accumulate to roughly $6,550 — before accounting for the annual Part D base adjustment or future premium changes. The only way to stop paying is to disenroll from Part B or Part D, which creates its own gaps and risks. For most people, the penalties are simply a permanent part of their Medicare cost.
Enter your specific months for Part B and Part D separately — they can differ if you had employer drug coverage after missing Part B enrollment.
Open the 2026 Penalty Calculator →Yes. Both the Part B and Part D late-enrollment penalties are added to your premium for as long as you have that coverage — they do not expire. The Part D penalty recalculates each January as CMS updates the national base beneficiary premium, so the dollar amount can change, but the percentage you owe (based on your months late) stays fixed.
Very rarely. Part B penalties can sometimes be waived if you can prove you received incorrect information from an official government source that caused you to delay enrollment. You'd file a reconsideration with SSA. Part D penalties can be waived if you had creditable drug coverage (employer plan, VA, TRICARE, etc.) for the months in question and can provide a letter proving it. Routine mistake, not-knowing, or insurance-company delays are generally not accepted as grounds for waiver.
They often are. Part B counts the months you were eligible for Medicare Part B but didn't have it. Part D counts the months you went without any creditable prescription drug coverage (employer drug plans, VA, TRICARE, etc. often count). The penalty calculator lets you enter each separately.
The percentage stays fixed at 18% of the base — 18 × 1% — but the dollar amount can inch up each year because CMS adjusts the national base beneficiary premium annually. Your penalty will never get lower than $7.00/mo in today's terms unless coverage rules change.
Showing a prospect a real lifetime-cost number — $6,550 over 20 years — is one of the fastest closes for getting a hesitant T65 off the fence. The Late Enrollment Penalty Calculator on this page is free to share with clients. The Turning 65 Medicare Enrollment Kit gives them a printable checklist + worksheet so they never miss their window.
See Medicare agent tools on Etsy →2026 penalty figures are verified against U.S. government primary sources: