Find out exactly what the Medicare Part B late enrollment penalty costs you — a permanent 10% added to your premium for every full 12-month period you delayed without creditable coverage. Enter your enrollment gap to see the monthly penalty, your total premium with IRMAA, and the lifetime cost.
Situation: You turned 65 but did not enroll in Part B for 24 months, and you had no employer coverage. The 2026 standard premium is $202.90.
Penalty: 2 full 12-month periods × 10% = 20%.
Calculation: 20% × $202.90 = $40.58 per month, added permanently.
Situation: You worked past 65 and were covered by an active employer health plan with 50 employees. You enroll in Part B three months after retiring at 68.
Rule: Active employer coverage from an employer with 20+ employees is creditable — no penalty applies.
Action: you qualify for a Special Enrollment Period and should submit the employer's coverage certification with your application.
Situation: After retiring at 66 you took COBRA for 18 months and then enrolled in Part B.
Rule: COBRA and retiree coverage are NOT creditable. The 18-month delay produces a 10% permanent penalty.
Calculation: 10% × $202.90 = $20.29 per month for as long as you have Part B.
Situation: You went 30 months without creditable drug coverage. The 2026 national base beneficiary premium is $36.78.
Part D penalty: 1% per uncovered month × 30 months = 30%.
Calculation: 30% × $36.78 = $11.03 per month, rounded to the nearest $0.10.
Medicare Part B is voluntary, but it is heavily subsidized — the government pays roughly 75% of the program's cost and beneficiaries pay about 25% through premiums. If people could enroll only after they became sick, the risk pool would collapse and premiums would spike for everyone. The late enrollment penalty is therefore designed as a permanent disincentive: it does not go away after a few years and it does not expire when you turn a certain age. You pay it for as long as you have Part B.
| Item | 2026 Amount | Notes |
|---|---|---|
| Standard Part B monthly premium | $202.90 | Paid by most beneficiaries |
| Part B annual deductible | $283 | Before Medicare pays its share |
| Part B late enrollment penalty | +10% per 12-month period | Permanent, based on the standard premium |
| Part D late enrollment penalty | 1% per uncovered month | × the national base beneficiary premium ($36.78 in 2026) |
| Initial Enrollment Period | 7 months | The 3 months before, the month of, and 3 months after your 65th birthday |
| General Enrollment Period | Jan 1 – Mar 31 | Coverage begins the month after you sign up |
Critical detail: the penalty is calculated on the standard premium, not on what you actually pay. If IRMAA raises your premium to $689.90, your 20% penalty is still 20% of $202.90 = $40.58 — not 20% of the higher figure. IRMAA and the penalty are calculated independently and then added together.
| Your situation at 65 | Creditable? | Penalty risk |
|---|---|---|
| Active employer coverage, employer has 20+ employees | ✅ Yes | None — Special Enrollment Period available |
| Active employer coverage, employer has fewer than 20 employees | ❌ No | Yes — Medicare is primary, enroll at 65 |
| COBRA continuation coverage | ❌ No | Yes — a very common and expensive mistake |
| Retiree health plan from a former employer | ❌ Usually no | Yes, unless the plan certifies creditable coverage |
| VA health benefits | ❌ No | Yes — VA coverage is not creditable for Part B |
| TRICARE (active duty) | ✅ Yes | None while covered |
| Marketplace (ACA) plan | ❌ No | Yes — and premium tax credits end at 65 |
If you have creditable coverage, you get an 8-month Special Enrollment Period after that coverage ends (or after employment ends, whichever comes first) to sign up for Part B without a penalty.
The penalty is 10% of the standard Part B premium for each full 12-month period you were eligible but did not enroll and had no creditable coverage. With the 2026 standard premium of $202.90, each 12-month period adds $20.29 to your monthly premium permanently.
No. The Part B late enrollment penalty is permanent and is added to your premium for as long as you are enrolled in Part B. It does not expire, and it is not forgiven when you reach a certain age or enroll in a Medicare Advantage plan.
No. COBRA continuation coverage and most retiree health plans are not creditable coverage for Part B purposes. If you rely on COBRA past 65 and then enroll in Medicare, you will owe a permanent late enrollment penalty.
The Part D penalty is 1% of the national base beneficiary premium ($36.78 in 2026) for each month you went without creditable prescription drug coverage. Like the Part B penalty, it is permanent and added to your monthly drug plan premium.
No. The late enrollment penalty is always calculated on the standard Part B premium. IRMAA is determined separately using your modified adjusted gross income from two years prior, and the two amounts are then added together.
Yes. If you believe you had creditable coverage during the period in question, you can request a reconsideration using Form SSA-561 or the appeal instructions on your penalty notice. Providing employer certification or other proof of coverage often results in the penalty being removed.
⚠️ Important Disclaimer: This calculator provides an educational estimate of Medicare late enrollment penalties using 2026 national figures. Penalty determinations are made by the Social Security Administration and Medicare based on your specific enrollment history and coverage documentation. IRMAA tiers and premium amounts are adjusted annually and depend on your tax filing status and modified adjusted gross income from two years prior. Consult Medicare, Social Security, or a SHIP counselor for a determination on your own case.