The lifetime surcharge for signing up late for Part B or drug coverage
Updated October 2026
Part B. Count the months between the end of your Initial Enrollment Period and the end of the enrollment period in which you finally signed up, leaving out months covered by a group health plan based on current work. Each full 12 months adds 10% of the standard Part B premium. Partial years do not count: 23 months is still 10%.
Part D. Count each month, after your Initial Enrollment Period, that you went without Part D or other creditable drug coverage for a stretch of 63 days or more. Multiply 1% by the number of months and by the national base beneficiary premium, then round to the nearest 10 cents. Because the base premium is reset each year, the Part D penalty changes every January.
Part B, 24 months late. 24 months is two full 12-month periods: 20%. In 2026, 20% × $202.90 = $40.58, so the premium is $243.48 a month, which Medicare bills as $243.50.
Part D, 14 months without coverage. 14% × $38.99 = $5.4586, rounded to $5.50 a month on top of the plan premium. In 2027 the base premium is $41.33, so the same 14 months becomes 14% × $41.33 = $5.79, rounded to $5.80.
Initial Enrollment Period: seven months, from three months before the month you turn 65 to three months after. General Enrollment Period: January 1 to March 31 each year for Part B (and premium Part A); coverage starts the month after you sign up. Special Enrollment Period: up to 8 months after you or your spouse stop working, or the job-based coverage ends, whichever comes first, if you had group coverage from current work. Part D: your Initial Enrollment Period, then Open Enrollment each October 15 to December 7, or a special period after losing creditable coverage.
Example: a person who turned 65 in June 2022 had an Initial Enrollment Period ending September 2022. Signing up for Part B in the 2026 General Enrollment Period (ending March 31, 2026) counts 42 months: three full 12-month periods, so a 30% penalty, $60.87 a month in 2026.
| Situation | Part | Months | Penalty | Per month (2026) | Per year (2026) |
|---|---|---|---|---|---|
| Turned 65 in June 2022, signs up for Part B in the 2026 General Enrollment Period | Part B | 42 | 30% | $60.87 | $730.44 |
| 11 months late for Part B | Part B | 11 | 0% | $0.00 | $0.00 |
| No Part B for 5 full years | Part B | 60 | 50% | $101.45 | $1217.40 |
| 14 months without drug coverage (Medicare.gov example) | Part D | 14 | 14% | $5.50 (2027: $5.80) | $66.00 |
| 27 months without drug coverage | Part D | 27 | 27% | $10.50 (2027: $11.20) | $126.00 |
| Went without drug coverage for 4 years | Part D | 48 | 48% | $18.70 (2027: $19.80) | $224.40 |
Part B penalties step up only at each full year; Part D penalties grow month by month. Both are paid every month for life in most cases, so a $40 monthly penalty costs about $9,700 over 20 years at today’s premiums, and more as premiums rise.
For Part B, enter the months from the end of your Initial Enrollment Period to the end of the period in which you enrolled, minus any months you had group coverage through your own or your spouse’s current job. For Part D, enter the months without creditable drug coverage after your Initial Enrollment Period (only gaps of 63 days or more count; your plan’s notice of creditable coverage tells you whether past coverage qualified). The Part B premium defaults to the 2026 standard $202.90; CMS usually announces the 2027 premium in November. Choose 2026 or 2027 for the Part D base premium.
Drug coverage is “creditable” if it is expected to pay at least as much as standard Part D; employers and insurers must tell you each year. Health coverage from current employment (yours or a spouse’s) lets you delay Part B without penalty if the employer has 20 or more employees. COBRA and retiree coverage are not coverage based on current employment: the 8-month Special Enrollment Period starts when the job ends, even if you take COBRA, so relying on COBRA past those 8 months is the most common way people end up with a Part B penalty.
People who qualify for Extra Help with drug costs do not pay the Part D penalty, and enrolling in a Medicare Savings Program generally removes the Part B penalty. Part A also has a penalty (10% for twice as many years as you were late) but only for people who must buy Part A. If you think a Part D penalty is wrong, for example because you had creditable coverage, you can ask your plan for a reconsideration within 60 days of the notice.
It does not decide which months count for you; that depends on your work history, the size of the employer and your notices of creditable coverage. It does not include IRMAA income surcharges (see the IRMAA calculator), the Part A penalty, or the plan’s own Part D premium. Penalties are figured on the standard Part B premium and the national base Part D premium, not on what your plan charges. Social Security (for Part B) and your drug plan (for Part D) send the official figure; a State Health Insurance Assistance Program (SHIP) counselor can help check it free of charge.
Assuming COBRA protects you. It does not for Part B. Waiting past the 8-month window after a job ends. Small-employer coverage. With fewer than 20 employees, Medicare is usually primary and you may need Part B at 65. Dropping drug coverage because you take no drugs. The Part D penalty counts months without coverage, not prescriptions. Ignoring the creditable-coverage notice from a retiree or marketplace plan.