Both penalties are permanent and both are avoidable. Part B: 10% of the standard premium ($202.90 in 2026) for every full 12 months you could have had Part B but did not, unless you had coverage from a current employer. Part D: 1% of the national base premium ($38.99) for every month without Part D or other creditable drug coverage after your Initial Enrollment Period, rounded to the nearest 10 cents.
The Part B penalty
Example: you were first eligible in June 2023 but did not enroll until the General Enrollment Period in February 2026, with no employer coverage. That is 32 months, or two full 12-month periods, so your penalty is 20% of $202.90: $40.58 a month, for as long as you have Part B, and it grows every year as the premium rises.
| Full years late | 2026 monthly penalty | 2026 Part B premium with penalty |
|---|---|---|
| 1 | $20.29 | $223.19 |
| 2 | $40.58 | $243.48 |
| 3 | $60.87 | $263.77 |
| 5 | $101.45 | $304.35 |
Who is exempt: anyone covered by a group health plan from their own or their spouse’s current employment (20 or more employees). You get an eight-month Special Enrollment Period after the job or the coverage ends. COBRA, retiree plans and individual Marketplace plans do not count.
The Part D penalty
Example: your Initial Enrollment Period ended in September 2024 and you joined a Part D plan in January 2026, 15 months later, with no creditable coverage in between. The penalty is 15% of $38.99, which is $5.85, rounded to $5.90 a month, added to your plan premium every year for as long as you have Part D (recalculated as the base premium changes).
| Months without creditable coverage | 2026 monthly penalty |
|---|---|
| 6 | $2.30 |
| 12 | $4.70 |
| 24 | $9.40 |
| 60 | $23.40 |
Creditable coverage is drug coverage at least as good as Medicare’s: most employer plans, VA benefits, TRICARE and the Indian Health Service. A gap of 63 days or less does not count. People who qualify for Extra Help do not pay the Part D penalty.
How to avoid both
- Enroll in Part B during your Initial Enrollment Period unless you have active employer coverage.
- Keep some creditable drug coverage from the day your Part D window closes, even a low-premium plan if you take no medications.
- Run the Part B and Part D penalty calculators before deciding to wait.