Medicare Part D Late Enrollment Penalty Calculator
Use this calculator to see how a Medicare Part D late enrollment penalty compounds over time. Enter the number of uncovered months and your expected years on Part D to size the monthly surcharge, the lifetime cost, and how premium inflation changes the bill as you age.
Informational estimate only. Confirm premium projections and penalty calculations with Medicare or your Part D plan.
Examples
- 11 uncovered months, 8 years on Part D, defaults for premium and growth ⇒ Penalty percentage applied to base premium: 11.00% • First-year monthly surcharge: $3.80 • Lifetime penalty over 8.0 years: $379.80 • Monthly penalty in final year: $4.38
- 24 uncovered months, 12.5 years on Part D, $36.50 base, 3% growth ⇒ Penalty percentage applied to base premium: 24.00% • First-year monthly surcharge: $8.80 • Lifetime penalty over 12.5 years: $1,449.37 • Monthly penalty in final year: $11.78
FAQ
How do I know if my prior coverage was creditable?
Plans must send an annual creditable coverage notice. If you kept employer, union, VA, or other coverage that was deemed creditable, exclude those months from the uncovered total.
Do partial months count?
Only full months without creditable coverage count toward the penalty. If your gap started mid-month, round down to whole months unless the gap spanned the entire month.
Can the penalty be forgiven?
Generally no. The only way to avoid it is to qualify for programs like Extra Help (Low-Income Subsidy) or to prove you had creditable coverage. Otherwise the penalty attaches permanently.
What if premiums decrease in a future year?
Set the annual growth input to zero or a negative value to model a temporary reduction. The surcharge will shrink in tandem because it is recalculated on the updated base premium.
Additional Information
- Medicare multiplies the national base beneficiary premium by 1% for each full uncovered month and rounds the result to the nearest $0.10.
- The surcharge never expires—you pay it as long as you keep Part D, even if you later enroll in a low-premium plan.
- Premiums typically change each year. The calculator inflates the base premium before reapplying the penalty so you can budget for higher late fees down the road.