Late Enrollment Penalty Calculator
If you delayed signing up for Medicare Part B or Part D without other qualifying coverage, you may owe a permanent monthly penalty. Find out exactly what it costs.
Count only months when you didn't have Medicare or other "creditable" coverage (like employer insurance).
How the penalties actually work
Part B penalty
If you don't enroll in Part B when you're first eligible (and don't have other qualifying coverage), Medicare charges you a permanent 10% premium increase for every 12-month period you went without coverage. The penalty is added to your Part B premium for as long as you have Medicare. It is not a one-time charge — it is forever.
Example: if you delayed Part B by 36 months, your premium will be 30% higher than the standard rate, every month, for life.
Part D penalty
Part D is calculated differently. The penalty is 1% of the "national base beneficiary premium" (about $37 in 2026) per month you went without coverage. So 24 months without Part D = a 24% penalty, applied to ~$37 = about $9 extra per month, every month, for life.
What counts as "creditable coverage"
You won't owe a late penalty if you had other coverage that Medicare considers as good as Medicare's own — typically employer or union group health insurance with prescription drug coverage. Your prior plan should send you a "creditable coverage" notice each year. Keep these letters.
The good news (and the catch)
If you've never been late, this tool will show $0 penalty. Excellent. The catch: penalties stop growing only once you actually enroll. If you're considering delaying enrollment, the math almost never works in your favor unless you have genuinely creditable coverage.