How much is the Medicare Part D late enrollment penalty?
The Part D late enrollment penalty is 1% of the national base beneficiary premium ($38.99 in 2026) multiplied by the number of full months you went without Part D or other creditable drug coverage, rounded to the nearest ten cents. It is added to your plan premium every month, permanently.
Last reviewed August 17, 2026 · Published August 17, 2026 · Mere Benefits Data Desk
The penalty only applies if you went 63 or more days in a row without creditable drug coverage after your Initial Enrollment Period ended. Creditable coverage means drug coverage at least as good as standard Part D, and it includes employer plans that certify as creditable, VA drug coverage, and TRICARE. If you had any of those the whole time, you owe nothing, no matter how late you join a Part D plan.
The 2026 math
The penalty is 1% of the national base beneficiary premium for each full month you were without creditable coverage. For 2026 the base premium is $38.99, so each month of gap costs about $0.39 per month, every month, for as long as you have Medicare drug coverage.
| Months without creditable coverage | Penalty percentage | 2026 monthly penalty |
|---|---|---|
| 10 months | 10% | $3.90 |
| 20 months | 20% | $7.80 |
| 36 months | 36% | $14.00 |
| 60 months | 60% | $23.40 |
Amounts are 1% times $38.99 times the months, rounded to the nearest ten cents, then added on top of whatever your plan’s own premium is.
A worked example
Example: your Initial Enrollment Period ended May 2023 and you enrolled in a drug plan effective January 2026 with no creditable coverage in between. That is 31 full months. The math for 2026: 31 × 1% × $38.99 = $12.09, which rounds to $12.10 added to your plan premium each month.
Two things make this penalty sneaky. First, it is permanent. Second, it is recalculated every year using that year’s national base beneficiary premium, so the dollar amount can change annually even though your penalty percentage is fixed.
How people avoid it
You may avoid the penalty by enrolling in a Part D or Medicare Advantage drug plan when you are first eligible, even a low-premium plan you barely use, or by keeping proof of creditable coverage from an employer, the VA, or TRICARE. If you receive Extra Help (the Low-Income Subsidy), you do not pay a late enrollment penalty at all.
Here’s what I tell clients who feel healthy and skip drug coverage at 65: the penalty math almost always costs more over a retirement than the cheapest drug plan would have. Keep the paperwork showing creditable coverage, because if a plan later bills you a penalty, that notice is your appeal evidence.
Sources
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