Health & Medicare
Medicare Part B Late Enrollment Penalty Explained
Standard premium sourced directly from CMS via the Federal Register; penalty formula cross-confirmed via Healthline.
A one-time delay creates a penalty that follows you permanently, growing every year the standard premium itself rises. Here is exactly how the math works.
Data sourced from CMS (Federal Register), Healthline
The formula: 10% per full 12-month period, no rounding up
The penalty adds 10% to your Part B premium for every full 12-month period you were eligible for Part B but did not enroll, and did not have other qualifying coverage.
The "full" part matters: partial years never round up, a 14-month delay counts as exactly one full 12-month period, not two, since only one complete 12-month period has actually elapsed.
To calculate your own exact penalty based on your specific delay, the Medicare Part B late enrollment penalty calculator runs the full-period counting rule directly against your number of months.
The fact that surprises people most: it is permanent
This is not a one-time fee assessed once and forgotten, the Part B penalty is added to your premium for as long as you carry Medicare Part B, potentially for the rest of your life.
It is also recalculated every year against whatever the current standard Part B premium happens to be, so the actual dollar amount of the penalty grows over time even though the percentage itself never changes.
At the 2026 standard premium of $202.9, a single 12-month penalty period adds about $20.29 a month right now, and that dollar figure will climb in future years as the base premium itself rises.
The exception that matters: employer coverage
Not everyone who delays Part B gets penalized. Someone still actively covered by a current employer's group health plan, their own or a spouse's, provided the employer has enough employees to qualify, generally avoids the penalty for delaying Part B during that period of employer coverage.
The penalty specifically targets delaying without any qualifying alternative in place, not delaying itself. Confirm your specific employer plan actually qualifies before assuming this exception automatically applies to your situation.
Frequently asked questions
How is the Medicare Part B late enrollment penalty calculated?
You add 10% to your Part B premium for every full 12-month period you were eligible for Part B but did not enroll and did not have other qualifying coverage. Partial years do not round up, a 14-month delay counts as just one full 12-month period, not two.
Is this penalty temporary, like a one-time fee?
No, and this is the single most important fact about it. The Part B penalty is permanent, added to your premium for as long as you have Medicare Part B, potentially for the rest of your life.
It is recalculated against whatever the current standard Part B premium is each year, so the dollar amount grows over time even though the percentage penalty itself stays fixed.
What does a 14-month delay actually cost, in dollars?
At the 2026 standard Part B premium of $202.9, a single 12-month penalty period adds about $20.29 a month, for life, recalculated each year against the new standard premium. That is the cost of just one 12-month period, a longer delay stacks additional 12-month periods on top.
Does everyone who delays Medicare Part B get penalized?
No, only people who delay without other qualifying coverage. Someone still covered by a current employer's group health plan (their own or a spouse's, if the employer has enough employees to qualify) generally is not penalized for delaying Part B during that coverage, since the employer plan counts as an acceptable substitute. The penalty specifically targets delaying without any qualifying alternative.