The short answer
If you are 65 or older and keep COBRA instead of enrolling in Medicare, you can trigger a lifelong Part B late-enrollment penalty. The reason is that COBRA is not considered active employer coverage for Medicare purposes — it does not let you delay Part B without penalty. Only coverage from a job where you or your spouse are actively working counts. Once you turn 65, the clock on your Medicare enrollment starts regardless of whether you still hold COBRA.
So COBRA and Medicare do not mix the way people assume, and treating COBRA as a reason to postpone Medicare is a costly error.
Why the penalty happens
When you turn 65, you get a seven-month Initial Enrollment Period for Medicare. If you skip Part B because you have COBRA, you do not get a special enrollment period when COBRA ends, because COBRA is not creditable active-employment coverage. You may then wait months for the next general enrollment window, go uninsured for Part B services, and pay a Part B penalty of 10 percent for each full 12-month period you delayed — for life.
The trap is believing COBRA behaves like the job coverage that legitimately lets people delay Medicare. It does not.
How to avoid it
If you are approaching 65 and on COBRA, enroll in Medicare during your Initial Enrollment Period rather than relying on COBRA. If you delayed Part B because of genuine active-employment coverage that later became COBRA, our guide to the 8-month special enrollment period after employer coverage explains the window that applies. When in doubt, review timing before COBRA starts. Our Medicare overview covers enrollment basics.
The takeaway: at 65, enroll in Medicare on time — COBRA will not protect you from the Part B penalty.
Frequently Asked Questions
Does COBRA count as creditable coverage for Medicare?
No. COBRA is not active-employment coverage, so it does not let you delay Part B without penalty and does not create a special enrollment period when it ends.
What happens if I keep COBRA instead of enrolling in Medicare at 65?
You can incur a lifelong Part B late-enrollment penalty of 10 percent for each full year you delayed, and face a gap until the next enrollment window.
I am 65 and still working with employer coverage — is that different?
Yes. Coverage from a job where you or your spouse actively work can let you delay Part B without penalty. COBRA does not, because no one is actively employed under it.
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