Medicare · July 29, 2026 · 4 minute read

COBRA is not employer coverage

It is the most expensive misunderstanding in Medicare, and it comes from an assumption that sounds entirely reasonable: I have health insurance, so I am covered, and I will handle Medicare when this runs out.

Here is how it happens. You work past 65, which plenty of people do, and you keep the health plan through your employer. Because you have credible coverage through active employment, you are allowed to delay Part B without penalty. That much is true and well understood.

Then the job ends. Retirement, a layoff, a decision to step back. You are offered COBRA, which lets you continue the same plan for a period at your own expense. You take it. Same insurance card, same doctors, same network. Nothing about the experience feels like a coverage gap.

And that is exactly the problem.

What the rule actually says

The Special Enrollment Period that lets you take Part B without a late penalty runs for eight months, and it starts when your employment ends or your employer coverage ends, whichever comes first.

COBRA does not count as active employer coverage for this purpose. It is a continuation of a plan, not employment. Your eight-month clock started the day the job ended, and it has been running the entire time you have been paying COBRA premiums and feeling covered.

The card in your wallet says you have insurance. Medicare says your window is closing.

COBRA commonly lasts eighteen months. The Special Enrollment Period lasts eight. People discover the gap somewhere around month ten, or worse, when COBRA ends and they go to enroll.

What it costs to get this wrong

If your window has closed, the next opportunity to enroll in Part B is the General Enrollment Period, January 1 through March 31. Coverage from that enrollment does not begin immediately.

There is also a penalty, and this is the part that stings. The Part B late enrollment penalty is 10 percent of the standard premium for each full 12-month period you could have had Part B and did not. It is not a one-time fee. It is added to your premium for as long as you have Part B, which is to say for the rest of your life.

Two years late is a 20 percent surcharge on every monthly premium from then on. At 67, with decades of premiums ahead, that adds up to real money for a paperwork mistake.

Part D has a similar penalty calculated differently, and it applies if you go without creditable prescription coverage. Worth confirming whether your COBRA drug coverage counts as creditable, since not all of it does.

What to do instead

• If you are 65 or older and being offered COBRA, ask about Part B timing before you elect it. One phone call to Social Security, your benefits administrator, or an agent. This is a five-minute question with a permanent answer.
• Write down the date your employment ended. That is the date your clock started, not the date COBRA ends.
• Ask whether the drug coverage is creditable. The plan can tell you, and it decides whether a Part D penalty is also accruing.
• Do not assume that having insurance is the same as having the right insurance. Medicare rules care about the source of the coverage, not the quality of it.

If it already happened

It may still be fixable. Medicare has a process for requesting relief from a late enrollment penalty in cases of misinformation from a federal employee, and certain circumstances can create an additional enrollment opportunity. Neither is guaranteed and both require documentation, but if you are in this position it is worth pursuing rather than accepting.

If you are not in this position yet and COBRA is sitting on the table, take the five minutes. This is the one Medicare mistake we see most often, and it is entirely preventable.