Employer coverage vs Medicare at 65
Written by My65 Playbook Editorial Team
Last reviewed
If you are still working when you turn 65, you are not automatically required to drop what you have. But "I have insurance through work" is not by itself the answer to whether you can safely wait. The rules turn on how many people your employer has, and a few widely believed shortcuts — COBRA counts, retiree coverage counts, I can keep funding my HSA — are the ones that create permanent, avoidable costs.
How to think about this
Ask three questions in order. First, how many employees does the company have? That single fact determines whether Medicare or your group plan pays first, and it is the hinge everything else swings on. Second, is the coverage you have actually active employment coverage, not COBRA or a retiree plan? Only active coverage protects your right to enroll later without penalty. Third, are you contributing to a health savings account? If so, starting any part of Medicare changes what you are allowed to do. Answer those three and the decision usually makes itself.
At a glance
| What changes | Staying on employer coverage | Enrolling in Medicare at 65 |
|---|---|---|
| Employers with 20 or more employees | Your group plan generally pays first and Medicare second. Delaying Part B is usually safe while you are actively working. | You may still enroll, but Medicare would pay second, so you could be paying a premium for coverage that rarely pays first. |
| Employers with fewer than 20 employees | Medicare generally pays first. Staying without it can leave you exposed, because your group plan may pay as though you already had Medicare. | Usually the safer choice. Enrolling on time keeps the primary payer in place. |
| Part A on its own | Many people take premium-free Part A and keep their group plan. It is only a problem if you fund an HSA. | Part A alone is not full coverage. It handles inpatient care, not the doctor visits most people use. |
| Health savings account contributions | You can keep contributing while you have no part of Medicare in force. | Contributions must stop once any part of Medicare begins, and Part A can start retroactively. |
| Enrolling later without a penalty | Active employment coverage gives you a special enrollment period when it ends. | No special period is needed — you are enrolling during your initial window. |
| Prescription coverage | Fine, as long as your employer plan counts as creditable drug coverage. Ask the benefits administrator in writing. | You would add Part D or a plan that includes drug coverage when you enroll. |
Staying on employer coverage
- Your employer has 20 or more employees and you are actively working there.
- Your group plan is genuinely good and you have confirmed in writing that its drug coverage is creditable.
- You are still contributing to a health savings account and want to keep doing so.
- Your spouse and dependents rely on that plan and moving them would be disruptive or costly.
Enrolling in Medicare at 65
- Your employer has fewer than 20 employees, so Medicare would be the primary payer anyway.
- You are retiring, reducing hours, or your active coverage is ending within the next few months.
- Your share of the group premium is high relative to what Medicare would cost you.
- Your coverage is COBRA or a retiree plan rather than active employment coverage.
Watch out for
- COBRA is not active employment coverage. This is the single most expensive misunderstanding on this page. COBRA continues your benefits, but for Medicare's purposes the employment ended — so it does not give you a special enrollment period, and time spent on it can count against you. If you are offered COBRA at or after 65, work out your Medicare timing before you accept it, not after.
- Retiree coverage sits in the same trap. Like COBRA, it is not active employment coverage, and it does not protect a delayed Part B enrollment.
- If you contribute to a health savings account, Part A can create a tax problem you did not see coming. Contributions have to stop before Medicare begins, and when you claim Social Security after 65 Part A can be backdated by several months — which can make contributions you already made excess ones. Plan the stop date deliberately.
- The Part B late-enrollment penalty is permanent, not a one-time fee. It is a surcharge added to your premium that grows with each full year you could have enrolled and did not, and once it attaches you keep paying it. That is precisely why the employer-size question matters more than it looks.
- Get the creditable-coverage answer in writing. A benefits administrator saying "you're fine" on the phone is not evidence you can use later if a drug-coverage penalty is assessed.
Common questions
- Do I have to enroll in Medicare at 65 if I am still working?
- Not necessarily. If your employer has 20 or more employees and you are actively working, you can generally delay Part B without penalty and pick it up when that coverage ends. If the employer has fewer than 20 employees, Medicare usually becomes the primary payer and delaying can leave you underinsured.
- Should I take Part A if it is premium-free?
- Often yes, and many people do. The one clear exception is if you contribute to a health savings account, because those contributions have to stop once Part A begins. If the HSA matters to you, that changes the answer.
- Does COBRA let me delay Part B safely?
- No, and this catches people every year. COBRA is not active employment coverage, so it does not create the special enrollment period that protects a delayed enrollment. If you are approaching or past 65 and considering COBRA, sort out your Medicare timing first.
- How long do I have to enroll after my employer coverage ends?
- There is a limited special enrollment period that begins when the active employment or the coverage ends. It is not open-ended, and it runs on Medicare's calendar rather than your employer's, so confirm the exact dates rather than assuming you have a full year.