How to Sign Up: A Guide to Medicare Enrollment

What if you already have health insurance?

Even if you are turning 65, you may not have to enroll in Medicare. Here are circumstances under which you can delay enrolling and not face any late penalties.

• You are still working and have comprehensive health insurance through your employer.
• Your spouse is working and you are covered under her or his health insurance.

Even if you have employer-based insurance, your company may require that you enroll in Medicare Parts A and B, and your work insurance becomes a secondary program that fills gaps in Medicare coverage. You should check with your employer to be sure.

Keep in mind that not all health insurance coverage is created equal. Here are some scenarios under which you may have health coverage but still need to sign up for Medicare when you turn 65.

• You get your coverage through the Affordable Care Act’s (ACA) health insurance marketplace. Under the ACA, once you turn 65 you must transition from an ACA plan to Medicare.
• You have COBRA. If you lost your job and signed up for COBRA to extend your employer’s health coverage, this does not protect you against late penalties for not signing up for Medicare.
• You are covered under TRICARE. This program for retired military members is considered secondary coverage. This means that you must enroll in Medicare when you are eligible, and then TRICARE will fill in the gaps for some services Medicare doesn’t cover.
• You have a retiree health plan. These programs also are designed to fill in gaps Medicare doesn’t cover. They don’t substitute for Medicare, and the rules say you still need to enroll in that program when you turn 65.

Even if you have qualifying health insurance that doesn’t require you to sign up for Medicare at 65, you can still elect to enroll in Medicare Part A. The vast majority of enrollees won’t have to pay any premium for Part A, so enrolling will get you into the system and may make it easier for you to sign up for Part B when you’re ready.

Late enrollment penalty

If you don’t have the kind of health insurance that allows you to delay enrolling in Part B when you are first eligible, you will likely be subject to a late enrollment penalty. This penalty will increase your monthly Part B premium 10 percent for every 12 months you are late in enrolling. So the penalty increases the longer you go without Part B coverage. And you will have to pay that higher premium for as long as you have Medicare.

Open Enrollment Period

The open enrollment period for Medicare lasts from Oct. 15 to Dec. 7, but don’t be misled. This is not the period for Americans to enroll in Medicare for the first time (unless, of course, the time frame happens to overlap with your initial enrollment period when you turn 65). The open enrollment period is a window during which people who already have Medicare review their coverage and decide whether to make any changes — for example, switching their Part D prescription drug plan or moving from one Medicare option to another.

Special Enrollment Period

You’re over 65 and have been relying on health insurance through your job or your spouse’s job. Then, suddenly, one of you is laid off or you just decide to retire. That will trigger a special enrollment period (SEP) during which you can sign up for Medicare and won’t face any penalty for having delayed signing up for Part B. You’ll have eight months after losing your insurance to enroll in Medicare without being subject to a Part B premium penalty. When you enroll you will be asked to provide a form from your or your spouse’s employer to prove that you have had health insurance from the time you turned 65 until your insurance was dropped.

Editor’s note: This article has been updated with new information for 2023.

Dena Bunis covers Medicare, health care, health policy and Congress. She also writes the Medicare Made Easy column for the AARP Bulletin. An award-winning journalist, Bunis spent decades working for metropolitan daily newspapers, including as Washington bureau chief for the Orange County Register and as a health policy and workplace writer for Newsday.