When Do You Sign Up for Medicare? Every Enrollment Path Explained | Eligry

When do you sign up for Medicare? It’s one of the most common questions people ask — and one of the most confusing to answer. The truth is, there isn’t one single enrollment date. There are at least seven different paths onto Medicare, and which one applies to you depends on your age, your work situation, whether you’re already receiving Social Security, and sometimes even a medical diagnosis.

Get the timing wrong and you could face a permanent penalty on your premiums for the rest of your life. Here’s every enrollment path explained in plain English, so you know exactly when do you sign up for Medicare based on your specific situation.

1. Already on Social Security at 65: when do you sign up for Medicare? You don’t — it’s automatic

This is the path I took, and it catches a lot of people off guard. If you’re already receiving Social Security benefits (or Railroad Retirement Board benefits) when you turn 65, you don’t need to sign up for Medicare. Social Security does it for you.

About three months before your 65th birthday, a red, white, and blue Medicare card will show up in your mailbox. You’ll be automatically enrolled in both Medicare Part A (hospital insurance) and Medicare Part B (medical insurance). Your Part B premium — $202.90 per month in 2026 — will be automatically deducted from your Social Security check.

If you want Part A but don’t want Part B (because you still have employer coverage, for example), you can decline Part B. But you need to actively opt out — otherwise it starts automatically and the premiums start deducting.

2. Turning 65 and NOT on Social Security: the Initial Enrollment Period

If you haven’t started collecting Social Security yet — maybe you’re still working, maybe you’re delaying benefits to get a higher payout — nobody is going to enroll you automatically. You need to sign up for Medicare on your own.

You do this during your Initial Enrollment Period (IEP), which is a 7-month window centered around your 65th birthday. It starts 3 months before the month you turn 65, includes your birthday month, and extends 3 months after.

For example, if your birthday is in October, your IEP runs from July 1 through January 31 of the following year.

You can sign up through Social Security’s website, by calling Social Security at 1-800-772-1213, or by visiting your local Social Security office in person.

3. Still working at 65+ with employer coverage: when do you sign up for Medicare?

Here’s where the question of when do you sign up for Medicare gets complicated. If you’re 65 or older and still working for an employer that provides health insurance, you may not need to sign up for Part B right away — and you won’t face a penalty for waiting.

This applies if your employer has 20 or more employees. In that case, your employer plan is considered your “primary” insurance, and Medicare is secondary. You can delay Part B enrollment without penalty as long as you (or your spouse) are actively working and covered by the employer plan.

Most people in this situation sign up for Part A only when they turn 65 (it’s free for most people, so there’s no downside) and delay Part B until they retire or lose their employer coverage.

Once your employer coverage ends — whether you retire, get laid off, or the company drops the plan — you get a Special Enrollment Period (SEP). This gives you 8 months from the date your employer coverage ends to sign up for Part B without penalty. I cover the details of this transition in a separate guide for people losing employer coverage, because the rules are specific and the consequences of getting them wrong are serious.

COBRA does not count as employer coverage for Medicare purposes. If you leave your job and go on COBRA, that does not give you a Special Enrollment Period. You would need to sign up during your IEP or face the late enrollment penalty. This is one of the most common and costly mistakes people make. Medicare.gov has additional details on enrollment timing.

4. Under 65 on Social Security Disability (SSDI)

You don’t have to be 65 to qualify for Medicare. If you’re receiving Social Security Disability Insurance (SSDI), you become eligible for Medicare after you’ve been on SSDI for 24 months. That’s 24 months from when your disability benefits start — not 24 months from when you applied or were approved.

Just like the over-65 auto-enrollment, if you’re on SSDI, you’ll be automatically enrolled in Parts A and B once you hit that 24-month mark. Your Medicare card will arrive in the mail about three months before your coverage begins.

The coverage start date is the 25th month of your SSDI eligibility. So if your disability benefits started in January 2024, your Medicare coverage would begin in February 2026.

People who qualify for Medicare through disability often face additional challenges when shopping for Supplement plans. The federal Medigap guaranteed-issue rules only apply to people 65 and older. For under-65 Medicare beneficiaries, whether you can buy a Supplement plan depends entirely on your state’s laws. Some states require carriers to sell Medigap to under-65 beneficiaries; others don’t.

5. Diagnosed with ALS (Lou Gehrig’s disease)

This is the one exception to the 24-month waiting period. If you are diagnosed with ALS and qualify for SSDI, your Medicare coverage begins immediately — the same month your disability benefits start. There is no waiting period.

You are automatically enrolled in both Part A and Part B. This is a federal protection recognizing the progressive nature of ALS and the need for immediate coverage.

6. End-Stage Renal Disease (ESRD)

End-Stage Renal Disease — permanent kidney failure requiring dialysis or a kidney transplant — is the other way to qualify for Medicare under 65 regardless of disability status. You don’t need to be on SSDI to qualify.

The rules here are specific. Generally, your Medicare coverage begins the fourth month after you start dialysis. If you get a kidney transplant, the timeline is different. If you’re already on an employer plan when you start dialysis, there’s a 30-month coordination period where your employer plan pays first.

ESRD Medicare eligibility has its own application process through Social Security. The timing can be tricky, and coordination with any existing coverage is important. If you or a family member is dealing with this, talking to a Medicare advisor can help you avoid gaps.

7. Missed your window: the General Enrollment Period

If you didn’t sign up during your Initial Enrollment Period, you weren’t covered by an employer plan, and you don’t qualify for a Special Enrollment Period — you have to wait for the General Enrollment Period (GEP).

The GEP runs from January 1 through March 31 each year. If you sign up during this window, your coverage begins July 1 of that same year. That means you could have a gap of several months without coverage.

And remember — you’ll also face the late enrollment penalty: that permanent 10% Part B premium surcharge for every 12 months you should have been enrolled but weren’t.

The GEP is a safety net, but it’s not a good one. It’s designed as a last resort. The goal is to never need it — which is why understanding your IEP and SEP is so important.

Part A vs. Part B: do you need both?

Part A covers hospital stays, skilled nursing facility care, hospice, and some home health care. For most people, Part A is premium-free because you (or your spouse) paid Medicare taxes for at least 10 years. There’s rarely a reason to decline it.

Part B covers doctor visits, outpatient care, preventive services, durable medical equipment, and more. Part B has a monthly premium ($202.90 in 2026) and is the one people sometimes delay if they have employer coverage.

Most people need both. The question is when you start Part B, and whether you need it immediately or can defer it while you have other qualifying coverage.

After enrollment: the next big decision

Getting enrolled in Medicare is just step one. Once you have Parts A and B, you face the biggest decision of your Medicare journey: do you stay on Original Medicare and add a Medicare Supplement (Medigap) plan, or do you switch to a Medicare Advantage (Part C) plan?

That choice affects your doctors, your out-of-pocket costs, your prescription drug coverage, and your flexibility for the rest of your retirement. It’s also a decision that can be difficult to reverse later — especially if your health changes. If you chose Medicare Advantage and later regret it, you may have a 12-month trial right to switch.

Knowing when do you sign up for Medicare is just the starting point. The real question is what comes next — and that’s exactly the kind of decision that benefits from a 30-minute conversation with someone who knows every plan in your area and has no financial incentive to push you in one direction.

The bottom line

Medicare enrollment isn’t one-size-fits-all. Whether you’re auto-enrolled through Social Security, signing up during your IEP, waiting because of employer coverage, or qualifying through disability — the rules are different for each path, and the penalties for getting it wrong are real and permanent.

The single best thing you can do is understand which path applies to you and start planning early. If you’re within a year of any of these enrollment triggers, now is the time to talk to someone who can walk you through the specifics of when do you sign up for Medicare based on your exact situation.

Cindy Kowalski · Licensed Independent Medicare Advisor · Eligry LLC · NPN 21601670

We do not offer every plan available in your area. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options. Not affiliated with or endorsed by the U.S. government or the federal Medicare program.