How to Sign Up for Medicare: A Step-by-Step Guide
Signing up for Medicare is usually straightforward once you know when to enroll and whether you need to apply.
Some people are automatically enrolled in Medicare Parts A and B when they turn 65. Others need to sign up through Social Security.
After helping Medicare clients for more than 15 years, I've found the biggest mistakes usually aren't made during the application itself.
They happen when someone assumes they're automatically enrolled, or delays Part B without understanding how their employer coverage works.
If you've been receiving Social Security benefits for at least four months before turning 65, you'll generally be enrolled automatically.
Otherwise, you'll usually need to apply through Social Security.
In this guide, I'll walk you through when to sign up, how to apply, what to do if you're still working, and the coverage decisions you'll need to make afterward.
Step 1: Find Out if You're Automatically Enrolled
Whether you need to apply depends mostly on whether you're already receiving Social Security benefits.
Already Collecting Social Security
If you've received Social Security retirement benefits for at least four months before turning 65, you'll generally be enrolled in Parts A and B automatically.
Your Medicare card usually arrives about three months before your coverage starts.
No separate application is typically needed.
Not Collecting Social Security Yet
If you haven't started Social Security by 65, you'll generally need to sign up yourself.
You don't have to start retirement benefits to get Medicare.
This is the path for most people who are still working or delaying retirement.
Different procedures can apply if you receive Railroad Retirement Board benefits or live outside the United States.
The most common enrollment confusion we hear isn't about the application.
It's people who assume Medicare will "just show up" at 65 because a friend's did — when their friend was already collecting Social Security and they aren't.
If you're within a few months of 65 and haven't received a card or a welcome package, don't wait. Check your status in your my Social Security account or call Social Security.
Step 2: Know When You Can Sign Up
Most people first become eligible for Medicare at 65.
Your Initial Enrollment Period lasts seven months: the three months before your birthday month, your birthday month, and the three months after.
When you sign up inside that window determines when coverage starts.
Example: Turning 65 in July
If you're enrolling yourself for the first time, signing up during the three months before your 65th birthday month generally allows Part B coverage to begin on the first day of your birthday month.
If you enroll during your birthday month or the following three months, coverage generally starts the first day of the following month.
One wrinkle: if your birthday falls on the first of the month, your whole enrollment window shifts one month earlier. Medicare.gov explains this on its coverage start dates page.
What You'll Need to Sign Up for Medicare
Before starting your application, have this information ready.
- Your Social Security number
- Your date and place of birth
- Information about your current health insurance, if applicable
- Your employment and employer health coverage dates, if you're applying for Part B after age 65
- Your preferred Medicare coverage start date, when you're eligible to request one
Social Security may ask for additional information depending on your situation.
Helpful tip: You don't have to apply for Social Security retirement benefits to enroll in Medicare. You can sign up for Medicare while you keep working and delay retirement benefits.
Step 3: Apply for Medicare Through Social Security
If you need to enroll yourself, Social Security handles your Part A and Part B application.
You have three ways to do it.
| Method | How | Good For |
|---|---|---|
| Online | SSA.gov/medicare/sign-up | Most people turning 65 with a straightforward situation |
| Phone | Call 1-800-772-1213 (TTY 1-800-325-0778) | Questions about your eligibility or which application applies |
| In person | Local Social Security office (find yours) — an appointment can cut wait times | Complicated work histories, or if you prefer face-to-face help |
Online is the fastest route for most of our clients.
Applying Online: What to Expect
- Go to Social Security's Medicare sign-up page and choose to apply for Medicare only if you aren't ready to start retirement benefits.
- Answer the questions about you and your coverage. This is where you'll enter your current health insurance and employment details.
- Review and submit. Save the confirmation information Social Security gives you so you can check your application's status.
- Watch your mail. Social Security may contact you if it needs more information, and your Medicare card arrives once your enrollment is processed.
If you're signing up for Part B later because your employer coverage is ending, the process is different.
You'll typically file form CMS-40B along with CMS-L564, which your employer completes to confirm your group coverage. Both are on Social Security's Part B Special Enrollment Period page.
In the remarks section, write the month and year you want Part B to begin so there's no gap after your employer plan ends.
Step 4: Decide Whether to Enroll in Part A and Part B
Most people enroll in both parts as soon as they're eligible.
But if you're still working, the right timing depends on the kind of coverage you have.
Medicare Part A
Part A covers inpatient hospital care, skilled nursing facility care, hospice, and some home health care.
Most people get Part A premium-free because they (or a spouse) worked and paid Medicare taxes for at least 10 years.
Medicare Part B
Part B covers doctor visits, outpatient care, lab work, and other medically necessary services.
Part B has a monthly premium, and that's why some people still working at 65 consider delaying it.
Whether you can delay safely usually comes down to one question: is your coverage based on current employment? Medicare.gov's sign-up timing tool walks through each situation.
| Your Coverage at 65 | Can You Usually Delay Part B Without a Penalty? |
|---|---|
| Group plan from your or your spouse's current job (20+ employees) | Generally yes — you get an 8-month Special Enrollment Period after the job or coverage ends |
| Group plan from a current job with fewer than 20 employees | Often no — Medicare is usually primary, so the employer plan may not pay much without Part B |
| COBRA | No — COBRA doesn't extend your Special Enrollment Period |
| Retiree coverage | No — it isn't based on current employment |
| Marketplace (ACA) plan | No — you'll generally want to enroll during your Initial Enrollment Period |
| TRICARE | No — TRICARE For Life generally requires Parts A and B |
For most people turning 65, qualifying group health coverage through their own or their spouse's current employment is the main reason they can delay Part B without a late enrollment penalty.
Other special enrollment protections may apply in limited circumstances.
If you're unsure how your employer plan coordinates with Medicare, ask your benefits administrator in writing which pays first before you decide.
If you delayed Part B because you had qualifying employer coverage, you generally have an eight-month Special Enrollment Period after employment ends or that coverage ends, whichever happens first.
The eight-month window does not restart or extend because you elect COBRA.
If you want Part B to begin immediately after employer coverage ends, apply before that coverage ends.
Miss the window, and you may be stuck waiting for the General Enrollment Period — with a penalty added to your premium for as long as you have Part B.
If You Contribute to an HSA
If you're contributing to an HSA and plan to enroll in Medicare after age 65, pay close attention to your enrollment date.
Premium-free Part A can begin retroactively for up to six months, but not before your 65th birthday month.
Contributions made during months when Medicare coverage is effective may create tax problems.
Consider stopping HSA contributions six months before applying for Medicare or Social Security benefits, and confirm the timing with a tax professional.
Step 5: Receive Your Medicare Card
Once your enrollment is processed, your Medicare card will arrive in the mail.
It shows:
- Your Medicare number
- Your Part A effective date
- Your Part B effective date, if you enrolled
Check both dates as soon as the card arrives.
Those dates control when you can use Medicare.
If you're 65 or older, your Part B effective date generally marks the beginning of your six-month Medigap Open Enrollment Period.
Treat your Medicare number like a Social Security number. Share it only with doctors, insurers, and organizations you trust.
Medicare won't call you out of the blue asking for it. Our guide on how to stop Medicare scam calls explains what to watch for.
Step 6: Choose How You Want to Receive Medicare Coverage
With Parts A and B in place, you have two main paths.
| Feature | Original Medicare | Medicare Advantage |
|---|---|---|
| Doctors | Any provider nationwide who accepts Medicare | Provider access depends on plan rules and network requirements |
| Supplemental coverage | Can add a Medigap policy | Can't use Medigap with the plan |
| Drug coverage | Add a separate Part D plan | Many plans include it |
| Plan changes | Medicare benefits are set by law | Benefits, networks, and costs can change each year |
One difference worth knowing: Medicare Advantage plans have an annual out-of-pocket limit for covered Part A and Part B services, while Original Medicare alone generally does not.
Neither path is right for everyone. Your doctors, prescriptions, travel habits, and budget should drive the decision.
Our guide to Original Medicare vs. Medicare Advantage covers the tradeoffs in depth.
For clients who can afford the premiums, I usually lean toward Original Medicare with a Medigap plan.
Your first six months on Part B are often the easiest time you'll ever have to get Medigap without health questions. If you start on Medicare Advantage and want to switch to Medigap later, you may have to pass medical underwriting.
Step 7: Consider Additional Coverage
If you choose Original Medicare, you'll likely want coverage for the costs it leaves behind and for prescriptions.
Medicare Supplement (Medigap) Insurance
Medigap helps pay deductibles, copays, and coinsurance that Original Medicare doesn't cover.
Your six-month Medigap Open Enrollment Period generally begins the first month you're both 65 or older and enrolled in Medicare Part B.
During this period, insurers generally cannot deny you a Medigap policy or charge more because of your health.
After it ends, most states allow medical underwriting unless you have a guaranteed issue right.
Most of our new-to-Medicare clients compare Plan G and Plan N first.
Medicare Part D
Part D covers outpatient prescription drugs, and you can generally join a standalone plan once you have Part A or Part B.
If you're eligible for Medicare Part D and go 63 or more consecutive days without Part D or other creditable prescription drug coverage after your applicable enrollment period, you may face a late enrollment penalty when you join a Part D plan.
Employer drug coverage often counts as creditable. Your plan should send a yearly notice that tells you whether it does — keep it.
Applying for Medicare is often straightforward. Understanding when to enroll and how your existing coverage works is what matters most.
What Happens if You Miss Your Medicare Enrollment Period?
If you miss your Initial Enrollment Period and don't qualify for a Special Enrollment Period, you'll generally need to use the General Enrollment Period.
It runs from January 1 through March 31 each year, and coverage starts the month after you sign up.
You may also owe a late enrollment penalty.
For Part B, that's generally an extra 10% of the standard premium for each full 12-month period you could have had Part B but didn't. In most cases, it lasts as long as you have Part B.
Medicare.gov has full details on late enrollment penalties and how to avoid them.
Frequently Asked Questions
Can I sign up for Medicare before age 65?
Yes, in some situations.
People who receive Social Security disability benefits are generally enrolled after 24 months. People with ALS or End-Stage Renal Disease may qualify sooner.
Do I have to visit a Social Security office?
No.
Many people can complete enrollment entirely online or by phone.
Can I enroll in Medicare without retiring?
Yes.
You can have Medicare while you keep working, and you don't have to start Social Security benefits to enroll.
Do I need Part B if I'm still working?
It depends on your employer's size and your coverage.
Group coverage from a current employer with 20 or more employees usually lets you delay Part B without a penalty. At a smaller employer, Medicare is often primary, so delaying Part B can leave real gaps.
Does COBRA let me delay Medicare?
Not for Part B.
Your eight-month Special Enrollment Period is tied to when your job or employer coverage ends, not when COBRA ends.
Do I buy Medigap through Social Security?
No.
Medigap policies are sold by private insurance companies. Social Security only handles your Part A and Part B enrollment.
The Bottom Line
For most people, signing up for Medicare starts with finding out whether enrollment will happen automatically.
If you're already collecting Social Security, watch for your card. If you're not, apply through Social Security during the three months before your birthday month so your coverage starts on time.
If you're still working, confirm your coverage is based on current employment before delaying Part B — and don't count on COBRA or retiree coverage to protect you.
Once your Part B start date is set, plan around it. If you're 65 or older, that date generally begins your Medigap Open Enrollment Period, which is often the easiest time to lock in a Medigap plan.
My advice: start reviewing your options three to six months before your coverage begins. That leaves time to enroll, compare plans, and avoid the timing mistakes that cost people the most.
If you'd like a second set of eyes on your situation, a licensed agent can help — just be thoughtful about who you work with. Our guide on choosing a Medicare agent explains what to look for.
