The first thing to know about how to sign up for Medicare is that some people don't have to do anything at all, while others have to apply themselves. Which group you're in depends on one fact: whether you're already getting Social Security. This guide walks through how to tell which path is yours, how to apply through the Social Security Administration if you need to, and what you choose along the way.
Start here: are you automatic, or do you apply?
Before you do anything, settle one question, because it decides everything that follows. Are you already receiving Social Security or Railroad Retirement Board (RRB) benefits as you approach 65? If so, your enrollment is handled for you. If not, you have to apply, and the window to do it on time is narrow.
If you're already on Social Security, you're automatic
If you start collecting Social Security or RRB benefits before you turn 65, the government enrolls you in Medicare automatically. The same is true if you're under 65 and have received Social Security Disability Insurance (SSDI) for 24 months. You don't fill out anything.
Your red, white, and blue Medicare card arrives in the mail about three months before your 65th birthday (or, for SSDI, before your 25th month of benefits). When it shows up, you'll already be signed up for both Part A (hospital) and Part B (medical), with coverage starting the first day of the month you turn 65.
There's one decision the automatic path still leaves to you. Because Part B carries a monthly premium, you're allowed to decline it. Most people shouldn't. If you turn down Part B without other coverage that counts, you can owe a late penalty that follows you for as long as you have Part B, and you'll wait for a later enrollment window to pick it up. The one common exception is if you're still working with employer coverage, covered below.
If you're not automatic, here's how to apply
If you're approaching 65 and haven't started Social Security, the responsibility is yours. The Social Security Administration handles the application, and you have three ways to do it. Online is the fastest, but all three reach the same place.
| How to apply | What you do | Good to know |
|---|---|---|
| Online | Go to ssa.gov/medicare/sign-up and complete the application | Fastest option; you'll need a free "my Social Security" account, which takes a few minutes to set up |
| By phone | Call 1-800-772-1213 (TTY 1-800-325-0778) | A representative walks you through it; expect a wait at busy times |
| In person | Visit a local Social Security office | Best if you have questions or documents to bring; call ahead to confirm whether you need an appointment |
Through any of these, you're applying for Part A, Part B, or both. Apply during the three months before your birthday month and your coverage can begin the first day of the month you turn 65. The full set of windows, including what happens if you miss this one, is covered in our guide to Medicare enrollment periods.
What you'll need on hand
You don't need much, but having it ready makes the application go quickly. Gather your Social Security number, your birth certificate or other proof of birth, and proof of U.S. citizenship or lawful residence if you weren't born here. If you're delaying because you have job-based coverage, you may later need a form from your employer confirming when that coverage started and ended. SSA will tell you exactly what applies to your situation as you go.
After Parts A and B: the choices you make separately
Signing up through SSA gets you Original Medicare, Parts A and B. It does not, on its own, give you prescription drug coverage, an out-of-pocket cap, or the extras some plans offer. Those come from separate enrollments you handle after your Part A and B are in place, and you make them with the plans and insurers directly rather than through SSA.
You have a few directions to go from here:
- Add a Part D drug plan. Original Medicare doesn't cover most outpatient prescriptions, so most people enrolled in Parts A and B add a standalone Part D plan. You can compare plans and enroll using Medicare's Plan Finder at medicare.gov/plan-compare.
- Or switch to a Medicare Advantage plan. Instead of Original Medicare, you can choose a Medicare Advantage (Part C) plan, which bundles Parts A and B and usually drug coverage into one private plan. You enroll through the plan, also using the Plan Finder.
- Consider Medigap if you keep Original Medicare. A Medigap (Medicare Supplement) policy pays the deductibles and coinsurance Original Medicare leaves to you. You buy it from an insurer, not from SSA. Your best shot at any policy regardless of health is the six-month window that opens once you're both 65 and enrolled in Part B.
Deciding between Original Medicare plus Medigap and a Medicare Advantage plan is the bigger fork in the road, and it shapes your costs and which doctors you can see. Our guide to Original Medicare vs. Medicare Advantage lays out that comparison.
If you're still working at 65
Plenty of people keep working past 65 and stay on a current employer's health plan. If that coverage counts as creditable, you can delay Part B (and Part D) without a penalty and sign up later, when the job or the coverage ends.
When that happens, you get an eight-month Special Enrollment Period to enroll without penalty. Here's the trap worth knowing now: COBRA and retiree coverage do not count as current-employer coverage for this purpose, so neither one extends that window. If you're relying on COBRA after leaving a job, the Special Enrollment clock may already be running. Our guide to how Medicare works with other insurance explains the timing in detail before you make a decision you can't undo.
Frequently asked questions
Through Social Security. The Social Security Administration processes Medicare enrollment for Parts A and B, even though the program itself is Medicare. You can apply online at ssa.gov/medicare/sign-up, by phone at 1-800-772-1213, or at a Social Security office. The official walkthrough also lives on the Medicare page covering how to sign up.
Apply during the three months before the month you turn 65. Doing it in that window means your coverage can start the first day of your birthday month, with no gap. You can also sign up during the month you turn 65 or the three months after, but coverage then starts a little later.
If you're already receiving Social Security or Railroad Retirement Board benefits when you turn 65, you're enrolled automatically and your card arrives by mail. If you're under 65 and have gotten SSDI for 24 months, you're also enrolled automatically. If you haven't started Social Security, you must apply yourself.
Yes, you can take premium-free Part A and turn down Part B. But unless you have other coverage that counts, such as a current employer's plan, declining Part B can mean a lifelong late penalty when you do enroll. Think carefully before skipping it.
Learn More
- What is Medicare? Parts A, B, C, and D explained
- When to sign up for Medicare, and the late penalties
- Original Medicare vs. Medicare Advantage
- How Medicare works with other insurance (and the COBRA trap)
Find personalized help signing up for Medicare at brevy.com.
The information on Brevy.com is for educational purposes only and is not a substitute for professional legal, financial, or medical advice. Rules vary by state and program and change frequently. Always verify with the relevant agency or a qualified professional. Brevy is not a law firm, financial advisor, or healthcare provider.