How to Sign Up for Medicare Parts A and B.

The One Thing to Know Before Anything Else

You enroll in Medicare Parts A and B through Social Security — not through Medicare, not through an insurance company, and not through HealthCare.gov. Social Security handles the application. Medicare provides the coverage. This distinction trips up more people than any other part of the process.

Three ways to enroll: online at ssa.gov/medicare/sign-up, by phone at 1-800-772-1213, or in person at your local Social Security office. The online application takes 10–15 minutes and is the fastest option for most people.

What Parts A and B Actually Cover

Medicare has two foundational parts. Part A covers hospital-related care. Part B covers doctor and outpatient care. Together, they form "Original Medicare" — the federal baseline that everything else (Medigap, Medicare Advantage, Part D) is built on top of or replaces.

The Three Enrollment Periods — and When to Use Each One

When you enroll determines when your coverage starts and whether you'll pay a penalty. There are three windows, and only one of them applies to your situation.

Late-Enrollment Penalties: What They Cost and How Long They Last

The Part B penalty is the one that catches most people. It's permanent, it compounds, and it cannot be reversed. Understanding the math before your deadline is the single most important thing in this guide.

For a deeper look at how these penalties add up over time and how to prevent them, see 7 Costly Medicare Mistakes a Quote Helps You Avoid.

Working Past 65: When You Can — and Can't — Delay Part B

This is the most common source of confusion in Medicare enrollment. The rules are specific, and getting them wrong triggers permanent penalties.

You CAN delay Part B without penalty if: you're actively employed (not retired) and covered under a group health plan through your employer or your spouse's employer, and the employer has 20 or more employees. When you leave that job or lose that coverage, you get an 8-month Special Enrollment Period to sign up for Part B penalty-free.

You CANNOT delay Part B without penalty if: your coverage is through COBRA, a retiree health plan, the VA, TRICARE (with some exceptions), a health sharing ministry, a small employer with fewer than 20 employees, or an individual ACA Marketplace plan. None of these qualify as "creditable employer coverage" for the purpose of delaying Part B.

Documents You Need to Enroll

What you need depends on which enrollment period you're using. Everyone needs the basics. People using the Special Enrollment Period after employer coverage need additional employer verification.

For all enrollees: proof of age and identity (driver's license or passport), Social Security number, and proof of U.S. citizenship or legal residency.

For Special Enrollment Period (employer coverage ending): everything above plus CMS Form L564 (Request for Employment Information) — completed and signed by your employer's HR department — and CMS Form 40B (Application for Enrollment in Medicare Part B). Both forms are available at cms.gov.

If applicable: VA member number, TRICARE ID, or employer/union insurance card — depending on your current coverage situation.

Step-by-Step: How to Enroll Online

The fastest path for most people is enrolling online through Social Security. Here's exactly what the process looks like.

1. Go to ssa.gov/medicare/sign-up.

2. Log in with your my Social Security account (or create one — takes 5 minutes).

3. Select whether you want Part A only or Part A and Part B. Most people enrolling at 65 should select both. Select Part A only if you have qualifying employer coverage and are delaying Part B.

4. Complete the application — personal information, coverage history, payment preferences for Part B premium.

5. Submit and save your confirmation number. Your Medicare card will arrive by mail, typically within a few weeks.

6. If enrolling via SEP, mail or fax forms CMS-L564 and CMS-40B to your local Social Security office after submitting the online application.

Alternative methods: Call Social Security at 1-800-772-1213 (TTY: 1-800-325-0778), Monday–Friday 8 AM – 7 PM local time. Or visit your local Social Security office in person — bring all documents listed above.

What Comes After Parts A and B: The Four Coverage Paths

Enrolling in Parts A and B is step one. Step two is deciding how you want to use that coverage. There are four paths, and every Medicare beneficiary ends up on one of them. The right choice depends on how you use healthcare, what flexibility you want, and how much cost predictability matters to you.

For NC-specific guidance on the Medicare Advantage path, see How to Compare Medicare Advantage Plans in NC. For the Medigap path, see Medigap Plan G vs. Plan N in NC. For a broader look at NC plan availability by county, see Free Medicare Quotes in North Carolina.

Automatic Enrollment: Who Gets It and Who Doesn't

Automatically enrolled: If you're already receiving Social Security or Railroad Retirement Board benefits when you turn 65, you'll be automatically enrolled in Parts A and B. Your Medicare card arrives about 3 months before your 65th birthday. You can decline Part B if you have qualifying employer coverage.

Must enroll manually: If you're not yet collecting Social Security when you turn 65 — which is common for people still working or who delayed Social Security benefits — you must apply through ssa.gov yourself. There is no automatic enrollment for this group, and waiting too long triggers penalties.

Under 65 with a disability: If you've received Social Security Disability Insurance (SSDI) for 24 months, you're automatically enrolled in Medicare. If you have ALS (Lou Gehrig's disease) or End-Stage Renal Disease (ESRD), enrollment begins immediately upon diagnosis or the start of dialysis.

Frequently Asked Questions