How to Apply for Medicare: A Step-by-Step Guide

Applying for Medicare is one of the most important steps you will take as you approach age 65. The process is simpler than many people expect, but timing matters. Signing up too late can lead to gaps in coverage and permanent penalties on your premiums.

This guide walks you through when to apply, how to apply, what documents you need, and what to expect after you submit your application. Whether you plan to apply online, by phone, or in person, the steps are straightforward once you know the timeline.

When to Apply: The Initial Enrollment Period

Your Initial Enrollment Period (IEP) is the first and best window to sign up for Medicare. It is a 7-month window that centers on the month you turn 65. The window opens 3 months before your birthday month, includes your birthday month, and closes 3 months after.

For example, if you turn 65 in June, your IEP runs from March through September. The month you enroll within this window determines when your coverage begins. The earlier you enroll, the sooner you are covered.

Here is how your enrollment timing affects your coverage start date:

• Months 1 through 3 (before your birthday month): Coverage starts the first day of your birthday month.
• Month 4 (your birthday month): Coverage starts the first day of the following month.
• Months 5 through 7 (after your birthday month): Coverage is delayed by one to three months after you sign up.

If your birthday falls on the first day of the month, your IEP shifts one month earlier. For someone born on June 1, the IEP would run from February through August instead of March through September.

The bottom line is simple: sign up during the first three months of your IEP. This gives you the earliest possible coverage start date and avoids any gap between turning 65 and having Medicare.

Automatic Enrollment: When You Do Not Need to Apply

Not everyone needs to fill out a Medicare application. If you are already receiving Social Security retirement benefits when you turn 65, the Social Security Administration automatically enrolls you in Medicare Parts A and B. Your Medicare card arrives in the mail roughly three months before your 65th birthday.

The same applies if you are receiving Social Security Disability Insurance (SSDI). After 24 months of SSDI payments, you are automatically enrolled in Medicare Parts A and B. You do not need to fill out an application.

Automatic enrollment covers both Part A and Part B. If you do not want Part B, you need to take action to decline it. If you do nothing, Part B premiums will be deducted from your Social Security check. Many people keep both parts, but some decline Part B because they have qualifying employer coverage.

People diagnosed with ALS (Lou Gehrig's disease) are a special case. If you qualify for SSDI due to ALS, Medicare starts the same month your disability benefits begin. There is no 24-month waiting period.

How to Apply Online at SSA.gov

Applying online through the Social Security Administration website is the fastest and most convenient method. The application is available 24 hours a day, 7 days a week, and takes about 10 to 15 minutes to complete.

Here is how to apply online step by step:

• Step 1: Go to SSA.gov and click on the Medicare section. You can also go directly to the Medicare application page.
• Step 2: Create or sign in to your my Social Security account. You will need to verify your identity if this is your first time.
• Step 3: Choose whether you want to apply for Medicare only or for both Medicare and Social Security retirement benefits.
• Step 4: Fill out your personal information, including your name, date of birth, Social Security number, and citizenship status.
• Step 5: Indicate whether you want Part A only or both Part A and Part B. Review your selections and submit the application.

After you submit your application, you will receive a confirmation number. Save this number for your records. Social Security will contact you if they need additional information. In most cases, no follow-up is needed.

How to Apply by Phone

If you prefer to speak with someone, you can apply for Medicare by calling Social Security at 1-800-772-1213. TTY users can call 1-800-325-0778. Phone lines are open Monday through Friday, from 8 a.m. to 7 p.m. local time.

When you call, a representative will walk you through the application. Have your Social Security number, date of birth, and information about any current health insurance ready before you call. The representative will ask the same questions that appear on the online application.

Wait times can be long, especially during peak enrollment periods. Calling early in the morning or later in the week may reduce your wait. You can also request a callback instead of waiting on hold.

How to Apply in Person

You can visit your local Social Security office to apply for Medicare in person. This option is helpful if you have a complicated situation, need help understanding your options, or simply prefer face-to-face assistance.

It is strongly recommended that you schedule an appointment before visiting. Walk-in visits are accepted, but wait times can be very long. You can schedule an appointment by calling 1-800-772-1213.

When you visit, bring the following documents:

• Your Social Security card or a document showing your Social Security number
• Proof of U.S. citizenship or lawful permanent residency, such as a birth certificate, U.S. passport, or green card
• Information about any current health insurance, including your policy number and employer name
• If applying during a Special Enrollment Period, proof of qualifying employer coverage and the date it ended

Applying for Part A Only vs. Part A and Part B

When you apply for Medicare, you choose whether to sign up for Part A only or both Part A and Part B. Understanding the difference helps you make the right choice for your situation.

Part A covers hospital stays, skilled nursing facility care, hospice, and some home health services. Most people qualify for premium-free Part A if they or their spouse worked and paid Medicare taxes for at least 10 years (40 quarters). Because it is free for most people, there is generally no reason to delay Part A enrollment.

Part B covers doctor visits, outpatient care, preventive services, and medical equipment. Part B has a monthly premium that most people pay. In 2025, the standard Part B premium is $185.00 per month.

You may choose to enroll in Part A only if you meet one of these conditions:

• You are still working at 65 and your employer has 20 or more employees, making your employer plan primary
• Your employer coverage is comprehensive and you want to avoid paying the Part B premium while still working
• Your spouse's employer plan covers you and the employer has 20 or more employees

Important: if your employer has fewer than 20 employees, Medicare is your primary insurance at 65. You generally need to enroll in both Part A and Part B during your IEP to avoid coverage gaps and penalties.

Also keep in mind that enrolling in Part A makes you ineligible to contribute to a Health Savings Account (HSA). If you have an HSA, stop contributing before you enroll. Part A can be backdated up to six months, so plan accordingly.

Documents You Need to Apply

Having the right documents ready speeds up the application process. The exact documents you need depend on your situation, but the following list covers what most applicants will need.

• Social Security number: Required for all applications. If applying online, you will enter it during the sign-in process.
• Proof of citizenship or residency: A birth certificate, U.S. passport, or permanent resident card (green card) is acceptable.
• Current health insurance information: Your insurance card, policy number, and the name and address of your employer if you have employer coverage.
• Employment information: If you are using a Special Enrollment Period, you may need a letter from your employer confirming your coverage dates.

For online applications, you generally do not need to upload documents. Social Security verifies most information electronically. For phone or in-person applications, you may be asked to provide physical copies or mail documents to your local office.

How Long Does Processing Take?

Most Medicare applications are processed within a few weeks. Online applications tend to be the fastest. You will receive a confirmation when your application is submitted, and Social Security will contact you if anything else is needed.

After your application is approved, your Medicare card will be mailed to you. Most people receive their card within 30 days of approval. The card shows your Medicare number, the parts you are enrolled in, and the date your coverage starts.

Your coverage start date is based on when you enrolled during your IEP, not on when your application is processed. Even if processing takes several weeks, your coverage will be backdated to the correct start date based on your enrollment timing.

If you need proof of coverage before your card arrives, you can call Medicare at 1-800-633-4227. A representative can confirm your enrollment and provide your Medicare number over the phone.

Common Mistakes to Avoid When Applying

The Medicare application itself is straightforward, but many people make mistakes related to timing and coverage decisions. Here are the most common errors and how to avoid them.

• Waiting too long to sign up: Enrolling in the last months of your IEP delays your coverage start date by up to three months. Sign up in the first three months for the earliest coverage.
• Missing the IEP entirely: If you miss your IEP and do not have qualifying employer coverage, you must wait for the General Enrollment Period (January 1 through March 31) and your coverage will not start until July 1. You will also face a permanent late enrollment penalty.
• Confusing COBRA with employer coverage: COBRA continuation coverage does not count as current employer coverage. If you elect COBRA instead of signing up for Part B, you will face the late enrollment penalty when you eventually enroll.
• Thinking retiree benefits protect you: Retiree health plans from a former employer do not qualify you for a Special Enrollment Period. You must sign up during your IEP even if you have retiree coverage.
• Forgetting about HSA rules: Enrolling in any part of Medicare, including Part A, makes you ineligible for new HSA contributions. Since Part A can be retroactive up to six months, stop HSA contributions at least six months before your Medicare start date to avoid tax penalties.
• Not knowing your employer size matters: If your employer has fewer than 20 employees, Medicare becomes your primary insurance at 65. You need both Part A and Part B. If your employer has 20 or more employees, your employer plan is primary and you can safely delay Part B.

Special Enrollment Period for Working People

If you delay Medicare enrollment because you have employer health coverage through your own job or your spouse's job, you qualify for a Special Enrollment Period (SEP) when that coverage ends. The employer must have 20 or more employees for this to apply.

The SEP gives you 8 months to enroll in Part B after your employer coverage ends or after you stop working, whichever comes first. During this window, you can sign up without penalty. Coverage generally begins the first of the month after you enroll.

To use the SEP, you will need to provide proof that you had qualifying employer coverage. Social Security uses Form CMS-L564, which your employer or health plan fills out. This form confirms your coverage dates and your employer's size. Have your employer complete this form before you submit your Medicare application.

Do not wait until the last month of your SEP. If you enroll early in the window, your coverage starts sooner. If you miss the SEP entirely, you will need to wait for the General Enrollment Period and will face permanent late enrollment penalties.

What Happens After You Are Approved

Once your Medicare application is approved, several things happen. Understanding the next steps helps you get the most out of your new coverage right away.

• You receive your Medicare card: Your red, white, and blue card arrives in the mail. It lists your Medicare number and confirms the parts you are enrolled in. Keep this card safe and carry it when visiting doctors or hospitals.
• You can add a Part D drug plan: Original Medicare does not include prescription drug coverage. You can enroll in a standalone Part D plan through Medicare.gov or by contacting plans directly. You have a window around your Medicare start date to enroll without penalty.
• You can choose Medicare Advantage: Instead of Original Medicare, you can enroll in a Medicare Advantage plan (Part C). These plans are offered by private insurers and generally include Part A, Part B, and often Part D coverage in one plan.
• You can buy a Medigap policy: Medigap (Medicare Supplement) policies help cover out-of-pocket costs like deductibles and coinsurance under Original Medicare. The best time to buy is during your Medigap Open Enrollment Period, which starts when you are 65 and enrolled in Part B.

Part B premiums are typically deducted from your Social Security check. If you are not receiving Social Security, Medicare will send you a bill every three months. You can set up automatic payments through your Medicare account.

Tips for a Smooth Application Process

A few simple steps can make your Medicare application go smoothly and help you avoid delays or problems down the road.

• Start early: Begin thinking about Medicare at least six months before you turn 65. This gives you time to understand your options, gather documents, and apply during the first month of your IEP.
• Check your work credits: Sign in to your my Social Security account at SSA.gov to verify you have at least 40 quarters of coverage. This confirms you qualify for premium-free Part A.
• Talk to your employer: If you are still working, ask your HR department how Medicare will interact with your employer plan. Get clarity on whether your employer has 20 or more employees and which plan will be primary.
• Contact SHIP for free help: Your State Health Insurance Assistance Program (SHIP) offers free, unbiased counseling about Medicare. Trained counselors can help you understand your options and walk you through the application process.
• Keep records: Save your application confirmation number, any correspondence from Social Security, and copies of documents you submitted. These records are helpful if questions arise later.

The Bottom Line

Applying for Medicare is not complicated, but getting the timing right is essential. The best approach is to apply during the first three months of your Initial Enrollment Period for the earliest possible coverage. If you are already receiving Social Security, you may not need to apply at all because enrollment is automatic.

You have three ways to apply: online at SSA.gov, by phone at 1-800-772-1213, or in person at your local Social Security office. Online is the fastest option and available around the clock. Whichever method you choose, have your Social Security number, proof of citizenship, and current health insurance information ready.

The biggest mistakes people make are waiting too long, confusing COBRA with employer coverage, and not understanding how employer size affects their enrollment requirements. Avoiding these errors can save you from permanent premium penalties that add up over the rest of your life.

Once you are enrolled in Original Medicare, you can add prescription drug coverage through a Part D plan, choose a Medicare Advantage plan, or purchase a Medigap supplement policy. Take the time to compare your options so you get the coverage that works best for your health needs and budget.