Written By

Greg Wohl

Licensed Medicare Specialist

Medicare enrollment does not require an agent or broker. You can enroll in Parts A and B directly through the Social Security Administration, and you can compare and enroll in Part D and Medicare Advantage plans through Medicare's official Plan Finder tool.

That said, the process has more moving parts than most people expect. Enrollment windows are strict, and missing a deadline can result in permanent late enrollment penalties or gaps in coverage. This guide gives you a complete, step-by-step walkthrough so you can enroll confidently on your own.

Key Takeaways

Parts A and B are enrolled through Social Security: You apply for Medicare Parts A and B at ssa.gov or by calling 1-800-772-1213. If you are already receiving Social Security benefits, you are typically enrolled automatically at 65.
Your Initial Enrollment Period is 7 months: It begins 3 months before your 65th birthday month, includes your birthday month, and ends 3 months after. Enrolling in the first 3 months means coverage starts on the first day of your birthday month.
Part D and Medicare Advantage are enrolled separately: After enrolling in Parts A and B, you use Medicare Plan Finder at medicare.gov/plan-compare to compare and enroll in a Part D drug plan or Medicare Advantage plan.
Working past 65 changes the rules: If you have employer coverage through a company with 20 or more employees, you can delay Medicare without penalty. The rules are different for smaller employers.
Medigap requires separate enrollment: If you want a Medicare Supplement (Medigap) plan, you apply directly with a private insurer. Your 6-month Medigap Open Enrollment Period starts when you enroll in Part B at 65.
Penalties for late enrollment are permanent: Missing your Part B or Part D enrollment window without a qualifying reason results in a permanent premium surcharge. Act within your enrollment window to avoid this.

Step 1: Determine When You Need to Enroll

Before doing anything else, figure out which enrollment scenario applies to you. This determines your timeline and whether you can delay enrollment without penalty.

Scenario A: You are turning 65 and not working (or working for a small employer). You should enroll in Medicare Parts A and B during your Initial Enrollment Period (IEP). Your IEP is a 7-month window: the 3 months before your birthday month, your birthday month itself, and the 3 months after. Enrolling in the first 3 months of your IEP means your coverage starts on the first day of your birthday month.

Scenario B: You are turning 65 and have employer coverage through a company with 20 or more employees. You can delay Part B enrollment without penalty as long as you maintain that employer coverage. You will have a Special Enrollment Period (SEP) to enroll in Part B within 8 months of losing that coverage or leaving employment, whichever comes first.

Scenario C: You are already receiving Social Security benefits before turning 65. You will be automatically enrolled in Medicare Parts A and B. Your Medicare card will arrive in the mail about 3 months before your 65th birthday.

Scenario D: You are under 65 and qualify due to disability. After receiving Social Security Disability Insurance (SSDI) for 24 months, you are automatically enrolled in Medicare.

Step 2: Enroll in Medicare Parts A and B

If you are not automatically enrolled, here is how to sign up:

Online (recommended): Go to ssa.gov/medicare and click "Apply for Medicare Only." You will need your Social Security number, date of birth, and basic personal information. The online application takes about 10 to 15 minutes.

By phone: Call the Social Security Administration at 1-800-772-1213, Monday through Friday, 8 a.m. to 7 p.m. ET.

In person: Visit your local Social Security office. Find the nearest office at ssa.gov/locator.

What you will need:

Social Security number
Date and place of birth
Citizenship or immigration status
If applicable: employer and insurance information for any current health coverage
If applicable: documentation of creditable employer coverage if you are delaying Part B

After applying, you will receive a confirmation and your Medicare card by mail within 4 to 6 weeks. Your Medicare number will be a unique 11-character alphanumeric identifier (not your Social Security number).

Step 3: Decide Between Medicare Advantage and Original Medicare

Once you have Parts A and B, you need to decide how you want to receive your Medicare benefits. This is the most consequential decision in the enrollment process.

Option 1: Keep Original Medicare (Parts A and B) and add a standalone Part D drug plan plus, optionally, a Medigap supplement. This gives you the broadest provider access (any doctor or hospital that accepts Medicare nationwide) and the most predictable out-of-pocket costs if you add Medigap.

Option 2: Enroll in a Medicare Advantage plan (Part C), which replaces Original Medicare and typically includes drug coverage. Advantage plans often have $0 premiums and extra benefits like dental and vision, but restrict you to a network of providers.

The right choice depends on your health, your doctors, your medications, and how much you value flexibility versus extra benefits. If you are unsure, this is the point where consulting an independent Medicare advisor can save you from making a costly mistake, even if you handle the actual enrollment yourself.

Step 4: Enroll in a Part D or Medicare Advantage Plan

To compare and enroll in a Part D drug plan or Medicare Advantage plan, use the official Medicare Plan Finder at medicare.gov/plan-compare.

Here is how to use it effectively:

Create an account or continue as a guest. Creating an account saves your information for future comparisons.
Enter your ZIP code to see plans available in your area.
Enter your medications. This is the most important step. Enter every drug you take, including the exact dosage and quantity, to see accurate drug cost estimates under each plan.
Enter your preferred pharmacies. Drug costs vary by pharmacy. Enter your preferred pharmacy to see costs specific to where you fill prescriptions.
Filter and compare plans. Sort by total estimated cost (premium plus drug costs), Star Rating, and out-of-pocket maximum.
Enroll online. Once you have selected a plan, you can complete enrollment directly through the Plan Finder. You will need your Medicare number.

You can also enroll by calling the plan directly or by calling Medicare at 1-800-MEDICARE (1-800-633-4227).

Step 5: Enroll in Medigap (If You Chose Original Medicare)

If you chose Original Medicare rather than Medicare Advantage, you should strongly consider adding a Medigap (Medicare Supplement) plan to cover the gaps Original Medicare leaves, including the Part A deductible, Part B coinsurance, and skilled nursing facility costs.

Your Medigap Open Enrollment Period is the most important window for this. It begins on the first day of the month you turn 65 and are enrolled in Part B, and lasts 6 months. During this window, insurers cannot deny you coverage or charge higher premiums based on your health history.

After this window closes, insurers in most states (including Florida) can use medical underwriting, which means they can deny coverage or charge more based on pre-existing conditions.

To enroll in Medigap:

Compare plans at medicare.gov/medigap-supplemental-insurance-plans or use a comparison tool
Contact insurers directly to apply, or work with an independent broker who can compare rates across multiple carriers
Plan G is the most comprehensive Medigap plan available to new enrollees in 2026 and covers virtually all Medicare cost-sharing except the Part B deductible

Medigap plans are standardized by letter (Plan G, Plan N, etc.), so the coverage is identical regardless of which insurer you choose. The only difference is the premium, which varies by insurer, your age, and your location.

Your Medicare Enrollment Checklist

Use this checklist to make sure you complete every step:

Determine your enrollment scenario (turning 65, already on Social Security, working with employer coverage, or under 65 with disability)
Identify your Initial Enrollment Period or Special Enrollment Period dates
Apply for Parts A and B at ssa.gov or by calling 1-800-772-1213
Decide between Medicare Advantage and Original Medicare based on your doctors, drugs, and health needs
Use Medicare Plan Finder (medicare.gov/plan-compare) to compare Part D or Medicare Advantage plans with your actual medications entered
Enroll in your chosen plan before your enrollment window closes
If you chose Original Medicare, enroll in Medigap during your 6-month Open Enrollment Period
Confirm your coverage is active by logging into mymedicare.gov after your start date

If at any point you are unsure about which plan to choose, an independent Medicare advisor can help you compare options at no cost. Schedule a free consultation with our licensed specialists.