Enrolling in Medicare for the First Time: A Step-by-Step Guide

Understanding Your Initial Enrollment Period

The Initial Enrollment Period (IEP) is your first and most important Medicare deadline. It is a 7-month window that runs from 3 months before the month you turn 65, includes your birthday month, and continues for 3 months after. This window exists whether or not you plan to claim Social Security, and missing it can lock you out of penalty-free enrollment for the rest of your life.

If your 65th birthday falls in August 2026, for example, your IEP runs from May 1, 2026 through November 30, 2026. There is a small twist for birthdays on the 1st of the month: Medicare treats you as turning 65 one month earlier for enrollment-timing purposes, so your IEP shifts back by one month.

When does coverage actually start?

The month you enroll inside your IEP changes when your coverage starts.

How to Apply for Medicare at 65

You enroll in Medicare Parts A and B through the Social Security Administration, not Medicare itself. There are three official ways to apply, and the right one depends on how comfortable you are with online tools and how complicated your situation is.

Option 1: Apply online at SSA.gov

This is the fastest method. Go to SSA.gov, click Medicare in the top menu, then Sign up for Medicare. You will create or sign in to a my Social Security account using Login.gov or ID.me, agree to the terms, and choose Medicare only if you are not also claiming Social Security retirement benefits. Have your Social Security number, date and place of birth, and current health coverage information handy. The whole application typically takes 15-20 minutes, and you receive a confirmation receipt at the end.

Option 2: Apply by phone

Call Social Security at 1-800-772-1213 (TTY 1-800-325-0778), Monday through Friday from 8:00 a.m. to 7:00 p.m. local time. A representative can take your application over the phone or schedule a call-back appointment. This is the best option if your situation involves employer coverage, a Special Enrollment Period, or other complications.

Option 3: Apply in person

You can sign up at any local Social Security office. Use the office locator on SSA.gov to find yours, and call ahead to confirm whether an appointment is required. Bring your Social Security card or number, a photo ID, and details of any current employer or retiree coverage.

What if I am already getting Social Security?

If you are already receiving Social Security or Railroad Retirement benefits when you approach 65, you are automatically enrolled in both Part A and Part B. Your red, white, and blue Medicare card typically arrives in the mail about 3 months before your coverage starts. You do not need to apply, but you do still need to decide whether to keep Part B (more on that next) and whether to add Part D and a Medigap policy.

Should You Delay Part B for Employer Coverage?

If you (or your spouse) are still working at 65 with group health coverage, you may be able to delay Part B without penalty. Whether you should is a different question, and it almost always comes down to employer size.

If you delay Part B based on qualifying current employer coverage, you get a Special Enrollment Period (SEP) that lets you sign up anytime while still covered, plus 8 months after the job or employer coverage ends (whichever comes first). One critical warning: COBRA and retiree coverage do not extend this SEP. The 8-month clock starts the month after your active employment ends, even if you take 18 months of COBRA.

Original Medicare + Medigap + Part D vs. Medicare Advantage

Once you have Part A and Part B (Original Medicare), you have a fork in the road. You can either supplement Original Medicare with a Medigap policy plus a standalone Part D drug plan, or you can replace Original Medicare with an all-in-one Medicare Advantage plan. Both choices have to be made during enrollment to avoid coverage gaps and missed windows.

For a deeper side-by-side cost analysis, see our full breakdown of Medigap vs. Medicare Advantage. If you lean toward Original Medicare, our guide to the best Medicare Supplement plans of 2026 compares the top-ranked carriers and plan letters. You can also compare quotes the right way with our Medicare Supplement shoppers guide.

What is new for 2026

Two changes affect first-time enrollees this year. First, the Part D out-of-pocket cap is $2,100 in 2026 (up from $2,000 in 2025), giving everyone enrolled in a Medicare drug plan a hard ceiling on covered prescription costs. Second, beginning January 1, 2026, there is a new Special Enrollment Period for people who enrolled in a Medicare Advantage plan based on incorrect provider directory information. If you discover your doctor or hospital was wrongly listed as in-network, you get 3 months after coverage starts to switch plans.

Why timing your Medigap purchase matters

Your Medigap Open Enrollment Period is a one-time, 6-month window that starts the first month you are both 65 or older and enrolled in Part B. During this window, insurers must sell you any plan they offer, cannot use medical underwriting, and cannot charge more for pre-existing conditions. Miss it and in most states you can be denied coverage or charged higher rates based on your health. For full details on this window, read our complete guide to Medicare Supplement Open Enrollment.

Most new enrollees choose Medicare Supplement Plan G or Plan N for the best balance of coverage and premium. Healthy enrollees who want catastrophic-only coverage often consider High-Deductible Plan G. Plan F is closed to people who became eligible after 2020, as explained in our Plan F guide.

Late Enrollment Penalties Explained

Two of Medicare's penalties last for life, and both kick in if you delay enrollment without qualifying coverage.

Part B late enrollment penalty

The Part B penalty is 10% of the standard Part B premium for each full 12-month period you could have had Part B but did not. The 2026 standard premium is $202.90 (up from $185.00 in 2025), so each year of delay adds about $20.29 to your monthly premium permanently. The 2026 annual Part B deductible is $283.

Part D late enrollment penalty

The Part D penalty kicks in if you go 63 or more days without Part D or other creditable drug coverage after your IEP. It is 1% of the national base beneficiary premium ($38.99 in 2026) for each full month you went without coverage, rounded to the nearest $0.10. So 14 months without creditable drug coverage adds about $5.50 per month to your Part D premium for life. Because the base premium changes each year, the dollar amount of the penalty is recalculated annually.

Month-by-Month Enrollment Checklist

Start preparing 3 months before your birthday month for the smoothest possible transition.

3 months before your birthday month

• Confirm your Medicare eligibility and IEP dates
• If still working, get a written letter from HR stating whether your employer has 20+ employees and whether drug coverage is creditable
• Create your my Social Security account at SSA.gov
• Apply for Part A (and Part B, if you are not delaying)

2 months before

• Compare Medigap quotes from at least three carriers in your state
• Decide between Original Medicare + Medigap + Part D and Medicare Advantage
• If choosing Medigap, narrow down between Plan G, Plan N, or High-Deductible Plan G
• Review our list of the best Medicare Supplement insurance companies to shortlist carriers

1 month before

• Submit your Medigap application so coverage starts the first day of your birthday month
• Enroll in a standalone Part D plan via Medicare.gov's Plan Finder
• Watch your mailbox for your red, white, and blue Medicare card

Birthday month and after

• Confirm Medicare card, Medigap policy, and Part D plan are all active
• Switch primary care doctors to a Medicare-accepting provider if needed
• Cancel any individual or Marketplace plan effective the day Medicare starts

Common First-Time Enrollment Mistakes

Even careful planners stumble on the same handful of pitfalls.

The single most expensive mistake is delaying Part B without realizing it also delays your Medigap Open Enrollment Period. Because Medigap OEP only starts the month you are both 65 and enrolled in Part B, postponing Part B postpones your one-time underwriting protection. If you later try to buy a Medigap policy after that window closes, you can be denied coverage entirely. Compare top-rated carriers in our roundup of the best Medicare Supplement insurance companies or learn how the AARP/UnitedHealthcare Medigap plans stack up.

If you do end up enrolling in Medicare Advantage first and want to move to Medigap later, our guides on switching from Medicare Advantage to Medigap and Medigap underwriting after leaving Medicare Advantage walk through what to expect.

Frequently Asked Questions

When should I apply for Medicare if I am turning 65?

Apply during the first 3 months of your 7-month Initial Enrollment Period. This timing guarantees your coverage begins on the first day of your birthday month with no gap. Applying early also gives you several weeks to compare and enroll in a Medigap plan and a Part D plan before Medicare starts.

Do I need to enroll in Medicare if I already have employer coverage at 65?

You should still enroll in Part A (it is usually premium-free) unless you contribute to an HSA. Whether to enroll in Part B depends on your employer's size: if 20 or more employees, you can usually delay Part B without penalty using a Special Enrollment Period. If fewer than 20, you almost always need to enroll in Part B at 65 because Medicare becomes your primary coverage.

What happens if I miss my Initial Enrollment Period?

If you miss your IEP and do not qualify for a Special Enrollment Period, you will likely have to wait until the General Enrollment Period (January 1 to March 31) to sign up for Part B, with coverage starting the month after you enroll. You will also owe a permanent late-enrollment penalty of 10% of the 2026 Part B premium ($202.90) for each full 12 months you delayed.

Am I automatically enrolled in Medicare?

Only if you are already receiving Social Security or Railroad Retirement benefits when you turn 65. In that case, you are auto-enrolled in Parts A and B, and your card arrives about 3 months before your coverage starts. Everyone else must actively apply through SSA.gov, by phone, or in person.

When should I buy a Medicare Supplement plan?

Buy your Medigap plan during your 6-month Medigap Open Enrollment Period, which starts the first month you are both 65 and enrolled in Part B. Apply about 1-2 months before your Part B coverage begins so the Medigap policy can take effect on day one of your Medicare coverage. This is the only time most people are guaranteed coverage without medical underwriting. For more on what Medicare does not cover and how Medigap fills those gaps, see our companion guide.