Medicare Enrollment: When and How to Sign Up for Medicare

Knowing when to sign up for Medicare is important because enrolling at the wrong time can lead to gaps in coverage or, in some situations, late-enrollment penalties.

Quick answer: For most people who become eligible for Medicare at age 65, the Initial Enrollment Period lasts seven months. It begins three months before the month you turn 65, includes your birthday month and ends three months after your birthday month. However, people with qualifying health coverage based on current employment may have different enrollment options.

For a broader overview of Medicare coverage, costs, plan options and enrollment, see our complete guide to Medicare in California.

When Can You First Sign Up for Medicare?

Most people first become eligible for Medicare around age 65.

Your Medicare Initial Enrollment Period generally lasts seven months:

• Three months before the month you turn 65
• The month you turn 65
• Three months after the month you turn 65

For example, if your birthday is in July, your Initial Enrollment Period generally runs from April through October.

There are special timing rules if your birthday falls on the first day of a month, so it is important to confirm your individual enrollment dates.

Do You Automatically Get Medicare at 65?

Some people are automatically enrolled in Medicare, while others need to sign up.

If you are already receiving certain Social Security or Railroad Retirement Board benefits before becoming eligible for Medicare, you may be automatically enrolled in Medicare Part A and Part B.

If you are not automatically enrolled, you generally need to sign up for Medicare yourself.

Do not assume that simply turning 65 automatically activates Medicare coverage. Check your enrollment status as you approach eligibility.

How Do You Sign Up for Medicare?

Enrollment in Medicare Part A and Part B is generally handled through the Social Security Administration rather than through a private insurance company.

You can apply for Medicare through Social Security. Depending on your circumstances, you may be able to complete the enrollment process online or submit the appropriate enrollment forms.

If you already have Part A and are enrolling in Part B after having qualifying employer coverage, additional documentation may be required to show that you had job-based health insurance.

What Are Medicare Part A and Part B?

Medicare Part A is commonly called hospital insurance and primarily helps cover inpatient hospital care, skilled nursing facility care when Medicare requirements are met, hospice care and certain home health services.

Medicare Part B is commonly called medical insurance and helps cover doctors, outpatient care, preventive services, durable medical equipment and other medically necessary services.

Together, Part A and Part B make up Original Medicare.

For a more detailed explanation, see our guide to Medicare Part A vs. Part B.

When Does Medicare Coverage Start?

Your Medicare start date depends on when you enroll and your individual circumstances.

If you enroll during the first three months of your Initial Enrollment Period, Medicare coverage generally begins the first day of the month you turn 65. Special rules apply if your birthday is on the first day of the month.

If you enroll during your birthday month or during the final three months of your Initial Enrollment Period, coverage generally begins the first day of the month after you enroll.

Because your enrollment date can affect when coverage begins, waiting until the end of your Initial Enrollment Period can potentially create a gap in health coverage.

Can You Delay Medicare Part B?

Some people can delay Medicare Part B without a late-enrollment penalty because they have qualifying group health coverage based on current employment.

This may apply if you or your spouse are still actively working and you are covered by a qualifying employer group health plan.

However, having health insurance does not automatically mean that delaying Part B is appropriate.

The type of coverage, whether it is based on current employment and how the employer plan coordinates with Medicare can all matter.

If you plan to work beyond age 65, see our guide to Working Past 65: Do You Need to Sign Up for Medicare?.

Does Employer Size Matter When You Turn 65?

Employer size can affect how employer health insurance coordinates with Medicare.

If you are approaching 65 while covered through an employer, ask the employer or benefits administrator how the group health plan works with Medicare and whether Medicare is expected to pay first or second.

Medicare specifically advises people with job-based coverage to check with the employer providing their health insurance about whether they need to enroll in Part A and Part B when they turn 65.

Do not assume that employer coverage alone means you should automatically delay Medicare.

What Is a Medicare Special Enrollment Period?

A Special Enrollment Period, or SEP, can allow certain people to enroll in Medicare outside their Initial Enrollment Period without waiting for the next General Enrollment Period.

One important example involves people who delayed Part B because they had qualifying group health coverage based on current employment.

In this situation, you may generally be able to enroll in Part B while you are still covered by the qualifying group health plan or during an eight-month Special Enrollment Period after the employment or qualifying coverage ends, whichever happens first.

Other circumstances can also create Special Enrollment Periods, and the rules and deadlines depend on the specific situation.

Does COBRA Give You More Time to Enroll in Medicare?

COBRA should not be treated the same as health insurance based on current employment for Medicare Part B enrollment purposes.

If employment ends, the eight-month Part B Special Enrollment Period generally begins even if you elect COBRA coverage.

Choosing COBRA does not extend that Medicare enrollment window.

This is an important distinction because waiting until COBRA ends before enrolling in Medicare can potentially result in a coverage gap or late-enrollment penalty.

What About Retiree Health Coverage?

Retiree health insurance can also work differently from coverage based on current employment.

Some retiree plans are designed to coordinate with Medicare and may require you to have Medicare Part A and Part B for the retiree plan to provide its intended coverage.

If you have retiree coverage, review the plan's Medicare requirements rather than assuming it gives you the same enrollment protections as active employer coverage.

What Happens if You Miss Your Initial Enrollment Period?

If you miss your Initial Enrollment Period and do not qualify for a Special Enrollment Period, you may need to use Medicare's General Enrollment Period to enroll in Part B.

The General Enrollment Period runs from January 1 through March 31 each year.

Depending on your circumstances, enrolling late can also result in a Part B late-enrollment penalty.

What Is the Medicare Part B Late-Enrollment Penalty?

If you do not enroll in Part B when you are first eligible and do not qualify for an applicable Special Enrollment Period, you may have to pay a late-enrollment penalty.

The penalty can increase the amount you pay for Part B and may continue for as long as you have Part B.

That is why it is important to understand whether your existing coverage actually allows you to delay Part B before deciding not to enroll.

When Should You Enroll in Medicare if You're Retiring?

If you delayed Medicare because you had qualifying coverage through current employment and are preparing to retire, begin reviewing your Medicare enrollment before your employer coverage ends.

Medicare advises people who want Medicare coverage to begin when their job-based insurance ends to enroll before that employer coverage terminates.

Planning ahead can help reduce the risk of a gap between employer coverage and Medicare.

What Happens After You Enroll in Part A and Part B?

Once you have Medicare Part A and Part B, you will need to understand how you want to receive your Medicare coverage.

The two primary approaches are:

• Original Medicare: Part A and Part B administered through the federal Medicare program
• Medicare Advantage: An alternative way to receive your Medicare benefits through a Medicare-approved private insurance company

People who remain with Original Medicare may also consider separate Part D prescription drug coverage and, if eligible, Medicare Supplement Insurance.

See our guide to Original Medicare vs. Medicare Advantage to understand how these two approaches differ.

When Can You Enroll in Medicare Part D?

Medicare Part D provides prescription drug coverage.

When you first become eligible for Medicare, you generally have an opportunity to enroll in Part D coverage. If you go without Medicare drug coverage or other creditable prescription drug coverage for too long, a late-enrollment penalty may apply when you enroll later.

Learn more in our guide to Medicare Part D and prescription drug coverage.

Medicare Enrollment Checklist

As you approach Medicare eligibility, consider reviewing the following:

• Confirm your Medicare eligibility date
• Determine whether you will be automatically enrolled
• Identify your Initial Enrollment Period
• Review any employer or spouse's employer health coverage
• Ask how that coverage coordinates with Medicare
• Determine whether delaying Part B is permitted in your situation
• Review your prescription drug coverage
• Understand when your current health coverage will end
• Allow enough time to complete Medicare enrollment before you need coverage

Frequently Asked Questions

What is the Medicare Initial Enrollment Period?

For most people becoming eligible at age 65, the Initial Enrollment Period is a seven-month period beginning three months before the month you turn 65 and ending three months after your birthday month.

Do I have to sign up for Medicare at 65 if I'm still working?

Not necessarily. Some people with qualifying group health coverage based on current employment may be able to delay Part B without a late-enrollment penalty. The rules depend on your coverage and circumstances.

Can I sign up for Medicare before I turn 65?

If you are becoming eligible based on age, your Initial Enrollment Period generally begins three months before the month you turn 65. Some people qualify for Medicare before age 65 because of disability or certain medical conditions.

Can I wait until COBRA ends to enroll in Medicare Part B?

Do not assume COBRA extends your Medicare Part B enrollment period. The eight-month Special Enrollment Period associated with qualifying current-employment coverage generally begins when the employment or qualifying coverage ends, even if you choose COBRA.

Where do I sign up for Medicare Part A and Part B?

Medicare Part A and Part B enrollment is generally handled through the Social Security Administration. Official enrollment information is available through Medicare.gov and SSA.gov.

What should I do after enrolling in Medicare?

After enrolling in Part A and Part B, learn how Original Medicare and Medicare Advantage work, review prescription drug coverage and understand the enrollment periods that apply to any additional coverage you are considering.

This article is for general educational and informational purposes. Medicare eligibility, enrollment periods and coverage rules can vary based on individual circumstances and may change over time. For official Medicare enrollment information, visit Medicare.gov, SSA.gov or call 1-800-MEDICARE.