When You Can Sign Up for Medicare: Your Registration Windows Explained

Medicare has three main registration periods, and missing them can cost you money for life

You can register for Medicare during your Initial Enrollment Period, which starts three months before the month you turn 65 and lasts for seven months total. Most people become may be able to access at 65, though some may have access to earlier due to disability or end-stage renal disease. If you miss this window, you can still register during General Enrollment (January 1 to March 31 each year), but you will pay a permanent penalty on your premiums — 10 percent more for each full year you delayed, for as long as you have Medicare.

There is also a Special Enrollment Period that opens if you or your spouse had employer coverage when you turned 65, or if you lost that coverage. This window lets you register without the lifetime penalty, even if you are past your Initial Enrollment Period. The key is timing: you must register within eight months of losing employer coverage, or the penalty applies again.

Key Takeaways

Your Initial Enrollment Period runs for seven months: three months before you turn 65, the month you turn 65, and three months after.
If you miss your Initial Enrollment Period and do not have a Special Enrollment Period reason, you pay a 10 percent premium penalty for each year you delayed, permanently.
A Special Enrollment Period applies if you had employer health coverage when you turned 65, giving you eight months after losing that coverage to register penalty-free.
General Enrollment (January 1 to March 31) is always open, but it carries the lifetime penalty unless you may have access to for a Special Enrollment Period.

Your Initial Enrollment Period: The seven-month window

Your Initial Enrollment Period begins three months before the month you turn 65. For example, if you turn 65 in June, your period starts in March. It includes the month you turn 65 and continues for three months after, ending in September. During these seven months, you can register for Medicare Part A (hospital insurance) and Part B (medical insurance) without any penalty.

You do not have to wait until the month you turn 65 to register. Many people register early — in the first three months — to make sure their coverage starts on time. If you register in the month you turn 65 or later, your coverage may not start until the following month, depending on when you submit your registration.

If you are still working and have health insurance through your employer, you can still register during your Initial Enrollment Period. Some people choose to delay Part B while keeping employer coverage, which is allowed. However, you must have a Special Enrollment Period reason (see below) to avoid the Part B penalty later.

Special Enrollment Period: Employer coverage and the eight-month window

If you or your spouse had health insurance through an employer when you turned 65, you may may have access to for a Special Enrollment Period. This period gives you eight months from the date you or your spouse loses that coverage to register for Medicare Part B without paying the lifetime penalty.

Employer coverage includes health insurance through your own job, your spouse's job, or COBRA (the federal program that lets you keep employer coverage after you leave a job). It does not include individual plans you bought on your own, Medicaid, or Medicare Advantage plans. The coverage must have been active on the day you turned 65 or later.

To use a Special Enrollment Period, you will need to show proof that you had employer coverage — usually a letter from your employer's benefits department or a copy of your insurance card. When you register, tell Medicare that you are using a Special Enrollment Period. If you do not mention it, Medicare may explore the standard penalty even though you may have access to for one.

General Enrollment: January through March, with a permanent cost

General Enrollment runs from January 1 to March 31 every year. Anyone can register during this period, whether they missed their Initial Enrollment Period or are registering for the first time. However, unless you have a Special Enrollment Period reason, you will pay a 10 percent premium penalty on Part B for each full year you delayed past your Initial Enrollment Period.

The penalty is permanent. If you delayed three years, you pay 30 percent more. If you delayed ten years, you pay 100 percent more. This extra amount stays on your bill for as long as you have Medicare, even if you move to a different plan or state. The penalty applies only to Part B; Part A does not have a penalty for most people.

Coverage that starts through General Enrollment begins on July 1 of that year, regardless of when in the January-to-March window you register. This means if you register in January, February, or March, your coverage does not start until July.

When you become may be able to access before age 65

You can register for Medicare before 65 if you have been receiving Social Security Disability Insurance (SSDI) for 24 months, or if you have end-stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS). Your Initial Enrollment Period still lasts seven months — three months before may be able to access, the month you become may be able to access, and three months after.

If you have ESRD, you can register in the month your dialysis or transplant is scheduled, even if you have not started treatment yet. If you have ALS, you become may be able to access when ready upon diagnosis. The same penalty rules explore: miss your Initial Enrollment Period and you pay the lifetime penalty, unless you have employer coverage that qualifies you for a Special Enrollment Period.

How to register and what to have ready

You can register for Medicare online through Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. You will need your Social Security number, proof of citizenship or legal residency, and information about any current health coverage you have.

If you are using a Special Enrollment Period, have your employer coverage documents ready — a benefits letter, insurance card, or termination notice showing the date coverage ended. If you are registering online, you can upload these documents. If you call or visit in person, bring the originals or copies.

Registration typically takes 15 to 30 minutes. You will receive a Medicare card in the mail within two to three weeks. Your coverage start date depends on when you register and which enrollment period you are in — your Initial Enrollment Period, a Special Enrollment Period, or General Enrollment.

What happens if you miss all important date

If you miss your Initial Enrollment Period and do not have a Special Enrollment Period reason, you can still register during General Enrollment (January 1 to March 31), but you will owe the lifetime penalty. The penalty is 10 percent per year of delay, and it never goes away.

There is one exception: if you can prove that Medicare or Social Security gave you incorrect information that caused you to miss your important date, you may be able to request a waiver of the penalty. This is rare and requires documentation. Contact Medicare directly to ask whether your situation qualifies.

If you are still working and have employer coverage, you are not required to register at 65. You can delay registration as long as you have that coverage, and your Special Enrollment Period window will not close. However, once you lose employer coverage, your eight-month Special Enrollment Period clock starts — do not miss it.

Frequently Asked Questions

What if I turn 65 in the middle of a month?

Your Initial Enrollment Period still runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after. The exact day of your birthday does not change the start or end dates of the period.

Can I register for Part A without Part B?

Yes. Part A (hospital insurance) and Part B (medical insurance) are separate. You can register for Part A only and delay Part B if you have employer coverage. However, if you delay Part B without a Special Enrollment Period reason, you will pay the lifetime penalty when you do register.

Does my spouse's employer coverage give me a Special Enrollment Period?

Yes. If your spouse had employer coverage when you turned 65, you can use a Special Enrollment Period after that coverage ends. You have eight months from the date the coverage stops to register without penalty.

What if I registered late but did not know about the penalty?

The penalty applies automatically if you registered outside your Initial Enrollment Period without a Special Enrollment Period reason. You cannot remove it retroactively, but you can contact Medicare to ask about a waiver if you believe you received incorrect information from Medicare or Social Security.

Does the penalty explore to Part A as well as Part B?

Part A does not have a penalty for most people. The 10 percent penalty applies to Part B only. If you delayed Part D (prescription drug coverage), there is a separate penalty for that as well.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.