You can file for Medicare starting three months before the month you turn 65

Medicare enrollment opens during a seven-month window: three months before you turn 65, the month you turn 65, and three months after. If you sign up during this window, your coverage begins on the first day of the month you turn 65. If you miss this window, you can still enroll, but your coverage will start later and you may pay a permanent penalty on your premiums.

You do not have to wait until your 65th birthday to file. You can start the process as soon as you are three months away from that date. For example, if you turn 65 in September, you can file starting in June. Filing early gives you time to choose your plan and understand your coverage before it begins.

The rules are different if you are still working and have health insurance through your job. If your employer has 20 or more employees, you can delay Medicare enrollment without penalty as long as you stay covered by that employer plan. Once you leave that job or lose that coverage, you have eight months to enroll without penalty.

Key Takeaways

  • Your initial enrollment window is seven months long: three months before you turn 65, the month you turn 65, and three months after.
  • If you enroll during this window, coverage starts on the first of the month you turn 65; if you enroll after, coverage starts the first of the following month.
  • Missing your initial window triggers a permanent 10 percent penalty on Part B premiums for each year you delayed, unless you had employer coverage.
  • If you are covered by an employer plan with 20 or more employees, you can delay Medicare without penalty and have eight months to enroll after leaving that job.
  • You file through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

How the Initial Enrollment Window Works

Your Initial Enrollment Period is a one-time seven-month window. It starts three months before the month you turn 65 and ends three months after. During this window, you can enroll in Medicare Part A (hospital insurance) and Part B (medical insurance) without waiting and without penalty.

The month you turn 65 is the middle month of this window. If you turn 65 on any day in that month—the first or the last—your enrollment window is the same. For example, whether you turn 65 on January 5 or January 31, your window runs from October of the previous year through March of that year.

Timing matters because your coverage start date depends on when you enroll. If you file during the three months before your birthday month, coverage begins the first of the month you turn 65. If you file during your birthday month or the three months after, coverage begins the first of the month after you enroll. This delay is why filing early is usually the better choice.

What Happens If You Miss Your Initial Window

If you do not enroll during your Initial Enrollment Period, you can still file for Medicare later. However, you will face a permanent penalty on your Part B premiums. The penalty is 10 percent of the standard Part B premium for each full year you delayed enrollment after your Initial Enrollment Period ended.

This penalty stays with you for life. If you delayed for three years, you pay 30 percent more than the standard premium every month for the rest of your life. The only way to avoid this penalty is to have had creditable coverage—usually employer insurance or TRICARE—during the time you were not enrolled in Medicare.

You can enroll in Medicare during the General Enrollment Period, which runs from January 1 to March 31 each year. Coverage begins July 1 of that year. This is much slower than your Initial Enrollment Period, which is why missing your window is costly.

Special Rules If You Are Still Working

If you are still employed and your employer has 20 or more employees, you can delay Medicare Part B without penalty. Your employer health insurance is considered creditable coverage, which means it counts as continuous insurance. You do not need to enroll in Medicare while you are covered by that plan.

Once you leave your job or lose your employer coverage, you have eight months to enroll in Medicare without penalty. This eight-month window is called your Special Enrollment Period. You must enroll within this period to avoid the permanent 10 percent penalty. You will need to show proof that you had employer coverage—usually a letter from your employer's benefits department stating your coverage dates and that the plan met Medicare's standards.

If your employer has fewer than 20 employees, Medicare is your primary insurance, and you should enroll during your Initial Enrollment Period even if you are still working. Delaying in this case will trigger the penalty.

How to File for Medicare

You can file for Medicare through three channels: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. The online option is usually the fastest. You will need your Social Security number, proof of citizenship or legal residency, and information about any current health coverage.

If you file online, you can complete the process in about 15 minutes. If you file by phone, a representative will walk you through the same questions. If you file in person, bring your Social Security card, birth certificate, and proof of citizenship (passport, naturalization papers, or state ID). Processing typically takes two to four weeks.

When you file, you will also choose your coverage. Part A (hospital insurance) is usually free if you or your spouse paid Medicare taxes for at least 10 years. Part B (medical insurance) costs a monthly premium that varies by income. You will also choose whether to enroll in a Medigap plan (supplemental insurance) or a Medicare Advantage plan (an alternative to Original Medicare).

Medicare Enrollment for People Under 65

Most people file for Medicare at 65, but some people under 65 are also covered. If you have received Social Security Disability Insurance (SSDI) for 24 months, you become covered by Medicare automatically. You do not need to file; Medicare begins the 25th month after your SSDI approval.

If you have End-Stage Renal Disease (ESRD) or Amyotrophic Lateral Sclerosis (ALS), you may also be covered by Medicare regardless of age. The rules for these conditions are complex and depend on your specific situation. Contact Social Security or Medicare directly to understand your coverage.

Frequently Asked Questions

What if I turn 65 and do not want Medicare yet?

You can decline Medicare Part B if you have employer coverage, but you should still enroll in Part A (hospital insurance) to avoid penalties later. If you decline Part B while working, you have eight months after leaving your job to enroll without penalty. If you decline without creditable coverage, you will pay the 10 percent penalty for each year you delayed.

Can I change my Medicare plan after I enroll?

Yes, but only during specific windows. You can change plans during the Annual Enrollment Period (October 15 to December 7 each year), and your new coverage begins January 1. If you have a may have access to life event—such as losing employer coverage, moving, or getting married—you may have a Special Enrollment Period outside the annual window.

Do I need to file for Social Security before I file for Medicare?

No. Medicare and Social Security are separate programs. You can file for Medicare without filing for Social Security benefits. However, if you are 62 or older and want Social Security retirement benefits, you will file for that separately. Some people delay Social Security to get a higher benefit while enrolling in Medicare at 65.

What if I am not a U.S. citizen?

You must be a U.S. citizen or a lawful permanent resident (green card holder) who has lived in the United States for at least five years to be covered by Medicare. If you are a lawful permanent resident, you will need to show your green card and proof of your five-year residency when you file.

Can I file for my spouse's Medicare?

No. Each person files for their own Medicare coverage. Your spouse can file during their own Initial Enrollment Period, which is based on their birthday. If your spouse is not yet 65 but is covered by your employer plan, they can delay enrollment and file later without penalty.