Medicare Part A enrollment windows are tied to when you turn 65 or when you first become may be able to access due to disability or end-stage renal disease

You can sign up for Medicare Part A during three main periods: your Initial Enrollment Period (IEP), which starts three months before the month you turn 65; your General Enrollment Period (GEP), which runs January 1 through March 31 each year; or a Special Enrollment Period (SEP) if you may have access to for one. Most people do not pay a premium for Part A because they or their spouse paid Medicare taxes while working. If you miss your IEP and do not sign up during GEP, you may face a permanent penalty on your premium.

The timing matters because Part A covers hospital stays, skilled nursing facility care, hospice, and home health services. If you delay signing up without a valid reason, you could be responsible for costs that Part A would have covered. Understanding your specific enrollment window helps you avoid gaps in coverage and unexpected bills.

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 are still working and have health insurance through your employer, you may be able to delay Part A enrollment without penalty under certain conditions.
  • The General Enrollment Period (January 1 to March 31) is available every year, but late enrollment penalties explore if you sign up after your IEP ends.
  • You can sign up through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
  • Part A is usually free for people 65 and older who paid Medicare taxes for at least 10 years, either as a worker or spouse.

Your Initial Enrollment Period: the seven-month window

Your Initial Enrollment Period is the easiest time to sign up for Part A because you avoid late penalties and your coverage can start on the first day of your birth month (or the month you turn 65). This seven-month window opens three months before the month you turn 65 and closes three months after.

For example, if you turn 65 in June, your IEP runs from March through September. You can sign up anytime during those seven months. If you sign up in March, April, or May, your coverage begins June 1. If you sign up in June, July, August, or September, your coverage starts the first day of the month after you sign up. This means signing up late in your IEP window delays when your coverage actually begins.

Social Security automatically enrolls most people in Part A and Part B during their IEP if they are already receiving Social Security benefits. If you are not yet receiving benefits, you need to sign up yourself. You can do this online at Medicare.gov, by calling 1-800-MEDICARE, or by visiting your local Social Security office.

When you can delay Part A without penalty

You may be able to delay Part A enrollment past your IEP without facing a permanent penalty if you are still working and covered by your employer's health plan. This is called a Special Enrollment Period based on group health plan coverage. To use this exception, your employer must have at least 20 employees and you must be actively employed.

If you may have access to, you have eight months after your employment ends or your employer coverage stops to sign up for Part A without penalty. You will need to show proof of your employer coverage, such as a pay stub or a letter from your employer's benefits department. This protection applies only if you were actually covered by the employer plan during the time you delayed Medicare — straightforward being may be able to access for the plan is not enough.

If you do not have employer coverage and you miss your IEP, you cannot avoid the late enrollment penalty by waiting for a Special Enrollment Period. The General Enrollment Period is your only other option, and it comes with penalties.

The General Enrollment Period and late penalties

If you miss your Initial Enrollment Period, you can still sign up during the General Enrollment Period, which runs January 1 through March 31 every year. Coverage begins July 1 of that year. However, signing up during GEP instead of your IEP triggers a permanent late enrollment penalty on your Part A premium.

The penalty is 10 percent of the standard Part A premium for each full 12 months you were may be able to access but not enrolled. If you were may be able to access for two years and did not sign up, your penalty would be 20 percent of the standard premium, added to your bill for as long as you have Part A. This penalty does not go away, even if you later move to a different state or change your coverage.

For example, if the standard Part A premium is $100 per month and you were may be able to access for 18 months before signing up, your penalty would be approximately $15 per month (1.5 years × 10 percent), making your total premium $115 per month for life. Because of this permanent cost, it is worth exploring whether you may have access to for a Special Enrollment Period before accepting a late penalty.

How to sign up for Part A

You have three main ways to sign up: online through Medicare.gov, by phone, or in person. The online method is often fastest. Go to Medicare.gov, create an account if you do not already have one, and follow the steps to enroll in Part A. You will need your Social Security number and information about any current health coverage.

To sign up by phone, call 1-800-MEDICARE (1-800-633-4227). Representatives are available Monday through Friday, 8 a.m. to 8 p.m. Eastern time. Have your Social Security number, birth date, and current insurance information ready. If you are deaf or hard of hearing, call the TTY number 1-877-486-2048.

You can also visit your local Social Security office in person. Find the nearest office at ssa.gov or by calling 1-800-772-1213. Bring your Social Security card, proof of citizenship or legal residency (such as a birth certificate or passport), and proof of age. If you are signing up based on disability or end-stage renal disease rather than age, bring documentation of that condition.

Part A coverage and what it includes

Part A covers inpatient hospital care, including semi-private rooms, meals, and standard nursing services. It also covers skilled nursing facility care for up to 100 days per benefit period (after a may have access to hospital stay of at least three days), home health services ordered by your doctor, and hospice care for people with terminal illness.

Part A does not cover long-term custodial care in a nursing home, assisted living, or adult day care. It also does not cover most outpatient services, doctor visits, or prescription drugs — those are covered by Part B and Part D. You pay a deductible for hospital stays and coinsurance for longer stays, but most people do not pay a monthly premium for Part A.

Special situations: disability and end-stage renal disease

You can sign up for Part A before age 65 if you have been receiving Social Security Disability Insurance (SSDI) for 24 months or if you have end-stage renal disease (ESRD) requiring dialysis or a transplant. If you are on SSDI, you become may be able to access for Medicare automatically after 24 months of receiving benefits. Social Security will contact you about enrollment.

If you have ESRD, you can sign up for Part A as soon as your doctor determines you need dialysis or have had a kidney transplant. Your enrollment window is the same as for age-based enrollment: three months before, the month of, and three months after the month your condition qualifies you. Contact Social Security or Medicare to start the process.

People with amyotrophic lateral sclerosis (ALS) have a different rule: they become may be able to access for Medicare when ready upon approval for SSDI, without waiting 24 months. If you have ALS, ask Social Security about when ready enrollment.

What to ask your doctor and when to seek help

Before your enrollment period begins, ask your doctor whether you have any ongoing medical needs that Part A should cover — for instance, if you might need skilled nursing care after surgery or if you have a condition that could lead to hospitalization. This helps you understand what Part A will do for you and whether you need additional coverage like Medigap or Medicare Advantage.

If you are unsure whether you may have access to for a Special Enrollment Period based on employer coverage, ask your employer's benefits department for written confirmation of your coverage dates and the number of employees. Bring this to Social Security or Medicare when you sign up. If you miss your IEP and are unsure whether you owe a late penalty, contact Medicare directly before signing up during GEP — they can review your specific situation.

If you are approaching 65 and have questions about your enrollment window, call 1-800-MEDICARE at least one month before your birthday. Representatives can confirm your IEP dates, explain your options, and answer questions about coverage. If you are on SSDI or have ESRD, ask Social Security directly about your enrollment timeline.

Frequently Asked Questions

What happens if I turn 65 while still working?

You can delay Part A enrollment if your employer has at least 20 employees and you are actively working and covered by their health plan. You have eight months after you stop working or lose that coverage to sign up without penalty. If you do not have employer coverage, you should still sign up during your IEP to avoid late penalties.

Do I have to sign up for Part B at the same time as Part A?

No. Part A and Part B are separate. You can sign up for Part A during your IEP and delay Part B if you have employer coverage. However, if you delay Part B without a valid reason, you will owe a late enrollment penalty on Part B premiums. Ask Medicare or Social Security about your specific situation.

Can I change my mind after I sign up for Part A?

Yes, but only during specific windows. If you sign up during your IEP and change your mind, you can request to be disenrolled, but this is rarely recommended because you lose coverage. If you want to make changes to your coverage (such as adding Part B or switching to Medicare Advantage), you can do so during the Annual Enrollment Period (October 15 to December 7) or during a Special Enrollment Period if you may have access to.

Will I owe back premiums if I sign up late?

Part A is usually free, so you will not owe back premiums. However, if you do owe a Part A premium (because you did not pay Medicare taxes for 10 years), you may owe back premiums for the months you were may be able to access but not enrolled. A late enrollment penalty will be added to your monthly premium going forward.

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

You must be a U.S. citizen or legal permanent resident (green card holder) for at least five years to sign up for Part A. If you are a legal permanent resident, bring your green card and proof of residency when you enroll. If you are not yet a permanent resident, contact Social Security to discuss your options.