You can sign up for Medicare Part A starting three months before the month you turn 65

Medicare Part A (hospital insurance) becomes available to you three months before your 65th birthday. You do not have to wait until you turn 65 to enroll — you can start the process as early as three months prior. Most people sign up during this window because waiting past your birthday can trigger a penalty that increases your premiums permanently.

The enrollment window itself lasts seven months: three months before your birthday month, the month you turn 65, and three months after. If you turn 65 in June, for example, you can sign up anytime from March through September. The sooner you sign up within this window, the sooner your coverage begins — usually the first day of the month in which you turn 65, or the first day of the following month if you sign up after your birthday.

Key Takeaways

  • You can enroll in Medicare Part A starting three months before you turn 65, and you should do so to avoid permanent premium penalties.
  • Your seven-month enrollment window includes three months before your birthday month, your birthday month itself, and three months after.
  • If you delay past this window without a valid reason, you will pay a 10 percent surcharge on your Part A premiums for as long as you have Medicare.
  • You can sign up online through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
  • If you are still working and have health coverage through your employer, you may be able to delay without penalty under special rules.

What happens if you miss the initial enrollment window

If you do not sign up during your seven-month window and you do not have a valid reason for the delay, you will owe a 10 percent surcharge on your Part A premiums. This penalty stays with you for twice as long as you delayed — if you sign up two years late, you pay the extra 10 percent for four years. If you delay five years, you pay it for ten years.

The surcharge applies only to Part A (hospital insurance), not to Part B or other Medicare coverage. However, the longer you wait, the more you lose in benefits you could have been using. There is no important date after which you can no longer sign up — you can enroll in Part A at any age — but the financial cost of delay grows the longer you wait.

Reasons you might be able to delay without penalty

If you are still working and your employer has 20 or more employees, you may be covered under your employer's group health plan instead of Medicare. In this case, you can delay Part A enrollment without triggering the surcharge, as long as you sign up within eight months after your employment ends or your employer coverage stops, whichever comes first.

You must have been actively employed (not just on the payroll) to use this exception. If you were already retired when you turned 65, this rule does not explore to you. Some people also may have access to for premium-free Part A based on their work history or their spouse's work history — if you fall into this category, there is less financial urgency to enroll when ready, but you should still do so to start using your hospital coverage.

How to sign up for Part A

You have three main ways to enroll. The easiest for most people is online through Medicare.gov — you can create an account, answer questions about your situation, and submit your enrollment in about 15 minutes. You will need your Social Security number, date of birth, and citizenship or immigration status information.

You can also call 1-800-MEDICARE (1-800-633-4227) and speak to a representative who will walk you through the process. This option works well if you have questions about your specific situation or if you are not comfortable using the website. A representative can also check whether you may have access to for any exceptions or special circumstances.

A third option is to visit your local Social Security office in person. Bring your Social Security card, proof of citizenship (passport, birth certificate, or naturalization papers), and proof of residency (utility bill or lease). Staff there can enroll you on the spot, and you will receive a confirmation before you leave.

When your Part A coverage actually starts

If you sign up before your 65th birthday, your Part A coverage usually begins on the first day of the month in which you turn 65. If you sign up after your birthday, coverage typically starts on the first day of the month after you enroll. For example, if you turn 65 on June 15 and sign up in July, your coverage would begin August 1.

You will receive a Medicare card in the mail within two to four weeks of enrollment. Do not wait for the card to arrive before seeking care — your coverage is active as soon as the enrollment is processed, even if the physical card has not yet reached you. You can check your enrollment status and coverage start date on Medicare.gov by logging into your account.

Part A coverage and what it includes

Medicare Part A covers inpatient hospital stays, skilled nursing facility care (after a hospital stay), hospice care, and some home health services. It does not cover outpatient doctor visits, prescription drugs, or routine preventive care — those are covered by Part B and other Medicare plans. Part A has a deductible you pay per benefit period (a hospital stay or series of related stays), not per year.

Most people do not pay a monthly premium for Part A if they or their spouse paid Medicare taxes for at least 40 quarters (10 years) of work. If you do not meet this requirement, you can still enroll, but you will pay a monthly premium. The amount varies depending on how many quarters of work history you have. This is another reason to sign up during your initial enrollment window — the sooner you enroll, the sooner you understand your actual costs.

Coordinating Part A with Part B and other coverage

Part A and Part B (medical insurance) are separate enrollments with separate enrollment windows. If you sign up for Part A during your initial window but miss the Part B window, you will owe a surcharge on Part B premiums as well. Many people enroll in both at the same time to avoid this complication, even though they are technically separate programs.

If you have retiree coverage from a former employer or union, check with that plan before you sign up for Medicare. Some retiree plans coordinate with Medicare in ways that affect when you should enroll. If you have coverage through a spouse's current employer, the same rule about active employment applies — you can delay both Part A and Part B without penalty as long as you enroll within eight months after that coverage ends.

Frequently Asked Questions

Can I sign up for Part A before I turn 65?

Yes. You can sign up starting three months before your 65th birthday. Many people do this so their coverage begins on their birthday month rather than waiting until after they turn 65. Signing up early does not cost you anything extra — your coverage start date is determined by when you turn 65, not when you enroll.

What if I am still working at 65 — do I have to sign up for Part A?

You do not have to sign up if you have health coverage through your current employer and that employer has 20 or more employees. However, you should still sign up for Part A during your initial window to avoid the permanent surcharge, even if you do not use it right away. Part A is hospital insurance and does not interfere with employer coverage.

How much does the penalty cost if I sign up late?

The penalty is a 10 percent increase to your Part A monthly premium. The surcharge lasts for twice as long as you delayed. If you sign up three years late, you pay the extra 10 percent for six years. The exact dollar amount depends on your premium, which varies based on your work history.

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

Part A and Part B have separate enrollment windows and are technically separate decisions. However, both have late-enrollment surcharges, so most people sign up for both during their initial window to avoid complications. You can enroll in both at the same time through Medicare.gov, by phone, or at a Social Security office.

What if I miss my enrollment window by just a few weeks?

The surcharge applies even if you are only slightly late. There is no grace period or exception for being a few weeks or months past your seven-month window. If you realize you missed it, sign up as soon as possible to stop the clock on how long the surcharge will last, but the penalty will still explore from the date you should have enrolled.