You must sign up for Medicare at 65, but the exact important date depends on your work and insurance history

If you are turning 65 or already past 65, you need to understand when Medicare enrollment is required and what happens if you miss the window. The rule is straightforward: you must sign up during your Initial Enrollment Period, which runs for seven months centered on your 65th birthday — three months before, the month of, and three months after. If you do not sign up during this window and you do not have a valid reason for the delay, you will face permanent penalties on your premiums.

However, there is an important exception. If you are still working and covered by your employer's health plan, or if your spouse is still working and you are on their plan, you may not need to sign up at 65. You can delay enrollment without penalty as long as you stay covered by that employer plan. The moment you or your spouse leaves that job, you have eight months to sign up for Medicare before penalties kick in.

The same eight-month grace period applies if you have coverage through COBRA (the temporary health plan you can keep after leaving a job) or through a union health plan. Once that coverage ends, your clock starts ticking.

Key Takeaways

  • Your Initial Enrollment Period is seven months long — three months before your 65th birthday, your birth month, and three months after — and you should sign up during this time unless you have active employer coverage.
  • If you are covered by your employer's health plan at 65, you can delay Medicare enrollment without penalty, but you must sign up within eight months of leaving that job.
  • Missing your enrollment window without a valid reason results in permanent premium increases that last for the rest of your life.
  • You sign up through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
  • Part A (hospital insurance) is usually free if you or your spouse paid Medicare taxes for at least 10 years, but Part B (doctor visits) has a monthly premium that increases if you delay.

What happens if you miss your enrollment important date

If you do not sign up during your Initial Enrollment Period and you do not have employer coverage or another valid reason for the delay, Medicare adds a permanent penalty to your Part B premium. The penalty is 10 percent of the standard Part B premium for each full year you were may be able to access but not enrolled. If you were may be able to access for three years and did not sign up, your premium goes up 30 percent — and that increase stays with you for life, even after you finally enroll.

Part D (prescription drug coverage) has a similar penalty. If you go 63 days or longer without prescription coverage and you do not have a valid reason, you pay an extra amount each month when you finally join a plan. This penalty also lasts for the rest of your coverage.

The valid reasons that let you delay without penalty are limited. They include active employer coverage (yours or your spouse's), COBRA, union health plans, and certain government employee plans. Medicaid alone does not count as a valid reason to delay Part B. If you are on Medicaid and turn 65, you still need to sign up for Medicare Part B during your Initial Enrollment Period or face the penalty.

How to sign up and what you will need

You can sign up for Medicare three ways: online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. Online is usually fastest — you can complete the process in 15 to 20 minutes if you have the right documents ready.

Before you start, gather your Social Security number, proof of citizenship or legal residency (your birth certificate, passport, or naturalization papers), and proof of residence (a recent utility bill or lease). If you are signing up for Part B, you will also need information about any current health coverage you have, including your employer's name and the dates you were covered.

The Social Security Administration handles enrollment for Parts A and B. If you want to add Part D (prescription drugs) or a Medicare Advantage plan (Part C), you can do that at the same time, or you can add them later during the annual open enrollment period from October 15 to December 7 each year.

When you can delay without penalty

The most common reason to delay is active employer coverage. If you are still working at 65 and your employer offers health insurance, you do not have to sign up for Medicare. You can stay on your employer plan and sign up for Medicare later. The same applies if you are retired but your spouse is still working and you are covered under their plan.

When you leave that job or your spouse retires, you have eight months to sign up for Medicare. This eight-month window is called your Special Enrollment Period. If you sign up within this window, you will not face any penalties, even though you are past your Initial Enrollment Period.

If you are on COBRA (the temporary coverage you can keep for up to 18 months after leaving a job), the same rule applies — you have eight months from the date COBRA ends to sign up for Medicare without penalty. If you are in a union health plan or a retiree health plan from a former employer, the eight-month grace period also applies.

Part A versus Part B: which parts you need

Medicare has four parts, and you need to understand which ones you are required to take. Part A covers hospital stays, skilled nursing care, hospice, and some home health services. Most people do not pay a premium for Part A if they or their spouse paid Medicare taxes for at least 10 years while working. If you do not meet that requirement, you can still buy Part A, but it costs money.

Part B covers doctor visits, outpatient care, lab tests, and some preventive services. Part B has a monthly premium that changes each year. In 2024, the standard premium is $164.90 per month, but it varies based on your income. If you delay signing up for Part B past your Initial Enrollment Period without a valid reason, your premium increases by 10 percent for each year you were may be able to access but not enrolled.

Part D (prescription drug coverage) and Part C (Medicare Advantage, an alternative to Original Medicare) are optional. You do not have to take either one, but if you go without Part D for more than 63 days and you do not have other prescription coverage, you will face a permanent penalty when you finally join.

Income-based premiums and extra help

Your Part B and Part D premiums may be higher if your income is above a certain threshold. Medicare uses your income from two years ago to calculate this, so if your income was high in 2022, your 2024 premiums may be higher. If your income drops — because you retire, for example — you can ask Medicare to recalculate your premiums based on your current income.

If your income is low, you may be able to get help paying your premiums through a program called Extra Help (for Part D) or Medicaid (for Part B and Part A). These programs are run by your state, and the income limits vary. You can learn about your state's programs by calling 1-800-MEDICARE or visiting Medicare.gov.

What to do if you missed your important date

If you are past your Initial Enrollment Period and you do not have employer coverage, you can still sign up for Medicare, but you will face penalties unless you have a valid reason for the delay. The first step is to contact Medicare and explain your situation. Some reasons — like losing employer coverage, moving to a new state, or a change in your Medicaid status — may may have access to you for a Special Enrollment Period, which waives the penalty.

Call 1-800-MEDICARE and describe what happened. Be specific about dates: when you turned 65, when you lost coverage, when you realized you needed to sign up. Medicare staff will tell you whether you may have access to for a penalty waiver. If you do not may have access to, you can still enroll, but your premiums will be higher. It is better to sign up late than not to sign up at all — you will still get coverage, and you can appeal the penalty later if your circumstances change.

Frequently Asked Questions

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

No, not if your employer offers health insurance and you are covered by it. You can delay signing up for Medicare as long as you have active employer coverage. Once you leave that job, you have eight months to sign up without penalty. If you do not sign up within those eight months, you will face permanent premium increases.

What if I am on Medicaid — do I still need to sign up for Medicare at 65?

Yes. Medicaid does not count as a valid reason to delay Medicare enrollment. You must sign up for Medicare during your Initial Enrollment Period (seven months centered on your 65th birthday) or face penalties. You can have both Medicaid and Medicare at the same time — this is called "dual may be able to access."

Can I sign up for Medicare after 65 without a penalty?

Only if you have a valid reason, such as active employer coverage, COBRA, a union health plan, or a may have access to life event. If you do not have one of these reasons and you miss your Initial Enrollment Period, you will pay a permanent penalty on your Part B premium. The penalty is 10 percent of the standard premium for each full year you were may be able to access but not enrolled.

What if I do not want Part B?

You can decline Part B during your Initial Enrollment Period, but if you change your mind later and do not have a valid reason for the delay, you will face a permanent premium penalty. The only way to avoid the penalty is to have had employer coverage that counted as a valid reason to delay. If you are unsure, it is safer to enroll in Part B during your Initial Enrollment Period — you can always drop it later if you do not need it.

How do I know if my employer coverage counts as a valid reason to delay Medicare?

Your employer's human resources or benefits department can tell you whether your plan qualifies. Generally, any health insurance offered by your current employer counts, as does coverage through your spouse's employer, COBRA, a union, or a retiree health plan. Call your benefits office and ask whether your coverage is "creditable" for Medicare purposes — that is the term they use.