When to Start Medicare: Age, Work Status, and Enrollment Deadlines

You become may be able to access for Medicare at 65, but the exact month you should enroll depends on your work status and whether you have other insurance

Most people become may be able to access for Medicare the month they turn 65. However, the month you should actually sign up is different from the month you become may be able to access — and missing the enrollment window can cost you in penalties for the rest of your life. If you are still working at 65 and have health insurance through your job, you may not need to enroll right away. If you are retired or your employer coverage is ending, you should enroll during your may be able to access month or within a specific window around it.

The rules are strict about timing. Medicare has an Initial Enrollment Period that runs for seven months: three months before the month you turn 65, the month you turn 65, and three months after. If you miss this window and do not have a valid reason, you will pay a permanent penalty on your Part B and Part D premiums for as long as you have Medicare.

Key Takeaways

Your Initial Enrollment Period is seven months long: three months before you turn 65, your birth month, and three months after — and missing it triggers permanent penalties.
If you are still working and covered by your employer's health plan, you may delay enrollment without penalty as long as you enroll within eight months of leaving that job or losing that coverage.
You must enroll in Part A (hospital insurance) and Part B (medical insurance) during your Initial Enrollment Period, even if you do not plan to use them right away.
Part D (prescription drug coverage) has its own enrollment important date; missing it costs you a penalty added to your premium every month you go without it.
You can enroll online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.

If you are still working at 65

If you are employed and your employer offers health insurance, you do not have to enroll in Medicare at 65. You can delay Part B enrollment without penalty as long as you are covered by your employer's plan and you are actively working. This is called creditable coverage, and it protects you from the late-enrollment penalty.

However, you should still enroll in Part A (hospital insurance) at 65 even if you delay Part B. Part A is usually free if you or your spouse paid Medicare taxes for at least 10 years, and there is no penalty for enrolling early. Enrolling in Part A also protects you if you have an accident or unexpected illness that requires hospitalization.

Once you leave your job or your employer coverage ends, you have eight months to enroll in Part B without penalty. If you wait longer than eight months, Medicare will charge you a permanent 10% increase on your Part B premium for each year you delayed. That penalty stays with you for life.

If you are retired or losing employer coverage

If you are not working or your employer coverage is ending, you should enroll in Medicare during your Initial Enrollment Period — ideally in the month you turn 65 or shortly before. Waiting until after your three-month window closes will trigger the late-enrollment penalty, even if you have other insurance like COBRA or a spouse's plan.

The only exception is if you have other creditable coverage — meaning health insurance that is at least as good as Medicare. This might be coverage through a spouse's employer, COBRA, or a retiree health plan from a former employer. If you have creditable coverage, you can delay Part B enrollment, but you must show proof when you do enroll. Without documentation, Medicare will assume you do not have creditable coverage and will assess the penalty.

Part D (prescription drug coverage) also has strict enrollment rules. If you go without Part D coverage and do not have creditable drug coverage, you will pay a penalty of about 1% of the national average Part D premium for each month you were uninsured. That penalty is added to your premium permanently.

How to enroll and what documents you will need

You can enroll in 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 enrollment is usually the fastest — you can complete it in about 10 minutes if you have your Social Security number and information about any current health coverage.

If you are still working and want to delay Part B, you will need to show proof of your employer coverage. Have your health insurance card or a letter from your employer's benefits department ready. If you are enrolling in Part D, you will need to know what prescription drugs you take so you can compare plans.

Social Security will send you a notice about Medicare may be able to access three months before you turn 65. This notice includes your Medicare number and information about enrollment. Keep this notice — you will need your Medicare number when you choose a Part D plan or a Medicare Advantage plan.

What happens if you miss your enrollment important date

If you miss your Initial Enrollment Period and do not have creditable coverage, you will owe a late-enrollment penalty. For Part B, this is 10% of the standard premium for each year you delayed, and it is added to your premium permanently. For Part D, the penalty is roughly 1% of the national average premium per month of delay, also permanent.

You can still enroll in Medicare after your Initial Enrollment Period ends, but only during the General Enrollment Period, which runs from January 1 to March 31 each year. Coverage would start July 1. If you have a may have access to life event — such as losing employer coverage, moving to a new state, or getting married — you may have a Special Enrollment Period that allows you to enroll outside the normal windows.

The penalty is calculated based on how long you went without coverage. If you delayed Part B for two years, you would pay a 20% increase on your premium for life. This is why it is important to enroll on time, even if you think you will not use Medicare right away.

Medicare Advantage and Medigap enrollment timing

If you are enrolling in Original Medicare (Part A and Part B), you can also choose a Medicare Advantage plan or a Medigap supplemental plan during your Initial Enrollment Period. Medicare Advantage plans have their own enrollment rules and important date that differ slightly from Original Medicare.

If you enroll in Original Medicare and later want to switch to a Medicare Advantage plan, you have until March 31 of the year after you turn 65 to make that switch. After that, you can only change plans during the Annual Enrollment Period (October 15 to December 7) or if you have a may have access to life event.

Medigap plans have different rules. If you enroll in Part B during your Initial Enrollment Period, you have a six-month window to buy a Medigap policy without the insurance company being able to deny you or charge you more based on your health. This window starts the month your Part B coverage begins. After six months, insurers can refuse to sell you a Medigap plan or charge you a higher premium.

Questions to ask your doctor or benefits counselor

Before you enroll, it helps to talk through your situation with someone who knows your health and finances. Here are the key questions to ask:

Should I enroll in Original Medicare or a Medicare Advantage plan?
Do I need a Medigap supplemental plan to cover costs that Original Medicare does not pay?
Which Part D plan covers the prescription drugs I take?
If I am still working, what counts as creditable coverage for my employer plan?
What is the important date for me to enroll without a penalty?

Your State Health Insurance information Program (SHIP) offers free counseling about Medicare enrollment. You can find your local SHIP by calling 1-877-839-2675 or visiting shiptalk.org. A counselor can walk you through your options and help you understand what the different plans will cost you.

Frequently Asked Questions

Can I enroll in Medicare before I turn 65?

Yes. Your Initial Enrollment Period starts three months before you turn 65. You can enroll online, by phone, or in person during this time. If you enroll before your birth month, your coverage will start the month you turn 65.

What if I am still working and do not want Medicare yet?

You can delay Part B if you have employer coverage and are actively working. You must enroll in Part A, but you have eight months after you leave your job to enroll in Part B without penalty. Document your employer coverage in case you need to prove it later.

Do I have to choose a Part D plan when I enroll in Medicare?

You do not have to choose a plan during your Initial Enrollment Period, but if you go without prescription drug coverage and do not have creditable drug coverage elsewhere, you will pay a permanent penalty. It is usually better to enroll in a plan even if you do not take many medications.

What happens if I enroll late but have a good reason?

Some situations allow you to enroll outside your Initial Enrollment Period without penalty. These include losing employer coverage, moving to a new state, getting married or divorced, or having a significant change in income. Contact Medicare at 1-800-MEDICARE to ask if your situation qualifies.

Can I change my mind after I enroll?

Yes, but only during specific windows. You can switch between Original Medicare and Medicare Advantage plans during the Annual Enrollment Period (October 15 to December 7) or if you have a may have access to life event. Medigap plans have different rules — you have the most flexibility if you enroll within six months of starting Part B.

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.