When to Sign Up for Medicare Part B — Your Enrollment Windows Explained

The Basic Rule: Sign Up During Your Initial Enrollment Period

You have a seven-month window to sign up for Medicare Part B without penalty, and it starts three months before the month you turn 65. If you turn 65 in June, your window opens in March and closes in September. You must act during this window — waiting costs you money in the form of a permanent penalty on your Part B premium.

The penalty is 10 percent of the standard Part B premium for each full year you delay after your Initial Enrollment Period ends. That penalty stays on your bill for as long as you have Medicare Part B. There is no way to remove it later, even if you eventually sign up.

Your Initial Enrollment Period is the only time you can sign up without proving you had other coverage. If you miss it and do not have a valid reason, you will pay the penalty and may have a gap in coverage.

Key Takeaways

Your Initial Enrollment Period is seven months long: three months before you turn 65, the month you turn 65, and three months after.
If you miss your Initial Enrollment Period and do not have employer coverage or another valid reason, you will pay a permanent 10 percent penalty on your Part B premium.
You can sign up through Social Security, Medicare.gov, or by calling 1-800-MEDICARE during your enrollment window.
If you are still working and covered by your employer's health plan, you may have a Special Enrollment Period that lets you delay Part B without penalty.
Once you turn 65, you must have Part B or pay the penalty — there is no option to go without coverage and avoid the fee.

Who Can Delay Part B Without Penalty

You can delay Part B past your Initial Enrollment Period without penalty if you have active employer coverage — meaning you or your spouse is still working and covered by a group health plan through that job. This includes coverage from a current employer, a spouse's current employer, or COBRA continuation coverage from a recent job.

If you have employer coverage, you have an eight-month Special Enrollment Period that starts when your employment or coverage ends, whichever comes first. During this window, you can sign up for Part B without penalty. You must sign up within this eight-month window or you will owe the penalty.

Retiree health plans from a former employer do not count as active employer coverage. Neither does coverage from a spouse's former employer. If you are retired and on a retiree plan, you must sign up for Part B during your Initial Enrollment Period or pay the penalty.

How to Sign Up During Your Enrollment Period

You have three main routes to sign up for Part B. The fastest is usually through Social Security, because they already have your information on file. Go to ssa.gov, sign into your My Social Security account, and look for the Medicare option. You can complete the process online in about 10 minutes.

You can also sign up through Medicare.gov. Create a Medicare.gov account, go to "Manage Your Health Care," and select the option to sign up for Part B. This route takes slightly longer because Medicare will ask you to verify your identity, but it works if you do not have a Social Security account set up yet.

The third route is to call 1-800-MEDICARE and speak to a representative. They can sign you up over the phone and answer questions about your specific situation. This is the best choice if you are unsure whether you may have access to for a Special Enrollment Period or if you need help understanding the penalty.

What Happens If You Miss Your Enrollment Period

If you do not sign up during your Initial Enrollment Period and you do not have a valid reason to delay, you will owe a permanent penalty. 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 delay for three years, you pay 30 percent extra on top of your regular premium for the rest of your life.

You can sign up during the General Enrollment Period, which runs January 1 through March 31 each year. Coverage starts July 1 of that year. However, you will still owe the penalty unless you have documentation of creditable coverage — meaning you had health insurance through another source during the time you were not on Part B.

The only way to avoid the penalty is to prove you had other coverage. This means a group health plan through an employer, COBRA, a spouse's plan, or certain other government programs. You will need to provide documentation to Medicare showing the dates you were covered. Without this proof, the penalty is permanent.

Special Situations That Change Your Timeline

If you are a federal employee, you may have different rules. Federal employees and retirees covered under the Federal Employees Health Benefits Program (FEHB) can delay Part B without penalty while covered by FEHB. You have an eight-month Special Enrollment Period after your FEHB coverage ends.

If you are on disability and under 65, you are automatically enrolled in Medicare Part A after 24 months of receiving disability benefits. You do not have to sign up. Part B is optional, but if you want it, you can sign up anytime without penalty as long as you are still receiving disability benefits.

If you are a veteran, VA coverage does not count as creditable coverage for the purpose of avoiding the Part B penalty. If you rely only on VA health care and do not sign up for Part B during your Initial Enrollment Period, you will owe the penalty. You can have both VA coverage and Medicare Part B at the same time.

Documents and Information You Will Need

To sign up for Part B, have your Social Security number, Medicare number (on your red, white, and blue Medicare card), and proof of citizenship or legal residency ready. If you are signing up online through Social Security or Medicare.gov, you will need to verify your identity, which usually means answering security questions based on your credit history.

If you are signing up by phone or in person, bring your Medicare card and a photo ID. If you are claiming a Special Enrollment Period because of employer coverage, have the name of your employer and the date your coverage ended. If you are claiming creditable coverage from another source, gather documentation showing the dates you were covered — this might be a letter from your former health plan, a pay stub showing coverage, or a benefits statement.

You do not need to bring anything if you are signing up through your Social Security account online. The system will pull your information automatically and confirm your enrollment status within a few days.

What Happens After You Sign Up

Once you sign up, Medicare will send you a confirmation letter within two weeks. Your Part B coverage starts on the first day of the month after you sign up, unless you sign up during the three months before you turn 65 — in that case, coverage starts the month you turn 65.

Your Part B premium will be deducted from your Social Security check each month, unless you ask to pay Medicare directly. The standard premium changes each year. In 2024, the standard Part B premium is $164.90 per month, but this amount varies by income and changes annually.

You will receive your Medicare card in the mail. Use it to show providers that you have coverage. Part B covers doctor visits, outpatient care, and certain medical equipment and supplies. It does not cover hospital stays (that is Part A) or prescription drugs (that is Part D).

Frequently Asked Questions

What if I turn 65 but am not ready to retire?

You still must sign up for Part B during your Initial Enrollment Period or pay the penalty — unless you have active employer coverage through your current job. If you are still working and covered by your employer's health plan, you can delay Part B without penalty. Once you leave that job or lose that coverage, you have eight months to sign up.

Can I sign up for Part B after I turn 65 if I missed my window?

Yes, but you will owe a permanent penalty unless you have proof of creditable coverage during the time you were not enrolled. You can sign up during the General Enrollment Period (January 1 through March 31), with coverage starting July 1. Bring documentation of any other health insurance you had during the gap.

Do I have to sign up for Part B if I have VA coverage?

No, Part B is optional if you have VA coverage. However, VA coverage does not count as creditable coverage, so if you skip Part B and later want to sign up, you will owe the penalty. Many veterans carry both VA coverage and Part B because they cover different services.

What if my employer says I do not need Medicare because I am still working?

Your employer is wrong. You must sign up for Part B during your Initial Enrollment Period or pay the penalty, even if you are working and have employer coverage. The only exception is if you have active group health plan coverage through your current job — in that case, you can delay without penalty, but you must sign up within eight months of leaving that job.

How much will Part B cost me?

The standard Part B premium varies by year and by income. Higher earners pay more through an Income-Related Monthly Adjustment Amount (IRMAA). The standard premium is deducted from your Social Security check each month. You can call 1-800-MEDICARE to find out what your specific premium will be based on your income.

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.