Medicare Part B covers doctor visits, outpatient care, and medical equipment

Medicare Part B is the medical insurance portion of Medicare that pays for doctor office visits, lab tests, X-rays, ambulance services, durable medical equipment like wheelchairs and oxygen, and outpatient hospital procedures. It does not cover hospital stays — that is Part A. Part B requires a monthly premium, which is deducted from your Social Security check if you receive one, or billed separately if you do not.

Most people become may be able to access for Medicare at age 65, though some younger people with disabilities or end-stage renal disease can also receive it. You do not have to do anything if you are already receiving Social Security benefits — Medicare Part B is enrolled automatically three months before your 65th birthday. If you are not on Social Security, you must contact Social Security yourself to enroll.

The enrollment window matters. If you miss your initial enrollment period, you may pay a permanent penalty on your Part B premium for as long as you have Medicare. The penalty is 10 percent for each 12-month period you were may be able to access but did not enroll.

Key Takeaways

  • Part B covers doctor visits, lab work, outpatient procedures, and medical equipment, but not hospital stays.
  • You are automatically enrolled in Part B at age 65 if you receive Social Security; if not, you must contact Social Security to enroll yourself.
  • Your initial enrollment window is seven months long: three months before your 65th birthday, the month you turn 65, and three months after.
  • Missing your enrollment window triggers a permanent 10 percent premium penalty for each year you were may be able to access but did not sign up.
  • Part B premiums change yearly and are deducted from your Social Security payment or billed separately if you do not receive Social Security.

When your enrollment window opens and closes

Your Initial Enrollment Period is seven months long and centers on the month you turn 65. It runs from three months before your birthday through three months after. For example, if you turn 65 in June, your window opens in March and closes in September.

If you enroll during the three months before your 65th birthday, Part B coverage starts the month you turn 65. If you enroll in the month you turn 65, coverage starts the following month. If you enroll in the three months after your birthday, there is a one-month delay — so enrolling in August means coverage starts in October.

If you miss this seven-month window entirely, you enter the General Enrollment Period, which runs January 1 through March 31 each year. Coverage under General Enrollment does not start until July 1 of that year, and you will owe the permanent penalty on top of your regular premium.

How to enroll if you receive Social Security

If you already receive Social Security retirement, disability, or survivor benefits, you are enrolled in Part B automatically. You do not need to do anything. Medicare will send you a card in the mail about two weeks before your coverage starts.

You can decline Part B if you have other health coverage through an employer or union, but you must do this in writing. Contact Social Security and ask for Form CMS-L564 (Statement Regarding Your Medicare Part B Enrollment). You must return it before your coverage starts to avoid being enrolled and charged a premium you do not want.

If you decline Part B now but want it later, you can enroll during General Enrollment (January through March), though you will owe the permanent penalty unless you had creditable coverage — meaning health insurance as good as or better than Medicare Part B — for the entire time you were not enrolled.

How to enroll if you do not receive Social Security

If you are not receiving Social Security benefits, you must contact Social Security yourself to enroll in Medicare. Call Social Security at 1-800-772-1213 (TTY 1-800-325-0778) or visit your local Social Security office in person. You can also start the process online at ssa.gov, though you may need to finish by phone or in person.

Have your birth certificate, proof of citizenship or legal residency, and proof of income on hand when you call. Social Security will walk you through the enrollment process and confirm your coverage start date. They will also tell you what your Part B premium will be.

If you are still working and have health insurance through your employer, you may be able to delay Part B without penalty. This is called creditable coverage. You can enroll in Part B later without the permanent penalty, but you must enroll within eight months of losing your employer coverage or retiring, whichever comes first.

What documents and information you need

To enroll in Medicare Part B, have these items ready:

  • Your Social Security number
  • Your birth certificate or other proof of birth date
  • Proof of U.S. citizenship or legal residency (passport, naturalization papers, or green card)
  • Proof of income (recent tax return, W-2, or pay stub) if you are not yet receiving Social Security
  • Information about any current health coverage, including employer plans or TRICARE if you are military-connected

If you are explore by phone or mail, Social Security will tell you exactly which documents to send. If you explore in person at a Social Security office, bring originals or certified copies — photocopies are usually not accepted.

Part B premiums and what they cover

Part B premiums vary by income and change each year. In 2024, the standard premium is $164.90 per month for most people, but higher-income beneficiaries pay more through a system called Income-Related Monthly Adjustment Amount (IRMAA). Your premium is based on your income from two years prior, so 2024 premiums are based on your 2022 tax return.

Your Part B premium is deducted automatically from your Social Security check if you receive one. If you do not receive Social Security, Medicare sends you a bill each month. You can also set up automatic bank payments through Medicare.gov.

Part B covers 80 percent of approved charges for doctor visits, lab work, imaging, and outpatient procedures after you meet your annual deductible. You are responsible for the remaining 20 percent, which is why many people also purchase a Medigap or Medicare Advantage plan to cover these out-of-pocket costs.

What happens after you enroll

Once you enroll, Medicare will mail you a Medicare card showing your Part A and Part B coverage. This usually arrives within two weeks of your enrollment. Keep this card with you and show it to your doctor and any medical provider you visit.

Your coverage starts on the first day of the month you are may be able to access for, unless you enrolled after your initial window — in which case there may be a delay. Social Security will confirm your exact start date when you enroll.

After enrollment, you can change your coverage during the Annual Enrollment Period (October 15 through December 7 each year) if you want to add a Medigap plan, switch to Medicare Advantage, or make other changes. Outside this window, changes are limited to specific life events like moving, losing other coverage, or changes in income.

Frequently Asked Questions

What is the difference between Part A and Part B?

Part A covers hospital stays, skilled nursing facility care, hospice, and home health services. Part B covers doctor visits, lab tests, imaging, outpatient procedures, and medical equipment. Most people have both, though Part A is automatic at 65 and Part B requires active enrollment.

Can I delay Part B without a penalty?

Yes, if you have creditable coverage through an employer or union health plan. You can delay Part B and enroll later without penalty as long as you enroll within eight months of losing that coverage or retiring. You must tell Social Security you are delaying based on employer coverage when you first become may be able to access.

What if I miss my enrollment window?

You can still enroll during General Enrollment (January 1 through March 31), but coverage does not start until July 1 and you will owe a permanent 10 percent premium penalty for each year you were may be able to access but did not enroll. This penalty stays on your premium for life.

Do I have to enroll in Part B at 65?

No, but if you do not have other health coverage and you do not enroll, you will owe the permanent penalty when you do sign up later. The only exception is if you have creditable coverage through an employer or union plan.

How do I change my Part B coverage after I enroll?

You can make changes during the Annual Enrollment Period (October 15 through December 7). Outside this window, you can only change coverage if you have a may have access to life event, such as moving, losing other insurance, or a significant change in income. Contact Medicare at 1-800-MEDICARE to report a may have access to event.