What Part B covers and when you need to sign up

Medicare Part B covers doctor visits, outpatient care, lab tests, and medical equipment — things Part A (hospital insurance) does not pay for. You pay a monthly premium for Part B, and it starts on the first day of the month after you sign up or become may be able to access.

Most people become may be able to access for Medicare at 65. If you are already getting Social Security or Railroad Retirement Board benefits, Medicare Part B is offered to you automatically. If you are not yet receiving those benefits, you need to sign up yourself during your may be able to access window.

The timing matters because signing up late can cost you more in premiums for the rest of your life. If you miss your initial enrollment window without a valid reason, you pay a permanent penalty on top of your regular Part B premium.

Key Takeaways

  • If you are already receiving Social Security at 65, Part B is offered automatically — you can accept it or decline it in writing.
  • If you are not yet on Social Security, you have a seven-month initial enrollment window: three months before the month you turn 65, the month you turn 65, and three months after.
  • You can sign up online at Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office.
  • Missing your enrollment window without a valid reason triggers a permanent 10 percent premium increase for each full year you delayed.
  • If you have employer coverage or other may have access to insurance, you may be able to delay Part B without penalty — but you must document this when you do sign up.

Signing up if you are already on Social Security

Social Security automatically sends you information about Medicare three months before you turn 65. The letter explains your options and tells you whether Part B enrollment is automatic or requires your action.

If Part B is automatic, you do nothing — it starts the month you turn 65. If you do not want Part B, you must decline it in writing. Send a signed letter to your local Social Security office or call 1-800-772-1213 to request a form. You have until the end of the month you turn 65 to decline.

If you decline and later change your mind, you can sign up during the General Enrollment Period (January 1 through March 31 each year), but you will pay the permanent late-enrollment penalty unless you have a valid reason for the delay.

Signing up if you are not yet on Social Security

Your initial enrollment window is seven months long: it begins three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, your window runs from March through September.

You can sign up during this window without penalty, even if you do not yet have Social Security benefits. You do not need to be receiving Social Security to enroll in Part B — you only need to be a U.S. citizen or permanent resident and at least 65 years old.

If you sign up during your initial window, Part B coverage begins on the first day of the month after you sign up, or on the first day of the month you turn 65 — whichever is later. For example, if you turn 65 on June 15 and sign up in April, coverage starts June 1. If you sign up in July, coverage starts August 1.

Three ways to sign up

Online at Medicare.gov: Go to Medicare.gov and select "Sign Up for Medicare" at the top of the page. You will need your Social Security number, date of birth, and citizenship information. You can complete the form in one sitting and receive confirmation right away. This is the fastest route if you have all your documents ready.

By phone: Call 1-800-MEDICARE (1-800-633-4227). Representatives are available Monday through Friday, 8 a.m. to 8 p.m. Eastern time, and Saturday 9 a.m. to 1 p.m. Eastern time. Have your Social Security number and date of birth ready. The call usually takes 10 to 15 minutes.

In person: Visit your local Social Security office. You can find the nearest office at ssa.gov/locator or call 1-800-772-1213. Bring your Social Security card, proof of citizenship (passport, birth certificate, or naturalization papers), and proof of residence (utility bill or lease). Walk-in appointments are available, but you can also schedule ahead to avoid waiting.

What happens after you sign up

After you sign up, Medicare mails you a Medicare card within two to three weeks. Your card shows your Medicare number and which parts of Medicare you have. Keep this card with you when you see doctors or go to the hospital.

Your Part B coverage begins on the date shown in your enrollment confirmation. You will receive a bill for your first month's premium, usually within a few weeks of enrollment. The standard Part B premium changes each year — Medicare announces the new amount in September for the following year.

You can pay your premium by mail, automatic bank withdrawal, or credit or debit card. If you sign up after your initial enrollment window, your coverage start date may be delayed, and you will owe the permanent late-enrollment penalty on top of your regular premium.

Avoiding the late-enrollment penalty

If you miss your initial enrollment window, you can still sign up during the General Enrollment Period (January 1 through March 31 each year). However, you will pay a 10 percent penalty on your Part B premium for each full year you delayed beyond your initial window. This penalty is permanent — it stays with you for life.

There are exceptions. If you had may have access to health insurance coverage (such as employer coverage or TRICARE) when you turned 65, you may be able to sign up later without penalty. You must show proof of that coverage when you enroll. Common may have access to coverage includes employer group health plans, COBRA, VA coverage, or Indian tribal health plans.

If you believe you have a valid reason for missing your window, bring documentation when you sign up. Examples include continuous employment with health insurance, military service, or living outside the United States. Social Security and Medicare staff can review your situation and may waive the penalty.

Part B costs and what to expect

Part B has two costs: a monthly premium and an annual deductible. The monthly premium is the same for most people, though higher earners pay more. The deductible is the amount you pay out of pocket before Part B starts covering your care.

After you meet your deductible, Part B typically covers 80 percent of approved services, and you pay 20 percent. Some services, like preventive care, are covered at 100 percent with no deductible. Your actual costs depend on which doctors you see and whether they accept Medicare.

You can reduce your out-of-pocket costs by enrolling in a Medigap policy (supplemental insurance) or a Medicare Advantage plan (Part C). These are separate from Part B and have their own enrollment windows and rules.

Frequently Asked Questions

Can I sign up for Part B after I turn 65?

Yes, but timing matters. If you sign up during your seven-month initial enrollment window (three months before through three months after you turn 65), there is no penalty. If you sign up later during the General Enrollment Period (January through March), you pay a permanent 10 percent premium increase for each year you delayed.

What if I have health insurance from my job?

You can delay Part B without penalty if your employer coverage is active. When you do sign up, bring proof of that coverage — your insurance card or a letter from your employer. This protects you from the late-enrollment penalty. You must sign up within eight months of losing that coverage to avoid penalties.

Do I have to sign up for Part B?

Part B is optional, but declining it has consequences. If you decline and later want to enroll, you can only sign up during the General Enrollment Period and will pay the permanent late-enrollment penalty unless you have a valid reason for the delay. Most people benefit from having Part B coverage.

What if I am still working at 65?

You can delay Part B if you have health insurance through your current job. Your employer must have at least 20 employees. When you leave that job or lose the coverage, you have eight months to sign up for Part B without penalty. Be sure to document your employer coverage when you enroll.

How long does it take to get my Medicare card?

Medicare mails your card within two to three weeks of enrollment. Your coverage begins on the date shown in your enrollment confirmation, even if your card has not arrived yet. You can use your confirmation letter at the doctor's office until your card arrives.