Most people first become eligible for Medicare when they turn 65 and can enroll three months before their 65th birthday. Some people choose to delay Part B enrollment because they’re still working. However, if you delay Part B enrollment without having qualifying coverage, you could face late enrollment penalties. When to enroll in Part B is a personal choice, and the best decision depends on your situation.
If you are unsure where to start with enrolling in Medicare Part B, Chapter’s licensed Medicare Advisors can help you understand the best time and compare additional Medicare coverage options.
Read on to learn what goes into enrolling in Medicare Part B.
Key takeaways
People who receive Social Security or Railroad Retirement board benefits for at least four months before turning 65 are automatically enrolled in Medicare Part A and Part B.
Whether you should enroll in or delay Part B depends on whether you have qualifying health insurance coverage—and if that coverage costs you less than Medicare would.
Applying for Part B at the wrong time or missing a step can mean a late enrollment penalty or a gap in coverage.
Who needs to enroll in Medicare Part B?
If you begin receiving benefits from the Social Security Administration (SSA) or Railroad Retirement Board (RRB) at least four months before turning 65, you’ll be automatically enrolled in Part A and Part B. Everyone else who is eligible for Part B needs to sign up for it manually during the correct enrollment window.
What does Medicare Part B cover?
Medicare Part B offers medical insurance coverage. It’s built around outpatient and preventative care—the kind of care you get without being admitted to a hospital.
A few examples of what Part B covers include:
Outpatient care
Outpatient surgery
Preventative care
Ambulance services
Clinical research
Durable medical equipment (DME) like a wheelchair or a walker
There are several things that Part B doesn’t cover, including dental, vision, hearing, and prescription drug costs. There’s also no cap on out-of-pocket costs for either Part B or Part A. And if your provider doesn’t accept a Medicare-approved amount for services, you may also owe excess charges up to 15% over the approved amount.
Most people choose to enroll in additional Medicare plans to fill the gaps that Part B and Part A leave behind. A Medigap plan can be paired with Original Medicare and will reduce your out-of-pocket costs. Medicare Part D plans cover prescriptions and can also be paired with Original Medicare. Finally, Medicare Advantage can replace Original Medicare. Medicare Advantage covers the same things as Original Medicare. Most plans also cover prescriptions as well as dental, vision, and hearing care.
When should you enroll in Medicare Part B?
The Initial Enrollment Period for Original Medicare (Part A and Part B) lasts for seven months. For most, it begins three months before you turn 65. If you were born on the first day of the month, then your Initial Enrollment Period begins four months before you turn 65.
If you miss your Initial Enrollment Period and don’t qualify for a Special Enrollment Period, you must wait until the General Enrollment Period to enroll in Medicare. General Enrollment runs from January 1 to March 31 each year.
Because Medicare Part A is free for most people, it’s common to get it as soon as possible. On the flip side, most people pay the standard Part B premium, which is $202.90/month in 2026.
If you’re still working, you may want to delay Part B enrollment in favor of your employer-sponsored healthcare coverage. If your employer has 20 or more employees, then you’re eligible for the Part B Special Enrollment Period. This means you can delay enrollment without worrying about paying the Part B late enrollment penalty. If your employer has fewer than 20 employees, however, you should enroll in Medicare during your Initial Enrollment Period to avoid the penalty.
The following chart gives a good overview of Part B enrollment options if you work past 65, especially if you have other insurance coverage.
| Current health insurance | Part B enrollment options |
|---|---|
| Employer-sponsored coverage through you or your spouse’s job | If your employer has 20 or more employees, you can delay Part B enrollment without penalty. Once you stop working or lose your health insurance (whichever happens first), you have an 8-month Special Enrollment Period to enroll in Part B. |
| Retiree coverage | Ask your insurance provider if your coverage meets IRS guidelines for employer group health plan coverage. If it does, you may delay Part B enrollment. If it doesn’t you should enroll in Part B as soon as you’re eligible to avoid a late enrollment penalty. |
| COBRA coverage | COBRA doesn’t qualify you for delayed Part B enrollment. If you want to avoid the Part B penalty, you should enroll when you first become eligible. |
| No health insurance but still working | If you want to avoid the Part B penalty, you should enroll when you first become eligible. |
| Medicaid | Check whether your state enrolls you automatically. In most cases, your state will pay your Part B premiums while you have Medicaid. If your Part B premiums are covered and you need to sign up manually, it makes sense to do so. |
| Insurance from the Official Health Insurance Marketplace or other private insurance | If you want to avoid the Part B penalty, you should enroll when you first become eligible. |
| Insurance from the VA, CHAMPVA, or retiree TRICARE | If you want to avoid the Part B penalty, you should enroll when you first become eligible. |
| Active duty TRICARE | You can delay Part B enrollment without penalty. Once you either stop working or lose your health insurance (whichever happens first), you have an 8-month Special Enrollment Period to enroll in Part B. |
How do you enroll in Medicare Part B?
Social Security and Medicare enrollment work together because the Social Security Administration processes most applications for Medicare. The Railroad Retirement Board handles enrollment for its beneficiaries.
If you have a qualifying enrollment window, you can enroll in Medicare Part A and Part B with one application. If you sign up for Part A and choose to delay Part B enrollment, you can sign up for Part B during a Part B application.
Common ways to apply include:
Online: The fastest option for most people, through your “my Social Security” account.
By phone: Call Social Security at 800-772-1213, Monday through Friday, from 8 a.m. to 7 p.m., local time. TTY users can call 800-325-0778.
By mail, fax, or in person: Complete the paper enrollment form and send it via mail or fax, or drop it off at your local Social Security office.
Get help enrolling in Medicare Part B
Whether you need help figuring out when you should enroll in Part B or support during the application process, Chapter’s licensed, independent Medicare Advisors are here for you.
Chat with us today at 855-900-2427 or book an appointment at your convenience. We’re here to help!
Sources
Centers for Medicare & Medicaid Services. (n.d.). How do I sign up for Medicare? https://www.medicare.gov/basics/get-started-with-medicare/sign-up/how-do-i-sign-up-for-medicare
Centers for Medicare & Medicaid Services. (n.d.). Ready to sign up for Part A & Part B. https://www.medicare.gov/basics/get-started-with-medicare/sign-up/ready-to-sign-up-for-part-a-part-b
Centers for Medicare & Medicaid Services. (n.d.). What Part B covers. https://www.medicare.gov/providers-services/original-medicare/part-b
Centers for Medicare & Medicaid Services. (n.d.) When can I sign up for Medicare? https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-can-i-sign-up-for-medicare
Centers for Medicare & Medicaid Services. (n.d.) Working past 65. https://www.medicare.gov/basics/get-started-with-medicare/medicare-basics/working-past-65
Centers for Medicare & Medicaid Services. (n.d.). 5 things you need to know about signing up for Medicare. https://www.cms.gov/training-education/find-provider-type/employers-unions/top-five-medicare-enrollment
Social Security Administration. (2024, October 17). Sign up for Medicare Part B online, by fax, or by mail. SSA.gov. https://www.ssa.gov/blog/en/posts/2024-10-17.html
Social Security Administration. (n.d.). Sign up for Part B only. https://www.ssa.gov/medicare/sign-up/part-b-only
