Social Security Part B is health insurance for people 65 and older
Part B is the medical insurance portion of Medicare. It covers doctor visits, outpatient care, diagnostic tests, and certain preventive services. Unlike Part A, which is automatic when you turn 65, Part B requires you to sign up and pay a monthly premium — currently around $165 to $560 per month depending on your income, though this amount changes yearly.
Part B is separate from Part A (hospital insurance). You can have Part A without Part B, but most people who are may be able to access for Medicare end up enrolling in both because Part A alone leaves significant gaps in coverage.
If you delay signing up for Part B when you first become may be able to access, you may face a permanent penalty on your premium. The penalty is 10 percent for each 12-month period you could have had Part B but did not enroll, and it stays with you for life.
Key Takeaways
- Part B covers doctor office visits, lab work, imaging, and outpatient procedures — the things you do not stay overnight for.
- You pay a monthly premium for Part B, and you also pay a deductible and coinsurance when you use services.
- You must sign up for Part B during your initial enrollment window or face a permanent penalty on your premium.
- Part B does not cover dental, vision, hearing aids, or long-term care — you may need separate coverage or out-of-pocket payment for those.
What Part B actually covers
Part B pays for visits to doctors, specialists, and other medical professionals. This includes your primary care doctor, cardiologists, orthopedists, and mental health providers. It also covers lab work ordered by your doctor, X-rays, ultrasounds, CT scans, and other diagnostic imaging.
Outpatient procedures fall under Part B — things like cataract surgery done at an ambulatory surgery center, colonoscopies, and physical therapy. Part B also covers certain preventive services at no cost to you, including annual wellness visits, cancer screenings, and vaccinations like the flu shot and pneumonia vaccine.
Durable medical equipment such as wheelchairs, walkers, oxygen equipment, and diabetic supplies are covered under Part B. Home health services — nursing care and therapy provided at your home — are also covered if your doctor orders them and you meet specific conditions, like being homebound.
What Part B does not cover
Part B has clear limits. It does not cover dental work, routine eye exams, eyeglasses, or hearing aids. Cosmetic surgery is not covered. Long-term care in a nursing home or assisted living facility is not covered by any part of Medicare. Prescription drugs are covered under Part D, which is separate.
Part B also does not cover services deemed not medically necessary by Medicare, experimental treatments, or care received outside the United States (with rare exceptions). If you travel abroad, you will pay out of pocket for medical care unless you have a supplemental plan that covers international care.
How much you pay for Part B
Part B has three layers of cost: the monthly premium, an annual deductible, and coinsurance on each service. The monthly premium varies by income. If your income is below a certain threshold, you pay the standard premium. If your income is higher, you pay an income-related monthly adjustment amount (IRMAA) on top of the standard premium.
Once you meet your annual deductible — currently $240 but subject to change — Part B typically covers 80 percent of approved charges, and you pay 20 percent coinsurance. For some preventive services, you pay nothing once the deductible is met. For others, like office visits, you pay 20 percent coinsurance after the deductible.
If you have a Medigap (supplemental insurance) or Medicare Advantage plan, your out-of-pocket costs may be lower because those plans help cover the deductible and coinsurance that Part B does not pay.
When you must sign up for Part B
Your initial enrollment period is the seven-month window that includes the month you turn 65, the three months before, and the three months after. If you sign up during this window, your coverage starts the month you turn 65 (or the month after, depending on when in the month you sign up).
If you miss this window, you can sign up during the general enrollment period from January 1 to March 31 each year, but your coverage will not start until July 1 of that year. More importantly, you will owe a permanent penalty on your premium for each year you delayed.
There is one exception: if you are still working and covered by your employer's health plan, you may be able to delay Part B without penalty. You must sign up within eight months of losing that employer coverage to avoid the penalty.
Part B versus Part A: what is the difference
Part A covers inpatient hospital stays, skilled nursing facility care after a hospital stay, hospice care, and some home health services. Part B covers outpatient doctor visits, lab work, imaging, and preventive care. Together, they form the foundation of Medicare, though neither covers everything.
Part A is automatic — you do not have to sign up. Part B requires active enrollment. Part A is funded through payroll taxes you paid while working. Part B is funded by your monthly premium and general tax revenue. If you worked long enough to earn Social Security, you may have access to for Part A at 65. Part B has the same age requirement but no work history requirement.
How to enroll in Part B
You can sign up for Part B online through Medicare.gov, by phone at 1-800-MEDICARE, or in person at your local Social Security office. You will need your Social Security number and information about any current health coverage you have.
If you are already receiving Social Security benefits, you will be automatically enrolled in Part B at 65 unless you actively decline it. If you are not yet receiving Social Security, you must sign up for Part B yourself during your enrollment window.
Keep records of when you sign up. If you are later penalized for late enrollment, you can appeal if you can show you had good cause for the delay — for example, if you were working and covered by an employer plan, or if you received incorrect information from Social Security or Medicare.
Frequently Asked Questions
Do I have to take Part B if I am still working at 65?
Not if you have health coverage through your employer. You can delay Part B without penalty as long as you are covered by an employer plan and working. You must sign up within eight months of leaving that job or retiring to avoid a permanent premium penalty.
What happens if I miss my enrollment window?
You can sign up during the general enrollment period (January 1 to March 31), but your coverage will not start until July 1. You will also owe a 10 percent permanent penalty on your premium for each 12-month period you were may be able to access but did not enroll. This penalty stays with you for life.
Does Part B cover my medications?
No. Prescription drug coverage is Part D, which is separate. You must sign up for Part D during your enrollment window or when you first become may be able to access, or you may face a penalty. Part D is offered by private insurance companies approved by Medicare.
Can I use any doctor with Part B?
Most doctors accept Medicare Part B, but not all. Before scheduling an appointment, ask if the doctor accepts Medicare assignment. If they do, you pay your coinsurance and deductible. If they do not, you may pay more out of pocket.
What is the difference between Part B and a Medicare Advantage plan?
Part B is original Medicare — you see any doctor who accepts Medicare. A Medicare Advantage plan (Part C) is an alternative to original Medicare offered by private insurers. It usually has lower premiums and out-of-pocket costs but requires you to use doctors in the plan's network.