Medicare is a federally funded program that provides health insurance to those age 65 and older as well as some other groups. It consists of several different parts, including Part B.

Medicare Part B is the medical insurance portion of Medicare. In 2017, over 30 million people were enrolled in Part B.

If you’re enrolled in Part B, you’ll pay a monthly premium as well as other costs like deductibles and coinsurance.

Continue reading as we take a deeper dive into Part B, its costs, and who can enroll.

Medicare Part B is medical insurance. Together with Medicare Part A (hospital insurance), it makes up what’s called original Medicare.

Part B covers medically necessary outpatient care. A service is considered medically necessary when it’s needed to diagnose or treat a specific condition or illness. Part B also covers some preventative care.

In some cases, you’ll be automatically enrolled in Medicare parts A and B when you turn 65 years old. However, some people will need to sign up through the Social Security Administration (SSA).

When you’re enrolled in PartB, you’ll receive your Medicare card through the mail. This card should say“MEDICAL” on it and also have an effective date listed.

Let’s break down the costsassociated with Part B in greater detail.

Monthly premium

If you have Part B, you’ll need to pay a monthly premium. The standard monthly premium for 2021 is $148.50.

However, the amount of this premium can increase based on your income. People with a higher income typically pay what’s known as an income-related monthly adjustment amount (IRMAA). For 2021, your income amount is calculated from your 2019 tax return.


A deductible is the amount that you have to pay out-of-pocket before Part B starts covering your outpatient services. For 2021, the Part B deductible is $203.


Coinsurance is the percentagethat you pay after you’ve met your deductible. For most services covered byPart B, you’ll pay 20 percentof the cost.


A copay is a set amount thatyou have to pay at the time you receive care. For Part B, you may have to pay acopay to a hospital if you use hospital outpatient services.

Out-of-pocket costs

Part B doesn’t cover some types of services like routine dental care or hearing aids. In these situations, you may have to pay for the entire cost of the outpatient services that you receive on your own.

You can use this tool that lets you search for any medical test or service to find out if it’s covered by Medicare.

The following individuals can enroll in original Medicare (parts A and B):

  • people age 65 and older
  • individuals with a disability who receive Social Security Disability Insurance
  • those who have end stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS)

Eligibility for Part B depends on whether or not you’re eligible for premium-free Part A. Most people get premium-free Part A because they’ve paid Medicare taxes while working.

People who can get premium-free Part A include:

  • those who are age 65 or older and eligible for, or currently receiving, Social Security or Railroad Retirement Board (RRB) benefits
  • people younger than age 65 who can collect Social Security or RRB disability benefits
  • individuals currently getting regular dialysis or who have received a kidney transplant and have applied for Medicare through the Social Security Administration.

People who can get premium-free Part A can also enroll in Part B when they’re first eligible for Medicare. If you’re not eligible for premium-free Part A, you have to meet the following guidelines to enroll in Part B:

  • be age 65 or older
  • live in the United States and be either a citizen or a permanent resident for at least 5 years

Enrollment in Medicare Part B

Some people areautomatically enrolled in Part A and Part B. These people include:

  • those who are going to turn 65 and are already receiving Social Security or RRB retirement benefits
  • people who have a disability and have been receiving disability benefits from Social Security or the RRB for 24 months
  • individuals with ALS who are receiving disability benefits

Some people will have to sign up with the SSA to enroll in parts A and B. These people include those not already collecting Social Security or RRB retirement benefits at age 65 or those with ESRD.

For people who are automatically enrolled, Part B coverage is voluntary. That means that you can choose not to have it.

Some people may wish todelay their enrollment in Part B because they already have health coverage.Whether or not you choose to delay enrolling in Part B can depend on thespecific health insurance plan that you have.

Deadlines for enrolling in Medicare Part B

Here are some important dates to keep in mind for enrolling in Part B:

  • Your 65th birthday: The initial enrollment period is a 7-month time span. It includes the month of your 65th birthday and the 3 months before and after. You can enroll in parts A and B at any point during this time.
  • January 1 through March 31: This is general enrollment. If you didn’t enroll in Part B during Initial Enrollment, you can do so at this time. You may need to pay a late enrollment penalty.
  • April 1 to June 30: If you chose to enroll in Part B during general enrollment, you may add a Part D (prescription drug coverage) plan during this period.
  • October 15 to December 7: This is the open enrollment period. If you want to switch from original Medicare (parts A and B) to a Part C (Advantage) plan, you can do so. You may also switch, add, or remove a Part D plan.
  • Special Enrollment: You may have employer-provided coverage in a group health plan. If so, you can sign up for parts A and B at any time during plan coverage or in the 8-month time period after leaving employment or the group health plan.

If you don’t sign up Part B when you’re first eligible, you may be required to pay a late enrollment penalty when you do choose to enroll. Additionally, you’ll need to wait until the General Enrollment period (January 1 through March 31 each year).

With the late enrollmentpenalty, your monthly premium may go up 10 percent of the standard premium for each 12-month period that you were eligible, butdidn’t enroll. You’ll continue to pay this penalty for as long as you’reenrolled in Part B.

For example, let’s say thatyou waited two years to enroll in Part B. In this case, you’d pay your monthlypremium plus 20 percent of the standard premium.

Part B covers a wide variety of medically-necessary outpatient services. Some examples include:

There are several thingsthat Part B doesn’t cover. These include:

Medicare Part B is the medical insurance part of original Medicare. It covers medically necessary outpatient services as well as some types of preventative care.

You’ll have to pay a monthlypremium for Part B. Other potential costs include deductibles, coinsurance, andcopays. You may also need to pay out-of-pocket for services that aren’t coveredunder Part B, like dental care and eye exams.

If you already collect Social Security benefits when you turn age 65, you’ll be enrolled in original Medicare automatically. Part B is voluntary. Some will need to sign up for original Medicare, so be sure to pay attention to important enrollment dates.

This article was updated on November 20, 2020, to reflect 2021 Medicare information.