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Adding Medicare Part B if You Already Have Part A

Adding Medicare Part B if You Already Have Part A

Medicare Part A and Part B make up Original Medicare. Part A covers hospital services, while Part B covers doctor visits and outpatient care. Most people sign up for both when they first become eligible, typically at age 65. However, it is possible to get Part A only and then add Part B later on.

If you already have Medicare Part A and want to also get Part B coverage, here is what you need to know.

Overview of Medicare Parts A and B

Medicare Part A, also known as hospital insurance, helps pay for inpatient hospital stays, skilled nursing facility care, hospice, and some home health services. Most Americans get premium-free Part A at age 65 because they or their spouse paid Medicare payroll taxes while working.

Medicare Part B is medical insurance that covers doctor services, preventive care, durable medical equipment, lab tests, x-rays, and more. Basically Part B covers medically necessary care provided in outpatient settings. You have to pay a monthly premium for Part B based on your income.

Most people enroll in both Part A and Part B during their initial enrollment period when they first become eligible for Medicare at age 65. However, it’s possible to get only Part A at first and add Part B later. Here’s how that works.

Why Only Enroll in Part A at First?

There are a few scenarios where Americans turning 65 may opt to only enroll in Medicare Part A to start with:

  • You want to keep contributing to an HSA – To make HSA contributions, you cannot have Medicare. Getting only Part A allows you to keep contributing to an HSA since you don’t have Part B.
  • You have coverage through work – Some people choose to keep employer health coverage and delay Part B. Part A may provide some secondary hospital benefits.
  • You missed Part B enrollment – If you missed signing up for Part B when first eligible, it can only be added later during the general enrollment period each year.
  • Financial reasons – Since Part B has a premium, some may try to delay enrollment due to cost concerns.

Unless you have creditable drug coverage elsewhere, you should enroll in a Medicare Part D prescription plan during your initial enrollment period, even if declining Part B.

Special Enrollment Period for Part B

The initial enrollment period (IEP) for Medicare spans 7 months around your 65th birthday. If you did not sign up for Part B during this time frame, you can enroll between January 1 – March 31 each year which is known as the general enrollment period.

Coverage will start July 1 if you apply during the general enrollment period. However, you may incur a 10% penalty for late Part B enrollment for every 12 months you delayed signing up.

An exception is if you have group health insurance through an employer. In that case, you can enroll in Part B penalty-free any time the employment coverage ends. This is called a Special Enrollment Period (SEP).

Some other examples where you may qualify for a Part B SEP include:

  • Moving back to the U.S. after living abroad
  • Losing Medicaid coverage
  • Leaving a Medicare Advantage Plan
  • Getting married or divorced
  • Retiring after 65 while covered under an employer plan

If you think a special circumstance makes you eligible to enroll in Part B, contact Medicare to request a Special Enrollment Period. This allows adding Part B outside of general open enrollment.

How to Apply for Part B

If you meet one of the enrollment periods outlined above, applying for Medicare Part B is easy. You can sign up online, over the phone, or by visiting your local Social Security office.


  • Visit to create a account.
  • Click “Apply for Part B” and follow the instructions to submit your application.

By Phone:

  • Call Social Security at 1-800-772-1213 to speak with a representative.
  • Let them know you want to enroll in Medicare Part B.
  • Be ready to provide personal information like your Social Security number.


  • Locate your closest Social Security field office via the SSA website.
  • Bring the completed Medicare Part B application form.
  • A representative will help process your enrollment application.

No matter which method you use, make sure to have your Medicare number from your Part A coverage card ready when applying for Part B. If approved, you’ll receive a new Medicare card in the mail that includes both Part A and Part B coverage.

When Coverage Begins

If you enroll in Medicare Part B during your initial enrollment period around age 65 or a special enrollment period later on, coverage will start the month after you apply.

For example, if you apply for Part B in May, your benefits would begin June 1st as long as you’re eligible. The start date may be slightly different if also enrolling in a Medicare Advantage Plan.

If adding Part B during the general enrollment period from January 1 to March 31 each year, coverage doesn’t begin until July 1. Remember this can result in a late enrollment penalty applied to your monthly Part B premium.

Cost of Medicare Part B

In 2023, the standard monthly premium for Medicare Part B is $164.90. However, if you are subject to a late enrollment penalty for not signing up when first eligible, you’ll pay more each month.

The late enrollment penalty is 10% of the standard premium for every 12-month period that you delayed enrollment. For example, if you wait 3 years to get Part B, your monthly premium would be 30% higher.

Some people with higher incomes also pay more for Medicare Part B each month based on IRS tax return thresholds. This is known as IRMAA (income-related monthly adjustment amount).

If you have Part A, make sure to add Part B as well during your initial enrollment period or special enrollment window to avoid lifetime late enrollment penalties. Having both Parts A and B will give you the full scope of Medicare coverage.

Coordinating with Other Insurance

Once you add Medicare Part B, you need to inform any other insurance providers that you now have Medicare coverage. This includes:

  • Employer or union group health plans
  • COBRA coverage
  • Retiree insurance
  • Medicaid
  • VA benefits
  • Individual health insurance

In many cases, Medicare becomes the primary payer and your other insurance becomes secondary. Failing to report your Medicare coverage can risk claim denials and coordination of benefit issues.

If you have Medicare and an employer plan, the employer coverage may ask you to re-enroll to change to supplemental or secondary payer status. Work with your benefits administrator to handle this properly.

Enrolling in Medicare Part D

Finally, understand that Medicare Part A and Part B do not cover prescription medications. You must enroll in a private Medicare Part D Plan for drug coverage. This can be done as a stand-alone plan or included with a Medicare Advantage Plan.

Make sure to compare Part D Plans and join one that covers your medications for the lowest cost. If you don’t sign up when first eligible, you may incur a lifetime penalty if you delay Part D enrollment.

Overall, it’s easy to add Medicare Part B later on if you only have Part A coverage initially. Just make sure to enroll during an approved enrollment period to avoid penalties. Then coordinate your benefits and add Part D prescription coverage. Having all parts of Medicare will give you comprehensive coverage.

We’re Here to Help

You do not have to spend hours reading articles on the internet to get answers to your Medicare questions. Give the licensed insurance agents at Senior Health Advocates a Call at (386) 222-3030. You will get the answers you seek in a matter of minutes, with no pressure and no sales pitch. We are truly here to help.


How can I add Medicare Part B if I already have Part A?

 To add Medicare Part B if you already have Part A, you will need to sign up for Part B.

How do I sign up for Medicare Part B?

 To sign up for Medicare Part B, you can apply online or complete the CMS-40B enrollment form.

I want to sign up for Part B, but I am already 65. Is there a penalty?

A: If you are already 65 and want to sign up for Part B, you may have to pay a penalty. The penalty is added to your monthly Part B premium.

How do I know if I am eligible to sign up for Medicare Part B?

 If you already have Part A, you are eligible to sign up for Medicare Part B.

Can I sign up for Part B if I am still covered under a group health plan?

 Yes, you can sign up for Part B if you are still covered under a group health plan. However, you will need to contact your employer or union to find out how your current coverage works with Medicare.

What forms and evidence do I need to send when signing up for Part B?

 When signing up for Part B, you will need to complete Section B of the enrollment form and provide any necessary forms and evidence of employment or group health plan coverage.

Do I need to pay a premium for Medicare Part B?

 Yes, you will need to pay a premium for Medicare Part B. The amount of the premium may vary depending on your income.

 When can I sign up for Medicare Part B?

 The initial enrollment period for Medicare Part B runs from January 1 to March 31. However, you can sign up for Part B anytime as long as you are eligible.

How can I sign up for Medicare Part B if I qualify for a special enrollment period?

 If you qualify for a special enrollment period, you can sign up for Medicare Part B by completing the application for enrollment and providing the necessary forms and evidence.

Is there any cost-saving program available for Medicare Part B?

Yes, there are cost-saving programs available for Medicare Part B. These programs can help reduce the cost of premiums and other out-of-pocket expenses for eligible individuals.


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