How do I sign up for Medicare Part B if I already have Part A?

Most readers here have already been on Medicare Part B either recently or for several years. However, maybe you have a spouse/partner, or know someone else who has Medicare Part A (Hospital) but not Part B (Medical). Please pass this information on to those that are needing help to sign up for Medicare Part B. This is especially applicable during this COVID lockdown time when in-person visitation to your local Social Security Administration office has either been difficult or impossible.

The following paragraphs are from the FAQ section on the Social Security Administration’s website:

How do I sign up for Medicare Part B if I already have Part A?

If you are already enrolled in Medicare Part A and you would like to enroll in Part B, please complete form CMS-40B, Application for Enrollment in Medicare – Part B (Medical Insurance). If you are applying for Medicare Part B due to a loss of employment or group health coverage, you will also need to complete form CMS-L564 (Request for Employment Information).

You may complete the forms online by visiting the Apply for Medicare Part B Online During a Special Enrollment Period webpage; fax them to 1-833-914-2016; or return the forms by mail to your local Social Security office. If you have questions, please contact Social Security at 1-800-772-1213 (TTY 1-800-325-0778).

Note: When completing the forms CMS 40B and CMS L564:

  • State “I want Part B coverage to begin (MM/YY)” in the remarks section of the CMS 40B form or online application.
  • If your employer is unable to complete Section B, please complete that portion as best as you can on behalf of your employer without your employer’s signature.
  • Also submit one of the following forms of secondary evidence:
  • Income tax returns that show health insurance premiums paid.
  • W-2s reflecting pre-tax medical contributions.
  • Pay stubs that reflect health insurance premium deductions.
  • Health insurance cards with a policy effective date.
  • Explanations of benefits paid by the GHP or LGHP.
  • Statements or receipts that reflect payment of health insurance premiums.