Written by True Tamplin, BSc, CEPF®

Reviewed by Subject Matter Experts

Updated on February 04, 2024

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CMS-40B Form is utilized when you are already enrolled in Medicare Part A (Hospital Insurance), but not enrolled in Medicare Part B (Medical Insurance).

This form is utilized to switch your Medicare coverage to the benefit of becoming enrolled in both Part A and Part B.

Who Should Fill Out the Form CMS-40B?

Since Form CMS 40B is used to enroll in Medicare Part B Insurance, people who are eligible for it include:

  • People who are turning 65-years old
  • People who are under 65 years old, when they work for at least 10 years in a Medicare-covered job, have the end-stage renal disease (ESRD) or amyotrophic lateral sclerosis (ALS).

Have a question about CMS-40B? Click here.

Where Do I Find Form CMS-40B?

You can apply online or you can mail your completed CMS 40B, Application for Enrollment in Medicare - Part B (Medical Insurance) to your local Social Security office.

You can also fax your enrollment forms and evidence of employment and health coverage to your local Social Security office. Form CMS 40B can be downloaded from this website:

Requirements to be Submitted Together With Form CMS-40B

In order to complete the application using CMS 40B Form, you will have to submit the following forms:

Form CMS 15

This is a form for asking for a Medicare Advantage plan outside of the open enrollment period.

Form CMS L564

This is a request for Employment Information and required proof of employment, Group Health Plan (GHP), or Large Group Health Plan (LGHP) coverage

When to File For Form CMS-40B?

You can file Form CMS-40B as soon as you turn 65 years old, or no later than three months before your Medicare Part B coverage is due to expire.

You may also want to request Form CMS-40B if your Form CMS-20B expires, or is due to expire.

Form CMS-20B allows you to enroll in Medicare Part B Insurance before Form CMS-40B can be filed.

How Long Does It Take to Process Form CMS-40B?

CMS-40B Form submission typically takes about 4 to 6 weeks of processing.

What Are Some of the Benefits to Filing Form CMS-40b Form?

People who file Form CMS-40B will have their Part B coverage begin on the first day of the month they enroll.

Form CMS-40B also gives people the option to choose a private or preferred provider plan, or a Medicare Advantage plan instead of traditional Medicare coverage.

Form CMS-40B also allows people to enroll in Part D, the prescription drug benefit program.

The Bottom Line

Form CMS-40B allows people to enroll in Medicare Part B coverage when they turn 65 years old, or if they have worked for at least 10 years before the age of 65 and have been diagnosed with a terminal illness.

It also allows people to switch from traditional Medicare coverage to a private plan. Form CMS-40B is usually processed around 4 to 6 weeks.

By making Form CMS-40B your priority for your enrollment, you will ensure that you will be covered until your Medicare part A and B coverage ends.


About the Author

True Tamplin, BSc, CEPF®

True Tamplin is a published author, public speaker, CEO of UpDigital, and founder of Finance Strategists.

True is a Certified Educator in Personal Finance (CEPF®), author of The Handy Financial Ratios Guide, a member of the Society for Advancing Business Editing and Writing, contributes to his financial education site, Finance Strategists, and has spoken to various financial communities such as the CFA Institute, as well as university students like his Alma mater, Biola University, where he received a bachelor of science in business and data analytics.

To learn more about True, visit his personal website or view his author profiles on Amazon, Nasdaq and Forbes.

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