How to Fill Out Medicare Forms CMS-L564 and CMS-40B

If you’re enrolling in Medicare Part B after having employer coverage, you’ll likely come across two important forms: CMS-L564 and CMS-40B. These forms play a key role in helping you avoid late enrollment penalties and ensuring your coverage starts when you need it.

For many people, this step can feel confusing—especially if you delayed Medicare while working. The good news is that once you understand what each form does and how they work together, the process becomes much more manageable.

This guide walks you through what each form is, when you need them, and exactly how to fill them out—step by step—so you can complete your Medicare Part B application with confidence.

 

What are Medicare Forms CMS-L564 and CMS-40B?

The CMS-L564 and CMS-40B are official Medicare Part B forms used when you’re enrolling outside of your Initial Enrollment Period—most often after leaving employer-sponsored health coverage.

• CMS-L564 is the Request for Employment Information
• CMS-40B is the Application for Enrollment in Medicare Part B

These forms are typically submitted together as part of your Medicare Part B application.

The purpose of these forms is simple:

• CMS-L564 proves you had qualifying employer coverage
• CMS-40B officially enrolls you in Medicare Part B

This combination allows you to enroll during a Special Enrollment Period (SEP) without facing late penalties.

If you want a broader look at how enrollment works, you can review the Medicare application process step-by-step. 

 

When Do You Need Forms CMS-L564 and CMS-40B?

You’ll need these Medicare Part B forms if you delayed enrolling in Part B because you had health insurance through an employer—either your own or your spouse’s.

Here are the most common situations:

• You continued working past age 65 and kept employer health insurance
• You’re retiring after age 65 and losing employer coverage
• You lost group health insurance due to job loss or company changes
• You’re transitioning from employer coverage to Medicare during a Special Enrollment Period

A Special Enrollment Period gives you a limited window—typically 8 months after employment or coverage ends—to enroll in Part B without penalties.

Timing matters here. Missing your SEP could mean waiting until the General Enrollment Period and potentially paying higher premiums for life. 

 

What Is Medicare Form CMS-L564?

The CMS-L564 form, also known as the Request for Employment Information, is used to confirm that you had employer-sponsored health coverage.

Purpose of CMS-L564

This form tells Medicare:

• You had active group health coverage
• The coverage was based on current employment
• You qualify for a Special Enrollment Period

This is important because Medicare needs proof that you didn’t delay Part B without a valid reason.

Who Fills Out the CMs-L564?

This form has two sections:

• Section A: Completed by you
• Section B: Completed by your employer (or former employer)

In most cases, you’ll send the form to your HR department to complete their portion.

Why It Matters

Submitting a correctly completed CMS-L564 helps you:

• Avoid late enrollment penalties
• Ensure your Medicare Part B application is approved without delays
• Keep your healthcare coverage continuous

Without this form—or without accurate information—you may be treated as if you delayed enrollment without qualifying coverage.

 

How to Fill Out Form CMS-L564 (Step-by-Step)

Filling out CMS-L564 is relatively simple, but attention to detail is important.

Section A – Completed by Applicant

In this section, you’ll provide basic information about your employment and coverage.

You’ll need to include:

• Employer name
• Employer address
• Your employment status (current or former employee)
• Information about your health coverage

Make sure the employer information matches what your HR department will provide in Section B.

Section B – Completed by Employer

Your employer (or HR representative) completes this section to verify your coverage.

They will include:

• Confirmation of group health plan coverage
• Coverage start date
• Coverage end date (if applicable)
• Employer signature and contact information

It’s a good idea to follow up with your employer to ensure this section is completed accurately and promptly.

 

What Is Medicare Form CMS-40B?

The CMS-40B form is the official Application for Enrollment in Medicare Part B.

This form is how you actually enroll in Part B coverage. While CMS-L564 confirms your eligibility, CMS-40B activates your benefits.

You should submit CMS-40B when:

• You’re ready to enroll in Part B
• You’re within your Special Enrollment Period
• You’re preparing to lose employer coverage

Submitting this form at the right time helps ensure there’s no gap in your healthcare coverage.

 

How to Fill Out Form CMS-40B

The CMS-40B form is short, but each section is important.

Personal Information

You’ll enter:

• Full legal name
• Social Security number
• Contact details

Make sure this matches your official records correctly. 

Medicare Number

If you’re already enrolled in Medicare Part A, include your Medicare number as it appears on your card.

Requested Coverage Start Date

You can choose when you want your Part B coverage to begin.

For example:

• The month after you retire
• The month your employer coverage ends

Choosing the right start date helps prevent coverage gaps.

Signature

Be sure to sign and date the form. Missing signatures are one of the most common reasons applications are delayed.

 

How to Submit Medicare Forms CMS-L564 and CMS-40B

Once both forms are complete, you can submit your Medicare Part B application in a few different ways. The options include:

• Online Through Social Security
• By mail
• In person

Each option is valid, and the best choice depends on what’s most convenient for you. Most applications are processed within a few weeks, but timing can vary depending on the accuracy of your forms, employer response time, and Social Security processing volume. 

Submitting complete and accurate Medicare Part B forms is the best way to avoid delays.

 

Common Mistakes When Submitting Medicare Forms

Many delays in Medicare enrollment come down to simple, avoidable mistakes.

Here are the most common ones:

• Incorrect coverage dates on CMS-L564
• Employer entering the wrong start or end date
• Missing signatures on one or both forms
• Submitting incomplete forms
• Waiting too long to request employer verification

How to Avoid Delays

To keep your application moving smoothly:

• Review both forms carefully before submitting
• Double-check all dates and personal information
• Follow up with your employer to complete Section B
• Submit your forms early within your Special Enrollment Period

Taking a few extra minutes to review your forms can save weeks of delays.

 

What Happens After You Submit Your Medicare Part B Application?

After submitting your forms, the process moves to review and approval.

In most cases, applications are processed within a few weeks. If anything is missing, Social Security may contact you.

Your Part B coverage will typically begin:

• The month after your application is processed, or
• On the start date you requested

Once approved, you’ll receive a notice confirming your enrollment, your coverage start date, and your monthly premium, and any adjustments.

 

FAQs About Medicare Forms CMS-L564 and CMS-40B

What is the CMS-L564 form used for?

The CMS-L564 form is used to verify that you had employer-sponsored health coverage based on active employment. This documentation allows you to qualify for a Special Enrollment Period and enroll in Medicare Part B without a late enrollment penalty. It also helps ensure your coverage starts at the correct time without delays.

What is the CMS-40B form?

The CMS-40B is the official Medicare Part B application used to enroll in medical insurance coverage. While the CMS-L564 confirms your eligibility, the CMS-40B is the form that actually initiates your enrollment and determines when your coverage will begin.

Who needs to complete CMS-L564?

Both you and your employer must complete the CMS-L564 form. You are responsible for filling out Section A with your employment details, while your employer or HR department completes Section B to verify your group health coverage. This step is required if you are enrolling in Part B after delaying coverage due to active employment.

Can I submit CMS-40B online?

Yes, in many cases through your Social Security account. This is often the fastest submission method. However, you can also submit your forms by mail or in person at a local Social Security office if you prefer.

What happens if my employer refuses to complete CMS-L564?

If your employer is unable or unwilling to complete the form, you can still move forward by providing alternative proof of coverage. This may include pay stubs showing health insurance deductions, official benefit summaries, or letters from your employer. In these situations, it’s a good idea to contact Social Security directly for guidance on acceptable documentation.

How long does Medicare take to process these forms?

Processing times can vary, but most Medicare Part B applications are completed within a few weeks. Delays are more likely if forms are incomplete, contain errors, or require additional verification. Submitting accurate and fully completed forms is the best way to ensure a smooth and timely approval.

Can I apply for Part B without these forms?

If you are enrolling during your Initial Enrollment Period, you typically do not need CMS-L564. However, if you are applying during a Special Enrollment Period after having employer coverage, both CMS-L564 and CMS-40B are generally required to avoid penalties and confirm eligibility.

 

Get Help with Your Medicare Part B Application

Filling out CMS-L564 and CMS-40B correctly is an important step in enrolling in Medicare Part B—especially if you’re transitioning from employer coverage.

While the forms themselves are straightforward, the timing and details matter. Submitting accurate information ensures you avoid penalties, prevent delays, and start coverage when you need it.

If you’re feeling unsure about any part of the process, you don’t have to navigate it alone. We are here to help you understand your options, avoid costly mistakes, and feel confident in your decisions. Whether you’re retiring, losing employer coverage, or planning ahead, expert guidance can make all the difference.