Form CMS-40B: Request for Enrollment in Medicare Part B (Medical Insurance)
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JustFill is not affiliated with CMS (Centers for Medicare & Medicaid Services). This is an independent third-party tool to help you complete Form CMS-40B. Always download the current blank form from the official source and verify your completed copy before signing or submitting. Official Form CMS-40B from CMS (Centers for Medicare & Medicaid Services)
Form CMS-40B, Request for Enrollment in Medicare Part B (Medical Insurance) — titled Application for Enrollment on earlier editions and HCFA-40B under the agency's former name — is the CMS form for people who already have Medicare Part A and want to add Part B: during the Initial Enrollment Period, the General Enrollment Period (January 1 to March 31 each year) or a Special Enrollment Period after employer or union coverage ends. The current edition is CMS-40B (07/2025), a free fillable PDF from cms.gov. You fax or mail the signed form to your local Social Security office, with Form CMS-L564 completed by the employer when you claim a Special Enrollment Period; if you are ending an employer group plan, Social Security also accepts the application online. With JustFill you upload the blank CMS-40B PDF, the AI maps each field, you type or dictate your answers, and the first clean completed PDF download is included at no charge.
CMS-40B enrolls you in Medicare Part B when you already have Part A — most often because you delayed Part B while you or your spouse had group health coverage through current employment. The July 2025 edition is two pages plus an instruction page: Section 1 asks for your Medicare Number, name, mailing address, phone and email; Section 2 asks whether you had employer or union coverage since turning 65, the dates of that employment and coverage (which your employer confirms on Form CMS-L564, Request for Employment Information, returned with the application), whether anyone is requiring you to enroll, and which month you want coverage to start; Section 3 is your signature, with a witness only if you sign by mark. If you do not have Part A, the form tells you not to use it and to contact Social Security to apply for Medicare for the first time. JustFill lets you complete the CMS-40B online so your Medicare Number and dates are legible before you fax or mail it to your local Social Security office.
The official CMS-40B (07/2025) is a free three-page PDF from CMS at cms.gov/medicare/cms-forms/cms-forms/downloads/cms40b-e.pdf (instructions on page 1, the form on pages 2–3), listed on the CMS forms page as revision date 2025-07-01. It is already a fillable PDF, so there is nothing to buy or "unlock": fill it in Acrobat Reader, or open the same blank in JustFill to type or dictate every field in any browser — the first clean completed PDF download is included at no charge. Print it, sign by hand, and fax or mail it to your local Social Security office (ssa.gov/locator), with Form CMS-L564 if you are using a Special Enrollment Period.
Get the official Form CMS-40B PDF from CMS (Centers for Medicare & Medicaid Services)What each section of Form CMS-40B asks for. JustFill’s AI will detect these fields automatically when you upload the PDF — review the breakdown below so you know what to enter.
Your Medicare Number exactly as printed on your card, first, middle and last name with suffix, mailing address, phone number and email address. The form says all fields are required unless noted.
Whether you have (or had) coverage through an employer or union group health plan since turning 65, whether you were an international volunteer with non-profit health coverage, and — if either is Yes — the start and end dates (mm/yyyy, or "Not ended") of the employment, the volunteer work and the health coverage. Your employer completes Form CMS-L564 to confirm the same dates.
Item 4 asks whether an employer, insurer or other entity has asked or required you to enroll in Part B — if Yes, explain and attach proof. Then choose when coverage starts: if you enroll while still covered by the group plan or in the first full month after it ends, you may pick the first day of the month you enroll or the first day of any of the following three months.
Your signature and the date (mm/dd/yyyy). If you sign by mark (X), a witness who knows you must also print their name, sign and date.
A fictional retiree, Pat Example, has had Medicare Part A since turning 65 in 2021 but stayed on a spouse's employer plan. That plan ended in June 2026, so Pat is enrolling in Part B during the Special Enrollment Period.
1EG4-TE5-MK••
Masked on purpose. Copy the 11-character number exactly as printed on your red, white and blue Medicare card.
PAT EXAMPLE — 100 Sample Street, Austin, TX 78701
Use the name shown on your Medicare card; the address is where Social Security will write to you.
(555) 010-0199 — pat@example.com
The form marks all fields as required unless noted, and Social Security may call with questions.
Yes
Answering Yes triggers item 3 and is what makes this a Special Enrollment Period request.
No
Only for people who were covered while volunteering abroad for a non-profit.
Spouse worked for the employer 09/2001 – 06/2026; employer health coverage 09/2001 – 06/2026
Enter mm/yyyy. The employer confirms the same dates on form CMS-L564, which is returned with this application.
No
Tick Yes only if an employer or insurer is making you enroll, and attach the proof the form asks for.
The first day of the month you enroll
Because the enrollment falls within the first full month without the group plan, the form lets you pick this or the first day of any of the next three months.
PAT EXAMPLE — 09/02/2026
Sign by hand before faxing or mailing. A witness signs items 3–5 only if the applicant signs with a mark (X).
These values are made up. They are here to show what belongs on each line, not to be copied — every name, number, and address on your own Form CMS-40B has to be your own.
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CMS-L564: Request for Employment Information (Medicare)
Form SSA-44: Medicare Income-Related Monthly Adjustment Amount — Life-Changing Event
Form SS-5: Application for a Social Security Card
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Official source: Form CMS-40B on CMS (Centers for Medicare & Medicaid Services)’s website
Edition checked: CMS-40B (07/2025), "Request for Enrollment in Medicare Part B (Medical Insurance)", OMB No. 0938-1230, expires 07/31/2028; the CMS form page lists revision date 2025-07-01. Verified against the official source on .
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