🏥 How to Fax Medicare Part B Forms CMS-40B and CMS-L564
Fax CMS-40B and CMS-L564 to your local Social Security office, because there is no national Social Security fax number for these forms. Both forms say to mail or fax them to your local office, and the SSA Office Locator at SSA.gov/locator shows each office's fax number. You can also sign up for Part B only online. A cover page plus your forms usually costs $2.99 for up to 3 pages and $0.99 for each extra page.
📋 In This Guide
Where the Forms Go
CMS-40B is the form you fill out to enroll in Medicare Part B, and CMS-L564 is the form that shows your group health plan coverage based on current employment. The current CMS-40B (07/2025) says to mail or fax your completed, signed form to your local Social Security office. The current CMS-L564 (revised 03/2025) says to mail or fax it together with your CMS-40B to your local Social Security office. Neither form prints a fax number.
The Social Security Part B page says to find your Social Security office and fax or mail the completed form. Social Security's forms page also lets you send forms to your local office by fax, by mail, or through the office's drop box, or upload them online.
The rule: there is no national fax number for CMS-40B or CMS-L564. Fax them only to your own local Social Security office, at the fax number the SSA Office Locator shows for that office.
Finding Your Office's Fax Number
Go to SSA.gov/locator and enter your ZIP code. The office page shows its contact numbers, including a fax number. If you are not sure which office serves you, or the locator shows no fax, call Social Security at 1-800-772-1213 (TTY 1-800-325-0778), Monday to Friday, 8 a.m. to 7 p.m. Do not use a fax number found on a forum or on another person's letter, because each office has its own.
You May Not Need to Fax at All
Social Security lets you sign up for Part B only online at ssa.gov/medicare/sign-up, if you already have a Medicare number and a valid email address. Its Part B page also says you can apply online when you are ending an employer group health plan. If the online route works for you, it is a good choice, and fax remains a simple option when you have paper forms signed and ready.
Who Fills Out Each Form
You, the person enrolling, fill out and sign CMS-40B. If you sign with a mark, a witness must sign too. CMS-L564 has two parts: you fill out Section A, and your employer fills out Section B to confirm your group health plan coverage based on current employment. If you or your spouse had coverage through a job, ask that employer's HR or benefits office to complete Section B, then send both forms together.
OverseasFax is not HIPAA compliant and does not sign a business associate agreement (BAA), which matters to doctors' offices and clinics. You may fax your own Medicare forms. For HR paperwork, see how to fax a COBRA election form, which often comes up at the same time.
Entering the Office's Fax Number
Select United States and type all 10 digits of the office's fax number, starting with the area code. Do not type the leading 1, because +1 is added for you, and the box removes a 1 if you type one. The pay button turns on only when all 10 digits are in. A number shown as (732) XXX-XXXX is entered as 732XXXXXXX. More help is in how to fax a US number online and how to fax from a Windows PC.
What to Put on the Cover Page and Each Page
On the cover page, write the office name, "Medicare Part B enrollment: CMS-40B and CMS-L564 attached", your full name, your Medicare number, your phone number, and the total page count. Put your name and Medicare number at the top of every page and number the pages, such as "Page 3 of 5". Send CMS-40B first, then CMS-L564, then any proof of job-based coverage Social Security asked you for.
The 8-Month Deadline
If you delayed Part B because you or your spouse were working and had job-based coverage, you have a Special Enrollment Period. It lasts up to 8 months after you or your spouse stop working, or after the job-based coverage ends, whichever happens first. Social Security says that if your employer group coverage since age 65 ended within the last 8 months, you can enroll without a penalty. Send your forms well before the 8 months end, and keep your confirmation email.
Cost, Your Record and a Failed Fax
If your cover page, CMS-40B and CMS-L564 come to 5 pages, the fax costs $2.99 + 2 x $0.99 = $4.97. With a page of coverage proof, 6 pages is $5.96. You see the total before you pay.
There is no account, nothing is printed on your document, and delivery usually takes a few minutes. The confirmation email shows the destination number, the page count and the time in US Eastern Time, which is your record of exactly when it was sent. If the fax cannot be delivered, the full amount goes back to your card automatically. If the office needs to fax you a page, our sister service GetAFax.com gives you a private US fax number for 24 hours for $5, for up to 30 pages, with faxes sent to your email as a PDF. For other Social Security paperwork, see how to fax Social Security, and for all US guides, see the US fax guide.
Why send it here
One price for the whole fax, shown before you pay, and nothing added at checkout.
Nothing is printed on your document. It arrives exactly as you uploaded it.
If it cannot be delivered, the money goes back to your card without you asking.
It works from anywhere in the US, in any browser, with no account.
Frequently Asked Questions
How much does it cost to fax CMS-40B and CMS-L564 to Social Security?
Is there a free way to send my Medicare Part B forms?
What is the Social Security fax number for Medicare Part B forms?
Can I fax CMS-40B to Social Security?
Do I fax CMS-L564 separately or with my CMS-40B?
My job coverage ends next month, can I fax my Part B forms to my local SSA office now?
Who fills out CMS-L564, me or my employer?
Can I sign up for Medicare Part B online instead of faxing CMS-40B?
How do I find my local Social Security office fax number for CMS-40B?
How do I type my Social Security office fax number?
Can Social Security fax me back about my Part B enrollment?
How do I keep a record that I faxed my Part B forms before the 8-month deadline?
My CMS-40B fax failed, will I be charged?
Is it safe to fax my Medicare number to a Social Security office?
Is OverseasFax HIPAA compliant for Medicare forms?
How long do I have to sign up for Part B after my employer coverage ends?
Does my CMS-40B need a witness?
What is the Social Security phone number for help with CMS-L564?
What should the cover page say when I fax CMS-40B and CMS-L564?
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