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Fax Medicare Part B enrollment forms (CMS-40B, CMS-L564)

Fax your Medicare Part B application (CMS-40B, plus CMS-L564 if you're leaving an employer plan) to your local Social Security office. There is no national number: find your office's fax in the locator at ssa.gov/locator.

What you are sendingWhere the fax number is
Application for Enrollment in Medicare Part B (CMS-40B), with CMS-L564 or CMS-10797 if they apply to youYour local Social Security office's fax number. In the office locator, search your ZIP code, open Office information, and use the Fax number under Contact numbers. Open it on ssa.gov.

Checked against Sign up for Part B only, SSA.gov, Field Office Locator, SSA.gov on October 12, 2026.

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Send a fax to any US or Canadian number from your phone or computer. The steps on this page show how it will work.

  • No account or subscription
  • Pay only for pages that arrive
  • A delivery receipt for every fax

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Before you fax

  • If you're signing up because an employer group health plan is ending, you can apply online instead, any time of year during that Special Enrollment Period.
  • Leaving an employer plan: also send the Request for Employment Information (CMS-L564).
  • Special situations that qualify for their own enrollment period use form CMS-10797.
  • Outside these periods, Social Security asks you to call 1-800-772-1213 about the General Enrollment Period.
  • Coverage generally begins the first day of the month after you sign up.

How to send it without a fax machine

  1. Fill in and sign CMS-40B, and CMS-L564 or CMS-10797 if they apply to you.
  2. Find your local office's fax number in the Social Security office locator.
  3. Scan or photograph the forms, enter the office's fax number and add the pages.
  4. Send, and keep the delivery receipt as proof of the date you applied.

Questions

Is there one fax number for Medicare Part B forms?

No. Social Security asks you to fax or mail them to your local office; each office's fax number is in the office locator on SSA.gov.

Can I sign up for Part B online instead?

Yes, when you're ending an employer group health plan (a Special Enrollment Period). Otherwise call 1-800-772-1213.

When does Part B coverage start?

Social Security says coverage generally begins the first day of the month after you sign up.

Which forms do I need?

CMS-40B, the Part B application. Add CMS-L564, the Request for Employment Information, if you're applying because an employer plan is ending, or CMS-10797 if a special situation gives you its own enrollment period.

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