If you have Medicare Part A (Hospital Insurance) and you’re eligible to enroll in Medicare Part B (Medical Insurance) through a Special Enrollment Period (SEP), you have options for how to apply. You can complete the Part B SEP online or you can mail your completed CMS 40B, Application for Enrollment in Medicare - Part B (Medical Insurance) and CMS L564 - Request for Employment Information to your local Social Security office. You’ll also need to send any required proof of employment, Group Health Plan (GHP), or Large Group Health Plan (LGHP) coverage. You can also fax your enrollment forms and evidence of employment and health coverage to your local Social Security office. You can find your local Social Security office by clicking “SSA Office Locator” under the “Related Links” section below. Your employer doesn’t need to sign Section B of the CMS L564 form. State “I want Part B coverage to begin (MM/YY)” in the remarks section of the CMS 40B form or the online application. Visit faq.ssa.gov or call Social Security toll-free at 1-800-772-1213 (TTY 1-800-325-0778) for more information. NOTE: If you don’t already have Part A you can apply online at SSA.gov/benefits/medicare.