Check whether you are already enrolled automatically in Medicare Part B
If not enrolled, complete Form CMS-40B, Application for Enrollment in Medicare Part B
If you are enrolling after delaying Part B, also complete Form CMS-L564, Request for Employment Information
Submit the completed forms to your local Social Security office
Apply online through your Social Security account if eligible
Apply by phone by calling Social Security at 1-800-772-1213
Visit a local Social Security office in person
Provide any required proof of current or past employer coverage if requested
Wait for confirmation of your Part B enrollment and effective date