When you retire or lose benefit eligibility (you are already Medicare eligible) - Special Enrollment Period:
Contact Employee Benefits and request the SSA Request for Employment Information form (this form allows you to enroll and exempts you from the penalty for not enrolling when first eligible).
You will need an SSA Employment Verification form for you and/or your spouse if Medicare eligible
Request a “Letter of Entitlement” notice from the Social Security Office, this will be used to verify your enrollment in Medicare Part A & B to allow you to enroll in a Medicare Supplemental/Advantage plan.