Medicare eligibility starts at age 65 for most people. However, some people may be eligible for Medicare earlier if they have a disability, End-Stage Renal Disease (permanent kidney failure requiring dialysis or a transplant), or ALS (also called Lou Gehrig’s disease) . If youre already receiving Social Security benefits, youll be automatically enrolled in Medicare Part A and Part B. If youre not receiving Social Security benefits, you can sign up for Medicare online, call Social Security, contact your local Social Security office, or call the Railroad Retirement Board if you or your spouse worked for a railroad. Its generally recommended to sign up for Medicare when youre first eligible to avoid a gap in coverage and/or late enrollment penalties.