If at age 65 you meet eligibility requirements, Medicare will automatically enroll you in Part A. Medicare will send you an enrollment card and information two to three months before your 65th birthday.

If you aren't already receiving Social Security or other retirement-related benefits when you turn 65, you can enroll in Medicare Part A at any local Social Security office. If you delay enrolling after you turn 65, your coverage will be retroactive to six months before the month when you do enroll (though not earlier than your 65th birthday). If you're eligible to enroll because of disability rather than reaching age 65, your coverage is retroactive for a year from the date of enrollment.