An individual is eligible for premium-free (no cost) Medicare Part A (hospital insurance) if he or she is 65 or older and receiving, or eligible for, retirement benefits from Social Security or the Railroad Retirement Board, or is younger than 65 and has received Railroad Retirement disability benefits for the prescribed time and meets the Social Security Act disability requirements, or had Medicare-covered government employment, or is younger than 65 and has end-stage renal disease (ESRD). If an individual is not eligible for premium-free Medicare Part A, he or she can buy Part A by paying monthly premium if he or she is 65 or older and enrolled in Part B, a resident of the United States, and either a citizen or an alien lawfully admitted for permanent residence who has lived in the United States continuously during the 5 years before the month in which they apply.