Eligibility/Medicare Part B

You are automatically eligible for Part B if you are eligible for premium-free Part A. You are also eligible for Part B if you are not eligible for premium-free Part A, but are age 65 or older AND a resident of the United States or a citizen or an alien lawfully admitted for permanent residence. In this case, you must have lived in the United States continuously during the 5 years immediately before the month during which you enroll in Part B.

Source: Medicare.gov