 Part B is an important part of original Medicare that is sponsored by the government. This video explains Part B, what it covers, when to enroll, and why to enroll. Medicare Part B is optional medical insurance purchased from the federal government. Part B plus Part A, hospital insurance, makes up original Medicare. And you must be enrolled in both if you want to join a Medicare health plan like those offered by Kaiser Permanente. Medicare Part B covers medical services such as doctor office visits, outpatient care, preventive services, lab and x-ray, durable medical equipment, ambulance and more. In most cases, your Medicare coverage may begin as early as the month you turn 65. You can sign up for Part B if you're at least 64 years and 9 months old, or have certain disabilities. Some people who are already receiving Social Security benefits may be automatically enrolled in Part B. You pay for Part B through a monthly premium. Part B premium amounts are set each year by Medicare and are based on your yearly income. You may sign up for Part B during your initial enrollment period. That's the three months before the month you turn 65, the month you turn 65, and the three months after. If you don't sign up during your initial enrollment period, you may have to pay a late enrollment penalty. This is why timing is so important. To enroll in Part B, call Social Security or visit their website at socialsecurity.gov. A few things to remember. Contact Social Security to learn more about Part B and to sign up. Your Part B premiums are paid to the federal government. You must sign up for Part B to enroll in a Medicare health plan. To learn more about Part B and enrolling in a Medicare health plan, go to the Kaiser Permanente Learning Center on this website.