Medicare supplement policy versus Medicare Advantage. Medicare part A which is your hospitalization. Medicare Part B is outpatient, so your doctor visit, blood work, CAT scan, x-rays anything outpatient. Your premium for the part B is $134 in 2017, sometimes those numbers are different based on what your taxable income is for the previous year.
Your part A and part B of Medicare it's kind of like a piece of Swiss cheese, you have a lot of coverage, but there still a lot of holes and gaps in that coverage. Medicare pays 80% and you pay 20%, so if you're going to go with Medicare part A and Part B through the federal government you will need a supplement to cover those gaps in your coverage.
Image taken from Centers for Medicare and Medicaid Services handbook for “Choosing a Medigap Policy: A Guide to Health Insurance for People with Medicare” Section 1: Medicare Basics Page 7
