It is an add-on to Original Medicare, Part A (hospital) and Part B (doctor). You may know it by another name, Medigap Plan or Med Supp. All three names: Medicare Supplement, Medigap, and Med Supp refer to the same program.
Why 3 names for the program?
The program “supplements” Original Medicare, or it fills “the gap” between Original Medicare and what you would otherwise pay for the services rendered. Medicare Supplement is the more formal name, again, the program “supplements” Parts A and B, which are referred to as Original Medicare.
Now that we know the names, what is it? Original Medicare pays about 80% of medical bills that are covered by Medicare. The Medicare Supplement pays, roughly, the remaining 20% of coverage.
You may have heard people refer to Plan C or Plan F. Those people were talking about Medicare Supplement Plans. There are approximately 11 lettered plans, not all Med Supp companies offer all the plans. The Federal Government requires that each lettered plan contains exactly the same coverage, no matter which company is selling it. Insurance companies may be selling the same plan for different prices.
All Medicare Supplement Plans have a premium, you will need to continue paying the premiums for Parts A & B also. Med Supps do not cover drugs so it is advisable that a Drug Plan is purchased in addition to a Med Supp.