A Medicare supplemental plan is an insurance plan that is available to people who are on Medicare. Since Medicare does not cover all of the costs associated with health care, especially in your later years, a Medicare supplemental plan can be used in order to pay for these uncovered costs. The coverage of each of the plans, A through L, is laid down in law by the government, but the plans are purchased from private insurance companies.
Payments will not go to the US government or the Medicare program. They will go to a private insurance carrier. How exactly you make these payments will depend on your insurance carrier. Most major carriers will allow you to pay by sending in a check, setting up automatic withdrawals, or using a credit card. Some of them will allow you to pay online, while others will require payments to be made over the phone or in person. This will depend on the carrier
The premiums are set by the private insurance companies themselves. They will vary quite dramatically depending on which company you choose. When you decide on a carrier, it is important to understand how the pricing scheme works. If you sign up within the first six months of signing up for Medicare, you can not be subjected to medical screening, so your pricing can only be decided upon based on your age and location. Some will charge based on your age as you grow older, others on your age when you sign up, and still more based on your location. Those based on your age as you grow older are usually cheapest up front, but end up being a burden in the later years. If you sign up young, those based on your age when you sign up are usually best. If you are older, paying based on your location might be a better choice.