Medicare is a federal program, but the version of it you can actually buy is intensely local. Which Medicare Advantage plans and carriers are available comes down to your county. Whether you can buy or switch a Medigap supplement without a health review depends on your state's rules. Even the mix of Part D drug plans shifts from one state to the next. This is your starting point: pick your state below for a plain-English guide to the carriers, the Medigap rules, and how enrollment works where you live. Florida and California go deeper still, with regional breakdowns.
Original Medicare, Parts A and B, works identically in all 50 states. Almost everything else is local. Medicare Advantage plans are approved and priced county by county, so the plan that is a great deal one county over may not be sold where you live. Medigap is sold under federal plan letters, but each state sets the rules for how easily you can buy or switch one, and a handful of states are far more generous than the rest. And the private Part D drug plans available, along with which pharmacies are preferred, differ by region too. The guides below sort all of that out state by state.
Two states, Florida and California, have markets big and varied enough that we break them down by region, so you can see the local carriers and market character where you actually live.