@nataliaqueensly It will be REQUIRED for SEPs, but you'd be doing yourself an extreme disservice by not switching things to state B now. Should it come to state C not taking your utility bill, or you don't cancel it in line with the date your lease/mortgage ends, it's going to come to the Government category.
Snowbirds basically can't shop on
healthcare.gov outside open enrollment in their residency state. Very few states offer nationwide coverage anymore, so they basically need to get a plan from that state and get all non-ER care there. Some plans allow out-of-state Minute Clinics, Urgent Cares, and Pharmacies, but not for repeat use.
Non-ACA/off-marketplace plans are a terrible idea because an increasing number of states either ban or heavily restrict them, even if bought from another state. E.g. MN only allows two separate 120-day plans within 18 months. If you go over that, by say buying a 1-year plan from Florida, the hospital/doctor must ignore it and bill you full price.
Snowbirds, by definition, pay for property in more than one state and switch between them seasonally. They never stay more than 3-4 months, so their DL and Plates are in the residency one. As mentioned earlier, this makes it IMPOSSIBLE for them to legitimately get any Special Enrollment Periods. Some try, but then the IRS realizes what's happening and orders the plan retroactively terminated or claws the subsidies back.
Snowbirds still need to tell the insurer the car is "garaged" elsewhere, but not many insurers play ball with that especially in states with stricter insurance laws.
E.g. people who go to FL to avoid MN taxes then get shellacked with FLs higher insurance prices which then gets worse when MNs higher limits are forced onto that same policy when the garage location changes.
They also have access to ZERO services in the other state, so they can be royally fucked by hospital bills, court judgements, employment/taxes, and the like because they have either two of something or only protection for the one (e.g. MN hospitals can't garnish a MN house or MN taxed income beyond a payment plan).