How long before you're considered a resident of a state?

To domicile in Florida is easy to do. If you don't have a fixed sticks and bricks address, Florida has several Mail Forwarding services that you can legally set up domicile at and have your drivers license, car registration, and even get your voting privileges at. They don't have State income tax so you don't have to file state taxes for money earned in Florida, but as you learned you may have to pay state taxes for whatever other state you earned money in assuming that state has state taxes.