It was hell for me to prove my AZ residency, even back in the 70's. My parents moved there as soon as I graduated HS. They supported me, and I was clearly a dependent, but when i wanted to transfer to ASU in my senior year (I stayed in FL where I graduated HS), my dad had a screaming fight with the residency people. I told them I didn't have a DL (not possible in the Internet age), when I had a FL one, but even with their tax returns, it was a battle. The issue is that besides the revenue stream from out of state students, if they gave everyone residency who wanted to move to AZ for the weather, there would be way too many students! Just getting a DL, registering to vote, etc. is not really a statement of residency for a student. What people were told to do is come out, work for a year, so the intent of your move does not look like you are doing it to just get in state tuition. Since, back then, you could take 6 credits a semester with no out of state tuition (as well as summer school), people would move, work, take a couple of classes and then go to school once their residency status became clear.