Comment by yason

I hope you mind me not asking but while I know on some general level how things work in the US the details are infinitely interesting the deeper I think about this.

You're responsible for filing your own state taxes based on when/how/where you worked.

This seems like having so many knots left untied, considering how much importance one might expect to be placed for a fundamental question such as residency.

The obvious case is that it seems like people could just move into a state and never tell anyone and omit paying taxes. While there must be mechanisms to prevent or curb this, it still probably applies to a non-trivial minority of so-inclined people already? Not an option for people who want to settle, of course, but for certain people, living some months or years anonymously in a particular state might be a viable opportunity.

Do counties / cities / towns also lack similar logging of identity? How can they offer public services to people if they really don't know who the people are, and most importantly, if the people are residents or not? Does everyone just keep showing their utility bills? How do they deal with the various John Smiths moving from place to place -- inevitably to addresses where another John Smith was living before as there will be collisions without an unique identity? Or does the driving license become the de-facto proof of residence once people move it over, and the driving license has a unique number to differentiate between individuals regardless of name and address?

I mean, for the state government there's an inevitable and pragmatic need for uniquely identifying the people who live in the state and if there's no central registry then this need will be approxximated by various mechanisms so that the society can function at all.

Conversely, let's say the government does track down residents who nobody officially knows about. If the state government really doesn't know who lives in that state how could they impose liabilities such as taxes onto people whose identity and location and length of official residence they don't know? If I move in with my friend who lives in another state at which point can I still say "I'm just visiting, no taxes me for, thank you" and if the state were to disagree how would they go about establishing I was a resident after all? How would I prove I'm still actually a resident in the old state (if I were) vs how could they prove I'm no longer a resident in the old state (if I weren't)? What is the mechanism that prevents me from living in two states and claiming always in one that I'm resident in the other state?