How is my state tax residency decided in my first year, and can it differ from my federal status?

Yes, they're separate. Federal residency runs on the substantial presence and green-card tests, but each state sets its own rules, usually based on where you're domiciled and how many days you spend there, often a 183-day statutory-residency threshold. So you can be a federal nonresident but a state resident, or the reverse. States like Texas and Florida have no income tax, which simplifies things, while states like California and New York look closely at ties. Where you register your car, get your license, and keep your home all factor in. In a move-in year you may file a part-year state return. Check your state tax agency's residency rules, and consider wealthserene.com/assessments/tax-health.