The California Franchise Tax Board runs one of the most aggressive residency audit programs in the country. Surviving it requires documentation — precise, date-stamped, audit-ready documentation — not just an updated driver's license.

Most people who know about the Substantial Presence Test think they understand it. They've heard '183 days' and built their travel plans around that number. The IRS knows it too.

The 90/180 rule uses a rolling window, not a fixed calendar period. The 180-day window doesn't reset on a specific date. Most travelers get this wrong, and border officers know it.

If you're leaving California or New York for good, which state fights harder? Both have dedicated audit units and win large cases years later—but California is a domicile state while New York's statutory resident rules are a mechanical trap. Here's how the difference shapes what you document after you move.

I spent eight years at the IRS before I left to work from wherever I wanted. So I knew the rules cold. And I still watched person after person get blindsided by the same thing: they thought leaving the US was a decision they made. It isn't. It's a calculation.

The Canadian citizenship rule is not simply “live in Canada for three years.” Your five-year window moves, pre-PR time earns half-credit, and one missing trip can erase a thin margin over 1,095 days.

The FEIE physical presence test does not ask whether you spent 330 days outside the United States in a calendar year. It asks whether you spent 330 full days inside foreign countries during a qualifying 12-month period—and that distinction can decide the result.

Staying below 183 days does not automatically keep you non-UK resident. Your prior residence, workdays, family, accommodation, and even where you are at midnight can lower the line.