In-depth guides on tax residency, day counting, and compliance -- written for people whose tax bill or immigration status depends on getting the numbers right.
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.
Turn your location history into a verified day-by-day timeline. Run the real compliance math, set threshold alerts, and build an evidence trail that holds up to scrutiny.
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