High-earners planning to leave Washington before ESSB 6346 kicks in routinely confuse residency with domicile. The distinction is centuries old, and after 2028 it will determine whether you pay a 9.9% state income tax.
Washington's 9.9% income tax takes effect January 1, 2028. This is your complete guide — from who owes it to how to plan for it — with links to 50+ detailed articles on every aspect of the new tax.
Part-year residents face a two-part calculation: all income during the resident period, Washington-source only during the nonresident period. Timing your move around income events can save six or seven figures.
Washington's income tax residency rules include a 30-day safe harbor — but it's more confusing than it sounds. Here's how the rule works, where the traps are, and what it means for tax planning.
