In this installment of “A Pinch of SALT,” published by Tax Notes State, Partner Charlie Kearns examines Washington’s newly enacted “millionaire’s tax,” which takes effect in 2028 with returns due in 2029. The law imposes a 9.9% tax on Washington taxable income above $1 million, and introduces rules around residency, sourcing of income, and tax base calculations.
The article highlights key planning considerations, including the treatment of multistate income, limitations on the standard deduction, and potential traps for nonresidents working in Washington, underscoring the need for proactive planning as the regime takes effect.