There is nothing nuanced about that. You look into 2 places and see read it for yourself. Stop spreading lies.
—-
https://app.leg.wa.gov/RCW/default.aspx?cite=1.90.100
RCWs > Title 1 > Chapter 1.90 > Section 1.90.100
RCW 1.90.100
Personal income tax prohibition.
Neither the state nor any county, city, or other local jurisdiction in the state of Washington may tax any individual person on any form of personal income. For the purposes of this chapter, "income" has the same meaning as "gross income" in 26 U.S.C. Sec. 61.
——
https://uscode.house.gov/view.xhtml?req=granuleid:USC-prelim...
Gross income defined
(a) General definition
Except as otherwise provided in this subtitle, gross income means all income from whatever source derived, including (but not limited to) the following items:
(1) Compensation for services, including fees, commissions, fringe benefits, and similar items;
(2) Gross income derived from business;
(3) Gains derived from dealings in property;
(4) Interest;
(5) Rents;
(6) Royalties;
(7) Dividends;
(8) Annuities;
(9) Income from life insurance and endowment contracts;
(10) Pensions;
(11) Income from discharge of indebtedness;
(12) Distributive share of partnership gross income;
(13) Income in respect of a decedent; and
(14) Income from an interest in an estate or trust.
