Washington state recently introduced an income tax.
"income tax just came into Washington's taxes" (said at 0:28:26)
In 2021, Washington state enacted a 7% tax on high-value long-term capital gains (exceeding $250,000). While capital gains are considered taxable income under federal tax law and in other states, Washington did not introduce a general personal income tax on wages, salaries, or ordinary income. Due to state constitutional restrictions, the measure was structured and legally upheld by the Washington Supreme Court as an excise tax on the sale or transfer of capital assets rather than an income tax.
- context: Trust Planning and the Washington State Capital Gains Tax (SSRN Electronic Journal 2021)
"On April 25, 2021, the Washington State Legislature enacted a new state capital gains tax. Before now, Washington state has been one of the few states that does not impose a tax on either income or capital gains. Because of limitations imposed by the Washington State Constitution, the legislature has been forced to characterize the tax as an excise tax, rather than treat it as an income tax as would the federal government and every other state." (abstract, passage verified)
openalexfull study (doi)