by Jerry Cornfield, Washington State Standard
April 8, 2026
Opponents of Washington’s new income tax law plan Thursday to formally launch their legal challenge to the constitutionality of the controversial statute.
Attorneys and plaintiffs have scheduled a 10 a.m. news conference to discuss details of the complaint and where the lawsuit will be filed. It will stream live on TVW.
Former state attorney general Rob McKenna, former state Supreme Court justice Phil Talmadge and Jackson Maynard, executive director of the Citizen Action Defense Fund, are expected to lead the litigation.
This will mark the start of a much-anticipated legal brawl on the law. Dubbed the “millionaires’ tax” by backers, it imposes a 9.9% tax on household wage earnings above $1 million.
Senate Majority Leader Jamie Pedersen, D-Seattle, a lead sponsor of the tax, said the lawsuit is “expected and welcomed.” He said one of the purposes of the bill was to get the legality of a progressive tax in front of the state’s high court for review.
“It’s great,” he said. “We will now have that robust argument.”
Gov. Bob Ferguson signed Senate Bill 6346 on March 30. It took effect immediately, ending Washington’s status as one of a handful of states that do not tax individual wage and salary income.
Collections will begin in 2029 and generate around $3 billion a year from an estimated 21,000 filers. That presumes it withstands this test in the courts and, presumably, on a future ballot.
Washington voters approved an income tax in 1932. But a year later, a divided state Supreme Court tossed it. Since then, voters have rejected variations of the idea multiple times, most recently in 2010 when the income threshold for individuals was $200,000.
The Citizen Action Defense Fund declared its intent to challenge the new law March 30 and said that McKenna, a 2012 Republican candidate for governor, would steer the legal team.
The complaint is expected to follow the framework of a February memo that McKenna prepared for the defense fund.
They contend the state Supreme Court has consistently held that income is property. Thus, any tax on income must be applied uniformly as the state constitution requires with property. That makes graduated income taxes unconstitutional, they will argue.
They’ll also argue today’s court is constrained by the 1933 legal precedent.
“Washington’s constitution is clear, and the courts have been equally clear for nearly a century — income is property, and progressive income taxes are unconstitutional under existing law,” McKenna said in March.
Backers of the tax are confident in the law’s legal sturdiness. They also think the passage of time and evolution of the court’s composition will result in a different outcome than 93 years ago.
Attorney General Nick Brown will wage the fight on behalf of the state.
“We will be defending the constitutionality of this law in court and expect to prevail,” Deputy Communications Director Mike Faulk wrote in an email Wednesday. “We’ll preserve our legal arguments for the anticipated filings.”
Pedersen, who is a lawyer, said not to be surprised when the superior court judge who gets the case rules the law is unconstitutional. Trial courts, he said, must follow Supreme Court precedents.
“Ultimately, this is a case that will be decided by the nine justices of the Supreme Court,” he said.
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