Washington's new "millionaires tax" is not even close to kicking in, and it is already tied up in a constitutional fight in Olympia. A conservative political-action committee has filed what it calls the first lawsuit against the law after the Secretary of State's office turned away its referendum paperwork, arguing the office quietly rewrote a key voter-protection clause. The challenge lands just as a 9.9% tax on income over 1 million dollars, passed by the Legislature this spring, is slated to start in 2028.
Let's Go Washington, a conservative PAC, says it went to court after the Secretary of State refused to accept its referendum filing, according to FOX 13 Seattle. At the center of the dispute is the office's use of a constitutional "necessity" clause that shields some laws from repeal at the ballot box. The group contends the state added the words "or for" when interpreting the clause, effectively splitting one exception into two and blocking a referendum. "If simply declaring something 'necessary' is enough to block a referendum, then there are effectively no limits," founder Brian Heywood told FOX 13. The lawsuit now asks the Washington Supreme Court to decide whether that reading of the constitution is legal.
What the law does and who it affects
Senate Bill 6346 applies a 9.9% tax to Washington taxable income that exceeds 1 million dollars and directs the money into the state general fund to support K-12 school meals, childcare programs and an expanded Working Families Tax Credit, according to the Washington State Legislature. Lawmakers approved the bill and the governor signed it at the end of March. Many provisions are set to take effect June 11, 2026, while the tax on income itself is scheduled to begin on January 1, 2028. Supporters argue the policy will ease Washington's reputation for regressive taxes and help fund services that primarily benefit working families and small businesses.
How challengers frame the constitutional question
In its complaint, Let's Go Washington says the Secretary of State's office changed the meaning of the constitution by inserting "or for" into the relevant passage, which the group argues expands a narrow exemption into a broader shield against referenda, according to FOX 13 Seattle. The Secretary of State's office told FOX 13 that its earlier letter to the PAC "was correct and based on decades of the Washington State Supreme Court's interpretation," and said courts have long treated the two clauses in question as separate bases for keeping a law off the ballot. The suit asks the high court to settle the matter now instead of waiting for a later election fight.
What comes next: petitions, timelines and court
Opponents still have tools to try to overturn the law at the ballot, but they are on the clock. A referendum must be filed within 90 days after lawmakers adjourn for the year, while an initiative can be filed later but requires more signatures, according to the Secretary of State's office. Under the current rules, both paths demand signatures in roughly the low hundreds of thousands, and campaigns typically aim higher to build a buffer for invalid signatures. Let's Go Washington has said it will pursue both the referendum and initiative routes as its lawsuit moves forward.
Why this matters in Washington
Supporters estimate the millionaire tax could bring in more than 3 billion dollars per year for schools, childcare and tax credits, according to reporting by Kiplinger. Critics counter that a top rate just under 10% could convince high earners and some businesses to take their money elsewhere, and that concern is already energizing the court challenge. For now, the fight plays out on two tracks: signature gathering across the state and a constitutional test that could end up in front of the Washington Supreme Court.
