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Blog / State & Local Tax / Washington’s Millionaire Tax Heads to the Ballot: What Comes Next for High Earners

State & Local Tax

Washington’s Millionaire Tax Heads to the Ballot: What Comes Next for High Earners

August 6, 2026
Andrea Potter

Article | by Geffen Mesher

When Governor Bob Ferguson signed Senate Bill 6346 into law in March 2026, Geffen Mesher noted in a prior article that legal challenges and a potential ballot referendum were both likely. That referendum is now a reality. Initiative 645, a measure to repeal Washington’s new 9.9% tax on income above $1 million, has formally qualified for the November ballot after collecting enough signatures to meet the threshold set by the Washington Secretary of State.

The repeal effort is being led by Let’s Go Washington, a political action committee supported by hedge fund manager Brian Heywood. Supporters of the initiative argue that the new law opens the door to a broader statewide income tax, while proponents of the tax counter that it affects only a small fraction of Washington households and point to its potential to address state budget shortfalls.

Supporters of the tax have also attracted significant financial and political support.

At the same time, a separate legal challenge is working its way through the courts, arguing that income constitutes property under Washington law and that the tax therefore violates constitutional limitations on property taxation. That argument echoes challenges that have historically derailed previous income tax efforts in the state.

What does this mean for Washington residents and business owners who may be affected? For now, the 9.9% tax is still scheduled to take effect in 2028, with the first taxes due in 2029. But with both a voter referendum and active litigation in play, the ultimate outcome remains uncertain. Key developments are expected in the coming months, and Geffen Mesher will continue to monitor developments closely.

In the meantime, uncertainty is not a reason to wait. High-income taxpayers whose earnings regularly exceed or approach the $1 million threshold should begin evaluating how SB 6346 could affect their overall tax position. Early planning may help identify opportunities related to income sourcing, residency considerations, entity structure, and the timing of significant transactions. This is particularly important for business owners with pass-through income, individuals with multistate activities, such as taxpayers with connections to both Oregon and Washington.
Geffen Mesher’s State and Local Tax (SALT) team will continue to monitor legislative, judicial, and ballot developments related to SB 6346. Taxpayers potentially affected by the new law should consider evaluating their current situation well before the tax’s scheduled effective date. For assistance assessing potential exposure, planning opportunities, or multistate tax implications, contact a Geffen Mesher advisor or visit GMCO.com.

Geffen Mesher’s team is available to assist you with questions related to these updated rules. Please contact professionals for more information at INFO@GMCO.COM.

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