Washington Braces for Legal and Ballot Battles Over New Income Tax

Opponents of the 9.9% tax on households with incomes above $1 million are preparing legal challenges and ballot measures to overturn the new law.

Mar. 29, 2026 at 2:14am

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Washington state is expected to enact a new 9.9% income tax on households earning over $1 million per year starting on Monday. However, opponents are already gearing up for a legal fight to challenge the law's constitutionality, as well as potential ballot measures to repeal it through the initiative process. The battle lines are being drawn as supporters celebrate the tax's passage while bracing for a lengthy legal and political battle ahead.

Why it matters

Washington has been one of only nine states without a state income tax, making this new law a major shift. The fight over the tax's implementation will test the state's political landscape, with Democrats in power but facing a potentially energized conservative electorate in future elections.

The details

Opponents are expected to quickly file a lawsuit challenging the constitutionality of the new income tax law, citing a 1933 state Supreme Court ruling that struck down a previous income tax. The plaintiffs in this lawsuit are likely to be small business owners, tech entrepreneurs, and others affected by the tax, rather than high-profile millionaires. There may also be efforts to remove the 'necessity clause' that shields the law from a referendum. If successful, that would allow opponents to try to repeal the tax through a ballot measure this November, though the timeline would be extremely tight. Alternatively, opponents could wait until 2027 to pursue an initiative to the legislature, which would give them more time but risk losing momentum.

  • The new income tax law is expected to be signed by Gov. Bob Ferguson on Monday, March 30, 2026.
  • If opponents pursue a ballot measure this year, they would need to collect and submit around 400,000 voter signatures by July 2, 2026 to qualify for the November 2026 ballot.
  • If opponents wait until 2027, they would have until the end of this year to collect 308,911 signatures for an initiative to the legislature.

The players

Rob McKenna

A former state attorney general and 2012 Republican candidate for Washington governor, who is among those formulating the legal arguments against the new income tax law.

Brian Heywood

The founder of the political committee Let's Go Washington, which has qualified nine initiatives in the past three years and is advocating for an immediate ballot measure to repeal the income tax.

Jim Walsh

The chair of the Washington State Republican Party, who says opponents should 'strike while the iron is hot' and pursue a ballot measure this year rather than waiting until 2027.

Sandeep Kaushik

A partner with the Seattle-based political consulting firm Sound View Strategies, who believes the political environment will favor Democrats in 2026 and that opponents should wait until 2027 to pursue a ballot measure.

Peter Graves

An advisor to business groups and Republican candidates, who says opponents should run an anti-income tax measure 'every year until it's off the table for good.'

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What they’re saying

“There's a legal fight and a public relations battle shaping up on day one. The signing of the bill is just the start of it.”

— Sandeep Kaushik, Partner, Sound View Strategies

“It's crazy to wait. The issue is on people's minds now. We should strike while the iron is hot.”

— Brian Heywood, Founder, Let's Go Washington

“We should run an anti-income tax measure every year until it's off the table for good.”

— Peter Graves, Advisor to business groups and Republican candidates

What’s next

The judge in the expected lawsuit challenging the constitutionality of the new income tax law will decide whether to allow the law to take effect as planned or issue an injunction while the case is pending.

The takeaway

The battle over Washington's new income tax law is shaping up to be a high-stakes political and legal fight, with opponents determined to overturn the legislation through the courts and the ballot box. The outcome will have major implications for the state's fiscal future and political landscape.