Washington’s newly enacted income tax targeting high-earning residents may not officially take effect until 2028, but it has already ignited a storm of legal challenges, legislative maneuvers, and political pushback across the state. Even as the policy sits years away from implementation, a date has formally been set for oral arguments in a high-stakes constitutional challenge. Meanwhile, the debate has intensified following a recent proposal by a state lawmaker to dramatically lower the tax threshold to $250,000, and voters are preparing to weigh in directly this November through a ballot measure known as Initiative 645, which seeks to repeal the legislature’s decision and block the tax from ever taking effect.

The path that brought Washington to this legislative crossroads involves a complex series of procedural steps and political positioning. In early 2024, the state legislature overwhelmingly approved a ballot measure that had been filed by petitioners. Rather than allowing the measure—which stipulated that neither the state nor any county, city, or local jurisdiction could tax individuals on personal income—to go before voters, lawmakers adopted it directly.

This move was largely procedural. Under state law, amending language adopted directly by a ballot measure requires a two-thirds legislative supermajority for the first two years. Had the measure gone to the ballot and been approved by voters in November 2024, lawmakers would have been constitutionally barred from considering an income tax until the 2027 legislative session. By taking the initiative off the ballot and enacting it themselves in early 2024, lawmakers started the legislative clock sooner. This maneuver enabled them to return during the 2026 session and do precisely what the original citizen measure sought to prohibit: adopt a targeted income tax on high earners.

To further shield their legislative actions from public pushback, Washington lawmakers employed another procedural mechanism. They attached an emergency clause to the high-earner income tax legislation, asserting that the new revenue measure—despite not taking effect until 2028, with initial tax filings due in 2029—was immediately necessary for the support of state government and its existing public institutions.

This classification effectively insulated the measure from a provision in Washington law that ordinarily grants voters the right to review tax changes through a referendum. With that traditional avenue of opposition blocked, tax opponents responded by filing their own independent initiative for the ballot. That measure, Initiative 645, successfully qualified and will face voters this November.

The controversy surrounds a state that historically had no broad-based income taxation, with a state constitution that previous judicial interpretations largely viewed as prohibiting income taxes altogether—a central question in the pending litigation. Under the newly designed structure, some high earners residing in Seattle could face a combined state and local top tax rate reaching 18.037 percent, split between employers and employees. This staggering figure combines the state’s new 9.9 percent income tax with Seattle’s 5 percent Social Housing Tax, the 2.557 percent Seattle JumpStart Tax, and the 0.58 percent WA Cares state payroll tax.

The tax applies specifically to individuals or married couples reporting incomes exceeding $1 million. Consequently, its financial impact will fall predominantly on small business owners, high-compensated technology sector workers, and residents experiencing specific liquidity events. Very few W-2 wage earners earn base salaries surpassing $1 million annually. Instead, incomes at that magnitude typically flow through three primary channels: capital gains and dividend income, pass-through business earnings, and restricted stock unit vesting events.

The mechanism of restricted stock units (RSUs) is expected to draw many middle-class or upper-middle-class tech employees unexpectedly into the high-earner tax bracket. When a privately held startup goes public, employees may experience years of accumulated stock vesting simultaneously. An individual might work at a growing enterprise for five years, only for all five years of accumulated stock shares to vest at once during an initial public offering. This single event can push their annual income well above the $1 million threshold, even though their average earnings over those five years remained far below that level.

Beyond tech employees, the policy directly impacts pass-through businesses, which include sole proprietorships, partnerships, and S corporations. According to data from the U.S. Small Business Administration, Washington is home to more than 672,000 small businesses, the vast majority of which operate as pass-through entities. These small businesses employ approximately 1.4 million workers, accounting for 48.4 percent of all private-sector employment in the state.

Critics argue that imposing a 9.9 percent income tax on small business owners establishes one of the nation’s highest tax burdens on pass-through income. This burden arrives in a state that already levies a high-rate gross receipts tax—known as the Business and Occupation Tax—and subjects an unusually broad share of business inputs and transactions to the state sales tax.

Washington’s broader tax architecture has long leaned heavily on business-level taxation, largely because the state has traditionally avoided a broad-based individual income tax. Unlike other states operating without an individual income tax, however, Washington has not cultivated a low-tax, limited-government fiscal philosophy. This combination forces businesses to shoulder a disproportionate share of the overall public revenue burden. By layering a high-rate income tax exclusively on high earners, critics contend the state has engineered an unfavorable environment for small business owners, constraining their capacity for expansion and dampening long-term job creation.

In addition to tech workers with vesting RSUs, other residents could find themselves unexpectedly swept into the tax net during anomalous financial years. Individuals who sell a small business they spent decades building, or those who realize significant capital gains from selling a primary residence or real estate holdings, may cross the $1 million threshold during a single tax year.

The structural design of the tax has also drawn scrutiny from tax policy experts for several unusual provisions. The state’s new tax features a charitable deduction capped at $50,000. Additionally, joint filers face taxation on income above $1 million under the exact same parameters as single filers. Under this rule, two single individuals earning $600,000 each would incur zero tax liability, whereas a married couple with the exact same combined income filing jointly would be subject to the tax.

Furthermore, the framework lacks any safe harbor provisions for taxpayers who unexpectedly cross the income threshold due to unforeseen financial events. Under federal tax law and the statutes of most other states, underpayment penalties are waived if taxpayers remit at least 90 percent of their current year’s liability or 100 to 110 percent of their prior year’s liability through periodic withholding or quarterly estimated payments. Washington’s new statute contains no such safe harbor, meaning taxpayers who fail to anticipate their liability or misjudge their financial standing could face severe penalties.

Overturning the new tax via the ballot box presents a formidable political challenge. Opponents face an uphill battle exacerbated by contested ballot wording. State law permits the attorney general to supply a fiscal impact statement for ballot measures, and the statement attached to Initiative 645 warns voters that repealing the tax would necessitate immediate cuts to education funding. Critics of the official language note that it warns of funding reductions despite the tax not yet being in effect and no legislative budget having incorporated those speculative future revenues.

Nevertheless, as lawmakers actively discuss proposals to expand the tax to lower-income thresholds even before the initial policy takes effect, many voters may lean toward a familiar precedent. Historically, Washington voters have repeatedly rejected efforts to establish an income tax, and the upcoming electoral and legal battles will determine whether that long-standing trend holds.