Ferguson Readies Washington Millionaires Tax, Senate Bill 6346 for Signoff

(WASHINGTON STATE) — Governor Bob Ferguson had not yet signed Washington’s millionaires tax bill as of March 30, 2026, leaving Senate Bill 6346 on track either for his signature in the coming days or to become law automatically afterward.

Lawmakers passed the measure on March 12, and Ferguson received it on March 13. He has until April 4, or up to April 6 in some reports, to act. If he does not sign it by then, the bill becomes law without his signature.

Ferguson has pledged to sign the measure. His office had not confirmed a signing on Monday.

Senate Bill 6346 would impose a 9.9% tax on Washington taxable income exceeding $1 million per household, with the threshold indexed for inflation. The tax would take effect on January 1, 2028, with first returns due in 2029 and estimated payments starting July 1, 2029, though those payments would be waived if liability is under $5,000.

The proposal would apply to residents, part-year residents and nonresidents with Washington-source income. It starts with federal adjusted gross income and then makes state modifications, including adding back state and local taxes deducted federally and applying a $1 million standard deduction, pro-rated for nonresidents.

Supporters expect the tax to affect about 30,000 households and raise about $4 billion annually. The money would go to the general fund for programs including health care, schools, an expansion of the Working Families Tax Credit, and child care, with 5% of revenue allocated to child care.

Ferguson has called the bill “historic” for affordability and said it applies to “<0.5% of people”. The measure has become one of the most closely watched tax debates in Washington, with backers framing it as a way to raise money from high-income households while opponents prepare for a political and legal fight.

The bill’s route through the Legislature was narrow and contentious. The Senate first passed it on February 16 by 27-22.

House members approved it on March 10 after a long and divisive debate, with reported vote counts of 51-46 or 52-46. In that chamber, 8 Democrats joined Republicans in opposition.

The Senate then concurred on March 12 after a 25-hour House debate, with reports listing the vote as 27-21 or 27-22. That final step sent the bill to Ferguson.

Alongside the income tax measure, lawmakers paired the package with Senate Bill 6347, which would revert the estate tax top rate to 20% from 35% for deaths on or after July 1, 2026. Senate Bill 6346 also includes an emergency clause that blocks a simple referendum.

That clause has sharpened the response from Republicans, who have said they will try to take the issue to voters another way. Washington State GOP Chair Rep. Jim Walsh, R-Aberdeen, announced plans for a repeal initiative aimed at the November 2026 ballot and said he would wait for Ferguson’s signature before filing it.

Walsh and other Republicans have focused on the state constitution’s uniformity requirement for taxes and on the prospect that a tax on very high incomes could open the door to broader income tax efforts later. Senate Republican Leader John Braun said organizations are preparing lawsuits over constitutional conflicts tied to taxing income at different rates.

Business groups have also opposed the measure, though from a different angle. Washington Roundtable and the Association of Washington Business have urged lawmakers to pursue sustainable budgeting instead of adopting the tax.

Their objections set up a battle that will likely move quickly once Ferguson acts. Opponents have signaled that even a signature would mark the start, not the end, of the fight over the millionaires tax.

Backers argue the bill aims narrowly at households above the $1 million threshold and leaves most Washington residents untouched. Ferguson’s description of the proposal as affecting “<0.5% of people” has become central to that message.

Public opinion figures cited by supporters and opponents point to a divided but not uniformly hostile electorate. Those figures show 71% of Democrats support the tax and 52% of independents support it, while 54% of Republicans oppose it, a contrast Republicans have tied to their argument that voters previously rejected state income tax proposals 11 times.

The practical shape of the tax is also broader than a simple wage levy. The bill would reach Washington-source income tied to business activity, investments and pass-through entities, extending beyond a narrow salary-based definition and pulling in part-year residents and some nonresidents.

That design matters for the fiscal assumptions behind the bill. Lawmakers and supporters have pointed to the estimated $4 billion annually in revenue as money that would support general fund spending and, in particular, programs tied to affordability.

One of the largest selling points has been the planned expansion of the Working Families Tax Credit. Supporters say that expansion would reach 460,000 more households.

They have also tied the bill to school funding, health care and child care. Under the measure, 5% of the revenue would be dedicated to child care.

Even so, the political sensitivity around any income-based tax in Washington has remained high for years, and opponents have moved quickly to cast Senate Bill 6346 as a constitutional test case. Braun’s warning that groups are preparing lawsuits reflects a long-running argument from critics that taxing income at different rates conflicts with state constitutional limits.

That challenge now hangs over the timeline for implementation. Although the tax would not take effect until January 1, 2028, legal action could start much sooner once the bill becomes law.

The measure’s filing and payment dates stretch the process farther out. Taxpayers affected by the levy would not file first returns until 2029, and estimated payments would begin on July 1, 2029, unless their liability falls below $5,000.

For now, the immediate focus remains on Ferguson’s desk. He received the bill on March 13 after the Legislature completed its work, and his next move will determine whether the tax arrives with an explicit signature or by the clock running out.

Either path would keep the substance of the law intact. The larger uncertainty lies in what follows from Republicans, business groups and organizations preparing to challenge the measure.

The bill’s supporters have tried to frame that coming fight around fairness and scale, arguing that a state with no broad personal income tax can ask more from the highest earners. Opponents have framed it as a constitutional overreach and a precedent that could widen later.

That split has shaped nearly every stage of the debate, from the close Senate tally on February 16 to the House vote on March 10 and the Senate concurrence on March 12. It also helps explain why even small discrepancies in reported deadlines and vote counts have not changed the larger picture: the Legislature sent the bill to Ferguson, and both sides are preparing for the next phase.

If Ferguson signs Senate Bill 6346, Washington will move toward a tax that supporters say would raise about $4 billion annually from roughly 30,000 households while funding health care, schools, tax credits and child care. If he leaves it unsigned past April 4, or April 6 in some reports, the measure becomes law anyway — and the legal fight opponents have promised can begin.