Washington state lawmakers have approved a proposal to introduce a tax on high-income residents after an extraordinary legislative debate lasting more than twenty-five hours, marking one of the most contentious fiscal votes in the state’s modern history.

The Washington House of Representatives passed the measure by a vote of fifty-one to forty-six following an overnight session that stretched from Monday evening into Tuesday night.

Four members of the Democratic majority joined Republicans in opposing the proposal, highlighting deep divisions within the chamber over the future of the state’s tax system.

The legislation, widely described by supporters as a “millionaires tax,” would impose a nine point nine percent levy on household income above one million dollars per year.

Lawmakers estimate the policy would affect roughly twenty thousand high-income households across the state and eventually generate about three billion dollars annually once fully implemented.

Supporters argue the tax would help address structural gaps in Washington’s public finances while providing funding for education, healthcare, housing and public safety.

Some of the revenue would also be used to offset existing taxes and support childcare and other social programs.

Opponents countered that the proposal risks undermining the state’s economic competitiveness and could face legal challenges under Washington’s constitution, which has historically treated income as a form of property subject to strict taxation rules.

Critics also warned that once established, the tax could expand to affect a broader portion of residents.

The bill had already cleared the state Senate earlier in the legislative session after several hours of heated debate, and it now returns to that chamber for approval of amendments made in the House before it can be sent to Governor Bob Ferguson for consideration.

Washington is one of the few U.S. states that does not currently impose a broad personal income tax, relying instead on sales taxes and business levies to generate revenue.

Previous attempts to introduce income taxes have repeatedly been rejected by voters and courts, making the latest proposal a significant test of longstanding political and legal barriers.

The extended debate in the House included more than eighty proposed amendments and periods of rest for lawmakers as the session stretched through the night.

The final vote came just days before the end of the legislative session, concluding one of the most dramatic floor battles of the year.

If enacted and ultimately upheld in court, the policy would represent the first statewide tax on personal income in Washington’s history and could reshape the state’s fiscal framework for decades to come.