A Renton spa owner expects to move to Nashville by October. Seattle venture capitalist Nick Hanauer called the state's tax environment "a catastrophe" in a GeekWire op-ed.

However, a Cornell researcher who studied millions of tax returns says about 98% of Washington's wealthy will stay put.

Washington's 9.9% income tax on households earning more than $1 million a year does not take effect until 2028.

Voters will decide whether to kill it first. Initiative 645, which would repeal the tax and ban any future state or local income tax, is on the Tuesday, Nov. 3 ballot.

The tax debate has produced loud anecdotes on both sides. The data tell a quieter story.

Cornell University sociologist Cristobal Young, who co-authored national studies of high-earner tax returns, estimates the tax would cause a net loss of about 475 of Washington's 25,000 millionaire households. That is roughly 1.9%.

"There's going to be a handful that move. But 98% of millionaires are staying and paying that higher tax," Young told The Seattle Times.

Young's research found that each percentage-point increase in a state's top income-tax rate resulted in a net loss of less than 0.2% of millionaires. Six of the top 10 states for millionaire density, including California, New York and Massachusetts, impose high-earner income taxes.

State officials project a slight increase in Washington's millionaire population even after the tax takes effect. As of 2023, Washington had 6.2 millionaires per 1,000 taxpayers, compared with 5 per 1,000 nationally. In 2015, Washington was just below the national average of 3 per 1,000.

Still, individual stories carry political weight. Leslie Goeres, 37, owner of the Soak & Sage spa in Renton, told The Seattle Times she expects to move to Nashville by October.

She signed a lease for a second, 18,000-square-foot location there in February, before the tax passed in March. Goeres said the tax was what finally pushed her and her fiancé to leave a state where she has lived since 2011 and raised her two children. Tennessee has no income tax.

On the repeal side, Redmond hedge fund manager Brian Heywood, who founded Let's Go Washington and is sponsoring I-645, told KIRO Newsradio in July he has spent more than $10 million on various state initiatives.

He said he does not want to leave Washington but predicted the tax would drive others out.

Gov. Bob Ferguson signed the tax into law on March 30. The state Department of Revenue now estimates it will bring in $3.1 billion in its first fiscal year and roughly $8.3 billion in the 2029–31 biennium, according to the Washington State Standard.

Those figures are up from earlier projections of $2.7 billion and $6.9 billion. The money would fund K-12 schools, higher education and health care.

If voters approve I-645, the state estimates a revenue loss of $11.4 billion over fiscal years 2027–2031.

An Association of Washington Business (AWB) survey of 400 employers found nearly 1 in 4 were considering leaving the state, citing taxes as a top concern.

The AWB has endorsed I-645. Democrats in Olympia acknowledged some flight risk when they rolled back a sharp increase in the top estate tax rate during the recent legislative session.

Campaign spending is climbing. The No on 645 committees have raised a combined $5.2 million.

The pro-repeal side has raised $3.7 million. A July poll commissioned by the No on I-645 campaign showed 59% of respondents planned to vote against repeal.

The Department of Revenue is still building the enforcement system for the tax. At a Monday, Aug. 24 advisory-group meeting, Senior Assistant Director of Tax Policy Tim Jennrich called residency rules and related guidance "a significant lift." To avoid the tax, residents must document they have established residency in another state.

Most of the 25,000 households subject to the tax live in the Seattle area, with average annual incomes of $3.2 million.

Voters decide Nov. 3.