FactHub curated dataset

Washington millionaires tax (ESSB 6346): official revenue estimates by fiscal year

Every official estimate of what Washington's 9.9% tax on income over $1 million (ESSB 6346, 2026) would raise, by state fiscal year: the Legislature's fiscal note, the Economic and Revenue Forecast Council's June and September 2026 forecasts, and OFM's fiscal impact statement for Initiative 645, plus how the enacted 2027-29 budget outlook counts the revenue and the campaign statements that cite these figures.

Coverage: State fiscal years 2026-2035 (July 1, 2025 - June 30, 2035); first collections April 2029 (FY2029).

Node: dataset:wa-millionaires-tax-revenue-estimates:1

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What this dataset measures

Initiative 645 (Nov. 3, 2026 ballot) would repeal the tax. Campaigns cite $11.4 billion, $13 billion and $300 billion for what repeal would cost. Those figures come from different estimates and different windows of years; this dataset puts every official estimate on the same fiscal-year basis so readers can see which window each figure covers.

Geography: Washington, United States
Unit of observation: One estimate of gross income-tax revenue for one state fiscal year.
Update cadence: Updated when ERFC issues a new revenue forecast (next: November 2026) or OFM issues a new fiscal note.
Curator: FactHub Research Team

Curated data tables

These related tables form this versioned dataset release. Each table has its own downloadable file and field definitions.

Gross income-tax revenue by fiscal year, by estimate

Each official estimate of gross collections from the 9.9% tax, by state fiscal year.

Unit of observation: One estimate for one state fiscal year

View this table

estimates_by_fy.csv text/csv · 3.4 KB (3,467 bytes)

8 field definitions

Field	Type	Meaning	Units	Value type
`estimate_id`	string	Short id of the estimate.	—	observed
`estimate_name`	string	Estimate and its publication month.	—	observed
`publisher`	string	Agency that published the estimate.	—	observed
`published_date`	date	Date the estimate was adopted or published.	—	observed
`fiscal_year`	integer	State fiscal year ending June 30 of this year.	year	observed
`gross_income_tax_musd`	number	Gross income-tax collections (before the 5% Fair Start transfer and before any offsetting tax relief).	millions of US dollars, cash basis	estimated
`value_type`	string	"observed" if printed in the source, "derived" if our calculation.	—	derived
`note`	string	Exact line in the source, or the calculation for a derived value.	—	observed

Fiscal note: gross income tax vs whole-bill net revenue

ESSB 6346 also cut sales and B&O taxes starting in 2029. Net state revenue is the gross income tax minus that relief (Working Families Tax Credit expansion is spending, not included).

Unit of observation: One state fiscal year

View this table

fiscal_note_net_vs_gross.csv text/csv · 333 bytes

4 field definitions

Field	Type	Meaning	Units	Value type
`fiscal_year`	integer	State fiscal year.	year	observed
`gross_income_tax_musd`	number	Fiscal note Tax on Income line (0 before FY2029).	millions of US dollars	estimated
`net_state_revenue_musd`	number	Fiscal note total state revenue impact of the whole bill.	millions of US dollars	estimated
`revenue_side_relief_musd`	number	Net minus gross: revenue given up through the bill's tax relief (negative).	millions of US dollars	derived

2027-29 budget outlook and the income tax

The enacted 2026 supplemental outlook's 2027-29 ending balance, what it counts from ESSB 6346, and the balance without it.

Unit of observation: One outlook line item

View this table

outlook_2027_29.csv text/csv · 796 bytes

4 field definitions

Field	Type	Meaning	Units	Value type
`item`	string	Outlook line or calculation.	—	observed
`value_musd`	number	Value.	millions of US dollars	estimated
`value_type`	string	"observed" or "derived" (our calculation).	—	derived
`source_id`	string	Source of the value.	—	observed

Supporting files

Source snapshots, manifests, quality reports, documentation, and other materials used to produce or review this release.

build.js Transformation manifest · text/javascript · 8.3 KB (8,539 bytes)
Node.js script that holds every input value with its source and writes the three tables and all saved-analysis results.
content-parts.json Documentation · application/json · 30.8 KB (31,561 bytes)
Sources, table definitions, saved analyses and statements of this release, as JSON (the same values the dataset page shows).

Saved analyses

Gross income-tax revenue by fiscal year, four official estimates

Question: How much does each official estimate expect the tax to collect in each fiscal year?

Result: First-year (FY2029) estimates range from $2.698 billion (fiscal note, ERFC June) to $3.503 billion (ERFC September); FY2030 from $3.732 billion to $5.032 billion.

Operation: Select estimates_by_fy rows; convert millions to billions.

Scope: All rows of estimates-by-fy.

View this analysis

Static projections; no collections yet.
OFM FIS rows are revenue loss to the general fund plus Fair Start, which equals gross collections.

Totals by estimate and window of years

Question: Which official estimate and window of years produce $11.4 billion, $12.9 billion and $13 billion?

Result: Fiscal note FY2029-32 (four years of collections): $12.894 billion. OFM FY2027-31: $11.432 billion. ERFC September FY2029-31 (three years of collections): $12.938 billion.

Operation: Sum gross_income_tax_musd over the fiscal years named in each window.

Scope: estimates-by-fy.

View this analysis

Windows differ in the number of collection years; compare like with like.

2027-29 outlook ending balance with and without the income tax

Question: What happens to the enacted budget outlook's 2027-29 balance if the income tax is removed?

Result: The outlook's +$0.653 billion 2027-29 balance becomes about -$2.0 billion if the gross income tax is removed and its relief stays (our calculation), or -$1.7 billion if the relief also goes.

Operation: Ending balance minus the amount the outlook counts from ESSB 6346 (net), and minus the gross income tax (relief kept, as under I-645).

Scope: outlook-2027-29.

View this analysis

The outlook is a projection made before the September forecast and before the 2027 Legislature writes the 2027-29 budget.
Ignores interactions such as lower DOR administrative costs (OFM: about $36 million in FY2029).

$300 billion compared with official estimates

Question: How does a $300 billion figure compare with each official estimate?

Result: $300 billion is 12.7 times the fiscal note's ten-year total and 23 to 31 times the three- and four-year estimates.

Operation: 300 divided by each window total in window-totals.

Scope: window-totals results.

View this analysis

No source has said what window or measure $300 billion refers to.

Fiscal note: tax relief bundled with the income tax, FY2029-32

Question: How much of the gross income tax does the bill's own revenue-side relief use up?

Result: Revenue-side relief is $0.35-0.83 billion a year, so net revenue is 77-87% of the gross tax. Under I-645 the relief stays, so the state loses the gross amount.

Operation: From fiscal-note-net-vs-gross: relief = gross - net; share = net / gross.

Scope: FY2029-2032.

View this analysis

Excludes the Working Families Tax Credit expansion, which is appropriated spending rather than a revenue reduction.

Statements on record

Exact quotes, unaltered, with what surrounded them, the primary source, and an archived copy of it.

This measure cuts funding for K-12 public schools, healthcare, childcare, and other important public services by $13 billion over four years.

Committee against I-645 (Janie White, WEA; April Sims, WSLC; et al.), Authors of the official voters' pamphlet argument against I-645 2026 General Election Voters' Pamphlet, Argument against · September 17, 2026 · Prediction

Context: Under the heading "Vote No: Stop Cuts to Schools, Healthcare, and Childcare." The next sentence says that means larger class sizes, higher costs for healthcare and childcare, "and the elimination of free school lunches for many children." The statement names no source or years for the $13 billion.

Source: 2026 General Election Voters' Pamphlet, Initiative Measure No. IP26-645, Washington Secretary of State

I-645 blows a $13 billion hole in the budget - don't believe lies that we can keep tax cuts for working families and small businesses but eliminate the tax on the wealthy few that pays for them.

Committee against I-645 (Janie White, WEA; April Sims, WSLC; et al.), Authors of the official voters' pamphlet rebuttal of the argument for I-645 2026 General Election Voters' Pamphlet, Rebuttal of argument for · September 17, 2026 · Prediction

Context: Closing lines of the No committee's rebuttal, after it says any expansion of the tax would be decided on the ballot.

Source: 2026 General Election Voters' Pamphlet, Initiative Measure No. IP26-645, Washington Secretary of State

This was never about schools or diapers, that's a scare tactic. Washington has record revenues.

Committee for I-645 (Sen. Chris Gildon, R-Puyallup, et al.), Authors of the official voters' pamphlet rebuttal of the argument against I-645 2026 General Election Voters' Pamphlet, Rebuttal of argument against · September 17, 2026 · Assertion

Context: The Yes rebuttal opens "The No campaign's claims are false. I-645 repeals the income tax," and argues that without I-645 the Legislature can expand the tax without a public vote.

Source: 2026 General Election Voters' Pamphlet, Initiative Measure No. IP26-645, Washington Secretary of State

Initiative 645 will cut $13 billion in funding…

No on 645 campaign, Committee opposing I-645 Campaign website no645.com (read October 21, 2026) · October 21, 2026 · Prediction

Context: A heading on the home page, followed by bullets: larger class sizes, increased health care costs, more child care cuts and elimination of free school meals. The page gives no source or years for the figure.

Source: No on 645 campaign home page

Working families already pay 3 times more than the top 1% in Washington. Now, millionaires and billionaires are trying to pass I-645, a ballot initiative that would give them a $300 billion tax break by cutting social programs in K-12 schools. Make it make sense.

Pramila Jayapal, U.S. Representative for Washington's 7th District Post on X from @PramilaJayapal · September 26, 2026 · Assertion

Context: Posted at 7:15 a.m. PDT on Sept. 26, 2026, with a link to the No on 645 YouTube ad "Some Things Work Better Upside Down," whose description calls I-645 "a 13 billion dollar tax break." As of Oct. 21, 2026 the post was still up, unedited, with no correction found from her account; her office gave no source for $300 billion in coverage we found.

Source: Post by Rep. Pramila Jayapal (@PramilaJayapal) on X, Sept. 26, 2026

They like to throw in K through 12, but our initiative doesn't do anything with K through 12 funding. So if they write K through 12, it is a lie, and we'll challenge it.

Brian Heywood, Founder of Let's Go Washington, sponsor of I-645 The Jason Rantz Show, Seattle Red 770 AM (as quoted by Seattle Red) · July 19, 2026 · Assertion

Context: Heywood was discussing the ballot's public investment impact disclosure before the Attorney General had written it, predicting it would mention K-12. The Attorney General's July 23 disclosure did name K-12; a judge upheld it and Let's Go Washington's own challenge was never heard.

Source: Heywood says I-645 fiscal impact statement is premature, vows court challenge, Seattle Red (July 19, 2026)

This initiative is an attempt by some of the richest people in our state, people making, by definition, over $83,000 a month, to cut $13 billion from K-12 education, from health care, and from higher education

Rian Watt, Economic Opportunity Institute, speaking for the No side KUOW Soundside interview · October 8, 2026 · Assertion

Context: Watt's opening case for a No vote, followed by Jaime Herrera Beutler's case for Yes in the same segment.

Source: The millionaires tax is on the WA ballot this fall. Both sides make their case, KUOW (Oct. 8, 2026)

Voting yes on Initiative 645 will not cut K-12 education funding, and it will not cut health care funding. This tax isn't even set to be collected until 2029.

Jaime Herrera Beutler, Spokesperson for the Yes on I-645 campaign KUOW Soundside interview · October 8, 2026 · Assertion

Context: Response to Rian Watt in the same segment. She added that lawmakers declined to earmark the money for health care and education.

Source: The millionaires tax is on the WA ballot this fall. Both sides make their case, KUOW (Oct. 8, 2026)

Sources

Multiple Agency Fiscal Note Summary, ESSB 6346 (2026), Tax on millionaires, OFM Fiscal Note package 77653 Fiscal note gross "Tax on Income" line and whole-bill net revenue by fiscal year, FY2026-2035.
Retrieved October 21, 2026. Public record (Washington State government work). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Government. Prepared by the Department of Revenue and published by the Office of Financial Management for the Legislature in March 2026. States its assumption that affected taxpayers do not reduce taxable income.
Fiscal Impact Statement for Initiative 645, Office of Financial Management (July 2026) Revenue lost by fiscal year if I-645 passes (Table 1).
Retrieved October 21, 2026. Public record (Washington State government work). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Government. Required by RCW 29A.72.025 and printed in the voters' pamphlet. Covers SFY2027-2031 only and excludes effects that depend on future legislative action.
Washington State Economic and Revenue Forecast, September 2026 (Vol. LXII, No. 3), Economic and Revenue Forecast Council Individual Income Tax 2027-29 biennium forecast, June and September (Table 3.7); General Fund-State detail by fiscal year (Table 3.9).
Retrieved October 21, 2026. Public record (Washington State government work). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Government. ERFC is the state's official, bipartisan revenue forecaster; its forecast is the legal basis for the state budget. Forecast adopted September 25, 2026.
Revenue Review, September 25, 2026, Economic and Revenue Forecast Council Fair Start for Kids Account forecast by fiscal year (5% of prior-year income-tax collections): FY2030 $175.2 million, FY2031 $251.6 million; June-to-September revisions.
Retrieved October 21, 2026. Public record (Washington State government work). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Government. Official ERFC presentation of the September 2026 revenue forecast.
Outlook for the Enacted 2026 Supplemental Omnibus Operating Budget (ESSB 5998), April 22, 2026, Economic and Revenue Forecast Council NGF-O projected ending balance by fiscal year and biennium.
Retrieved October 21, 2026. Public record (Washington State government work). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Government. The four-year balanced-budget outlook required by RCW 43.88.055, adopted by ERFC.
Enacted 2026 Supplemental Budget Outlook Methodology, April 22, 2026, Economic and Revenue Forecast Council Revenue legislation counted in the outlook (ESSB 6346: -$46,400 thousand in 2025-27, +$2,309,180 thousand in 2027-29); non-mandatory FY2029 expenditures for free school meals ($140 million) and city and county fiscal health ($200 million).
Retrieved October 21, 2026. Public record (Washington State government work). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Government. Methodology document accompanying the adopted outlook.
Revenues for 2025-27 and 2027-29 are still lower than expected when 2026 budget was adopted, but income tax revenue estimates are increased going forward, Washington Research Council (Sept. 25, 2026) September 2026 income-tax forecast by biennium ($3.503 billion 2027-29, $9.435 billion 2029-31) and change from June.
Retrieved October 21, 2026. All rights reserved (quoted under fair use). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Advocacy group. Business-funded nonpartisan research group that has published analysis critical of the income tax; here it only restates ERFC forecast figures, which match ERFC Table 3.7 for 2027-29.
New brief: I-645: Repealing the State Individual Income Tax, Washington Research Council (Sept. 22, 2026) States that no current appropriations rely on the revenue and that the current outlook assumes $2.698 billion of income-tax revenue in 2027-29.
Retrieved October 21, 2026. All rights reserved (quoted under fair use). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Advocacy group. Business-funded nonpartisan research group; it takes no position on I-645 in this brief.
2026 General Election Voters' Pamphlet, Initiative Measure No. IP26-645, Washington Secretary of State Arguments for and against I-645 and rebuttals, written by each campaign committee.
Retrieved October 21, 2026. Public record (Washington State government work). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Party to the dispute. Has a stake in this finding. The Secretary of State prints the statements as submitted; each argument is written by the committee for or against the measure and is not fact-checked by the state.
No on 645 campaign home page Campaign wording of the $13 billion claim.
Retrieved October 21, 2026. All rights reserved (quoted under fair use). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Party to the dispute. Has a stake in this finding. Official site of the committee opposing I-645, funded mostly by labor unions (PDC).
Post by Rep. Pramila Jayapal (@PramilaJayapal) on X, Sept. 26, 2026 Jayapal's "$300 billion tax break" statement. Free copy
Retrieved October 21, 2026. All rights reserved (quoted under fair use). Figures quoted with attribution; source file linked, not rehosted.

Reliability: Party to the dispute. Has a stake in this finding. Personal campaign account of the U.S. representative for WA-07, who opposes I-645. x.com blocks automated reading; the archived copy of X's own embed record shows the same text and that the post was not edited.
Heywood says I-645 fiscal impact statement is premature, vows court challenge, Seattle Red (July 19, 2026) Brian Heywood quoted on K-12 funding.
Retrieved October 21, 2026. All rights reserved (quoted under fair use). Figures quoted with attribution; source file linked, not rehosted.

Reliability: News report. Conservative talk-radio station website; quotes Heywood from an on-air interview on The Jason Rantz Show.
The millionaires tax is on the WA ballot this fall. Both sides make their case, KUOW (Oct. 8, 2026) Interview transcript excerpts with Rian Watt (No) and Jaime Herrera Beutler (Yes).
Retrieved October 21, 2026. All rights reserved (quoted under fair use). Figures quoted with attribution; source file linked, not rehosted.

Reliability: News report. Seattle public radio station (NPR member); edited transcript of its Soundside program.

Limitations and reproducibility

Reproducible: All inputs are printed in the linked government documents and typed into build.js, which writes every table and saved-analysis result. Derived values (ERFC per-year split, outlook balance without the tax) are computed in build.js with the method in each row note.

All estimates are static: they assume high earners do not change their behavior in response to the tax (the fiscal note says "affected taxpayers do not reduce taxable income").
No collections exist yet. The first payments are due in April 2029; every value is a projection.
ERFC publishes its income-tax forecast by biennium. The FY2030 and FY2031 split is our calculation from ERFC's 5% Fair Start for Kids transfers (5% of the previous fiscal year's collections), which ERFC publishes by fiscal year; rounding of the transfers to $0.1 million gives about +/- $2 million per year.
The September 2026 2029-31 income-tax total ($9,435 million) is as reported by the Washington Research Council; ERFC's own Table 3.9 corroborates it only within a combined "Other (including Individual Income Tax)" row.
OFM's fiscal impact statement counts revenue lost to the general fund plus the Fair Start for Kids account; it excludes $0.414 million of federal funds in FY2027-28 that this table leaves out.
The tax faces a constitutional challenge (Petter v. State, Klickitat County Superior Court, filed April 9, 2026). If courts strike it down, actual revenue would be zero with or without I-645.

Publications using this dataset

Version details

The exact citing versions, and the version of this dataset each cites.

Article i645-13-billion-no-current-cuts — version 5 (published) cites version 1
Article wa-millionaires-tax-net-increase — version 5 (published) cites version 1
Article jayapal-300-billion-tax-break — version 3 (published) cites version 1
Article wa-millionaires-tax-static-estimate — version 3 (published) cites version 1
Chart wa-millionaires-tax-revenue-estimates-by-fy — version 1 (published) cites version 1
Briefing wa-i-645 — version 6 (published) cites version 1
Briefing wa-i-645 — version 4 (published) cites version 1