Washington millionaires tax: who files over $1 million, how the threshold holds up, and how volatile the base is

What this dataset measures

These tables test how far the 9.9% tax on household income over $1 million (ESSB 6346, chapter 238, Laws of 2026) reaches beyond the households that pay it: how many filers sit above the line, how much their income swings from year to year, how the comparable capital gains tax has performed, and whether the $1 million threshold keeps its value over time.

Geography

Washington State

Unit of observation

Varies by table: tax year (IRS, capital gains), estimate (households), tax year by inflation scenario (threshold)

Update cadence

Ad hoc; update when IRS SOI releases tax year 2023 state data or the Department of Revenue publishes guidance on the standard-deduction adjustment

Curator

FactHub

Curated data tables

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

Washington returns with AGI of $1 million or more, 2019-2022

One row per tax year from the IRS SOI state file, AGI class 10 ($1,000,000 or more), compared with all Washington returns.

Unit of observation: Tax year

View this table

wa_irs_returns_1m_plus.csv text/csv · 345 bytes

9 field definitions

Field	Type	Meaning	Units	Value type
taxYear	integer	Federal tax year	—	observed
allReturns	integer	All Washington returns (N1, AGI_STUB 0)	returns	observed
returns1mPlus	integer	Returns with AGI of $1,000,000 or more (N1, AGI_STUB 10)	returns	observed
shareOfReturnsPct	number	returns1mPlus as a percent of allReturns	percent	derived
agi1mPlusBillion	number	Total AGI of $1M+ returns (A00100, thousands of dollars, divided by 1e6)	billion dollars	derived
shareOfAgiPct	number	AGI of $1M+ returns as a percent of all Washington AGI	percent	derived
wages1mPlusBillion	number	Salaries and wages on $1M+ returns (A00200)	billion dollars	derived
netCapitalGain1mPlusBillion	number	Net capital gain (less loss) on $1M+ returns (A01000)	billion dollars	derived
partnershipSCorp1mPlusBillion	number	Partnership and S corporation net income (less loss) on $1M+ returns (A26270)	billion dollars	derived

Real value of the $1 million standard deduction, 2028-2050

The deduction as section 316 of ESSB 6346 adjusts it (each October of odd years from 2029, by one 12-month CPI change) and, for comparison, as it would be if adjusted every year like the capital gains deduction, expressed in 2026 dollars.

Unit of observation: Tax year and inflation scenario

View this table

threshold_real_value.csv text/csv · 2.6 KB (2,694 bytes)

6 field definitions

Field	Type	Meaning	Units	Value type
inflationPct	number	Assumed constant annual CPI-W inflation	percent	estimated
taxYear	integer	Tax year the deduction applies to	—	observed
nominalAsWritten	integer	Deduction under section 316 as written	dollars	derived
realAsWritten2026	integer	nominalAsWritten in 2026 dollars	2026 dollars	derived
nominalAnnualIndex	integer	Deduction if adjusted every year from tax year 2029	dollars	derived
realAnnualIndex2026	integer	nominalAnnualIndex in 2026 dollars	2026 dollars	derived

Washington capital gains tax collections by tax year

Net payments (payments less refunds) as reported by the Department of Revenue on June 9, 2026.

Unit of observation: Tax year

View this table

wa_capital_gains_collections.csv text/csv · 183 bytes

4 field definitions

Field	Type	Meaning	Units	Value type
taxYear	integer	Tax year	—	observed
netCollectionsMillion	number	Net collections	million dollars	observed
netPayments	integer	Number of net payments	payments	observed
status	string	observed, or initial for tax year 2025	—	observed

Share of Washington households expected to pay

Each official estimate of paying households divided by the ACS 2024 household count.

Unit of observation: Estimate

View this table

paying_household_share.csv text/csv · 189 bytes

4 field definitions

Field	Type	Meaning	Units	Value type
estimate	string	Which estimate	—	observed
payingHouseholds	integer	Estimated households owing the tax	households	estimated
waHouseholds	integer	All Washington households, ACS 2024 1-year	households	estimated
sharePct	number	payingHouseholds as a percent of waHouseholds	percent	derived

Supporting files

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

• results.json Derived table · application/json · 20.4 KB (20,936 bytes)

  Saved-analysis result rows (chart-ready) generated from the CSV tables

• build_data.js Transformation manifest · text/javascript · 4.9 KB (4,974 bytes)

  Node.js script that extracts the IRS rows and computes the threshold projection (run: node build_data.js <folder with IRS files saved as in19.csv-in22.csv>)

Saved analyses

Sources

1. IRS Statistics of Income, Individual Income Tax State Data, tax year 2022 (22in55cmcsv.csv) Washington returns and income by AGI class, tax year 2022

   Retrieved October 14, 2026. Public domain (U.S. government work). Unrestricted; linked, not rehosted

   Reliability: Government. The IRS Statistics of Income division tabulates every individual return filed, by state and AGI class. It takes no position on Washington's tax.

2. IRS Statistics of Income, Individual Income Tax State Data, tax year 2021 (21in55cmcsv.csv) Washington returns and income by AGI class, tax year 2021

   Retrieved October 14, 2026. Public domain (U.S. government work). Unrestricted; linked, not rehosted

   Reliability: Government. The IRS Statistics of Income division tabulates every individual return filed, by state and AGI class. It takes no position on Washington's tax.

3. IRS Statistics of Income, Individual Income Tax State Data, tax year 2020 (20in55cmcsv.csv) Washington returns and income by AGI class, tax year 2020

   Retrieved October 14, 2026. Public domain (U.S. government work). Unrestricted; linked, not rehosted

   Reliability: Government. The IRS Statistics of Income division tabulates every individual return filed, by state and AGI class. It takes no position on Washington's tax.

4. IRS Statistics of Income, Individual Income Tax State Data, tax year 2019 (19in55cmcsv.csv) Washington returns and income by AGI class, tax year 2019

   Retrieved October 14, 2026. Public domain (U.S. government work). Unrestricted; linked, not rehosted

   Reliability: Government. The IRS Statistics of Income division tabulates every individual return filed, by state and AGI class. It takes no position on Washington's tax.

5. IRS SOI Tax Stats - Historic Table 2 (state data documentation) Field definitions for the state files (AGI_STUB 10 = $1,000,000 or more; N1, A00100, A00200, A01000, A26270)

   Retrieved October 14, 2026. Public domain (U.S. government work). Unrestricted

   Reliability: Government. IRS documentation of the field codes and AGI classes used in the state data files.

6. Washington State Legislature, ESSB 6346 as enacted (chapter 238, Laws of 2026) Sections 314 and 316: the $1,000,000 standard deduction and its inflation adjustment; section 1(9): the legislative estimate of who pays

   Retrieved October 14, 2026. Public domain (Washington State law). Unrestricted

   Reliability: Government. Official text of Washington law published by the Legislature's Code Reviser. The Legislature enacted the tax, but the text itself is the authoritative statement of what the law says.

7. RCW 82.87.150, capital gains tax inflation adjustments Comparison: the capital gains standard deduction is adjusted every October by the 12-month CPI change

   Retrieved October 14, 2026. Public domain (Washington State law). Unrestricted

   Reliability: Government. Official text of Washington law published by the Legislature's Code Reviser. The Legislature enacted the tax, but the text itself is the authoritative statement of what the law says.

8. RCW 82.87.040, capital gains tax rates The 2025 additional 2.9% rate on Washington capital gains over $1,000,000, a threshold RCW 82.87.150 does not adjust

   Retrieved October 14, 2026. Public domain (Washington State law). Unrestricted

   Reliability: Government. Official text of Washington law published by the Legislature's Code Reviser. The Legislature enacted the tax, but the text itself is the authoritative statement of what the law says.

9. Washington Department of Revenue, Capital Gains Tax - Tax Year 2025 Initial Collections Net capital gains tax collections and payment counts, tax years 2022-2025, as of June 9, 2026

   Retrieved October 14, 2026. Public domain (Washington State government work). Unrestricted

   Reliability: Government. The Department of Revenue administers the capital gains tax and reports collections from returns and payments. Figures are revised as refunds and amended returns arrive.

10. U.S. Census Bureau, American Community Survey 2024 1-year, table B11001 (Household Type), Washington Total Washington households: 3,168,080 (margin of error plus or minus 9,393)

    Retrieved October 15, 2026. Public domain (U.S. government work). Unrestricted

    Reliability: Government. The Census Bureau's American Community Survey estimates household counts from an annual sample; the 2024 one-year estimate has a stated margin of error.

11. Washington State Standard via The Inlander, 'WA revenue officials: Income tax will bring in more money than first expected' (Aug. 27, 2026) Department of Revenue household estimates: 21,000 (legislative fiscal note) and 25,000 (July 2026 revision)

    Retrieved October 14, 2026. News article; cited, not redistributed. Link only

    Reliability: News report. Washington State Standard reporting, republished by The Inlander, of Department of Revenue estimates presented to lawmakers. A secondary report of official figures.

Limitations and reproducibility

Reproducible: build_data.js reads the four public IRS SOI state files and regenerates every CSV; the capital gains and household figures are typed from the cited Department of Revenue page and Census table, and the threshold projection is computed by the same script from the formula in ESSB 6346 section 316.

• IRS counts are tax returns, not households; a married couple filing jointly is one return, but two single earners in one household are two returns. The tax applies per household, so return counts are only an approximation of the payer count.
• IRS adjusted gross income includes long-term capital gains, which the millionaires tax removes and replaces with Washington capital gains already taxed under chapter 82.87 RCW; the $1 million AGI class is therefore not identical to the tax's base.
• The threshold projection assumes a constant inflation rate (2%, 2.5% or 3%) and reads section 316 literally: an October adjustment in each odd year from 2029, equal to the 12-month CPI-W change, applying to that tax year. The Department of Revenue had issued no guidance interpreting section 316 as of October 2026, and section 314 calls the adjustment annual, so the department or a later Legislature could apply it differently.
• Tax year 2025 capital gains collections are initial figures as of June 9, 2026, rounded by the department to $1.5 billion.
• The household share uses the ACS 2024 one-year household count (3,168,080, margin of error plus or minus 9,393) for both payer estimates, although the tax begins in 2028.