Top state income tax rates in 2028, Washington's place among them, and effective rates for high-income households

What this dataset measures

Built to test whether Washington's 9.9% millionaires tax would be the highest, or among the highest, state income tax rates, and to show how marginal and average rates differ for the households that pay it.

Geography

United States, Washington, United States

Unit of observation

Jurisdiction; household income level and jurisdiction; tax component

Update cadence

Annually, when the Tax Foundation publishes its state rate table

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.

Top statutory state income tax rates, 2026 and 2028

The highest-rate jurisdictions plus Washington.

Unit of observation: Jurisdiction

View this table

top_rates.csv text/csv · 1.3 KB (1,339 bytes)

7 field definitions

Field	Type	Meaning	Units	Value type
jurisdiction	string	State or DC	—	observed
isState	boolean	False for the District of Columbia	—	observed
rate2026Pct	number	Top statutory rate in 2026	percent	observed
rate2028Pct	number	Top statutory rate scheduled for 2028 under law as of October 21, 2026	percent	observed
topBracketStartsMfj	number	Income at which the top rate starts for married couples filing jointly	US dollars of taxable income	observed
status	string	Where the figure was checked	—	observed
note	string	Caveats	—	observed

Effective state income tax for married couples with wages only

State income tax as a share of household income at three income levels.

Unit of observation: Household income level and jurisdiction

View this table

effective_rates.csv text/csv · 577 bytes

5 field definitions

Field	Type	Meaning	Units	Value type
householdIncome	number	Household wages	US dollars	estimated
incomeLabel	string	Label for the income level	—	derived
jurisdiction	string	State	—	observed
stateIncomeTax	number	State income tax owed	US dollars	derived
effectiveRatePct	number	Tax as a percent of household income	percent	derived

Tax Foundation's combined Seattle top marginal rate on wages

State and local taxes on an additional dollar of wages above $1 million in Seattle, as the Tax Foundation counts them.

Unit of observation: Tax component

View this table

seattle_combined.csv text/csv · 321 bytes

4 field definitions

Field	Type	Meaning	Units	Value type
component	string	Tax	—	observed
ratePct	number	Marginal rate	percent	observed
paidBy	string	Who remits it, and whether it is an income or payroll tax	—	observed
isIncomeTax	boolean	True only for the income tax	—	derived

Supporting files

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

• build_rates.js Transformation manifest · text/javascript · 6 KB (6,098 bytes)

  Node.js script holding every input and computing all tables.

Saved analyses

Sources

1. Tax Foundation Top rates and brackets for 2026

   Retrieved October 21, 2026. Tax Foundation content; facts transcribed. Rates transcribed as facts; not redistributed as a table copy

   Reliability: Advocacy group. Tax Foundation is a nonprofit that favors low, broad-based taxes; its annual state rate table is widely used as a reference. Its 2026 table lists Washington's top capital gains rate as 9%, which the Department of Revenue contradicts (9.9%).

2. Washington State Legislature Washington's 9.9% rate and $1 million household deduction from 2028

   Retrieved October 21, 2026. Public record of the Washington State Legislature. Public record

   Reliability: Government. Nonpartisan final bill report for ESSB 6346 (2026 c 238).

3. Massachusetts Department of Revenue Massachusetts 4% surtax threshold for 2026 ($1,107,750)

   Retrieved October 21, 2026. Public government information. Public record

   Reliability: Government. State revenue department; the surtax threshold is indexed annually under the state constitution.

4. Tax Foundation Components of the 18.037% combined Seattle top rate on wages

   Retrieved October 21, 2026. Tax Foundation content; facts transcribed. Figures transcribed as facts

   Reliability: Advocacy group. January 2026 analysis by a nonprofit that favors low, broad-based taxes; it counts employer-paid payroll taxes as falling on employees.

5. Washington State Department of Revenue Washington capital gains tax rates: 7% plus 2.9% on gains over $1 million

   Retrieved October 21, 2026. Public government information. Public record

   Reliability: Government. The agency that administers the capital gains tax.

Limitations and reproducibility

Reproducible: build_rates.js contains every input rate and bracket and recomputes all tables; inputs are transcribed from the sources listed.

• Statutory top marginal rates only; local income taxes (such as New York City's and Portland-area taxes) and payroll taxes are excluded from the ranking.
• Hawaii's reported increase to 13% from 2027 comes from news reports and was not checked against the statute; Washington's rank is the same whether Hawaii's top rate is 11% or 13%.
• Effective rates assume a married couple filing jointly with wages only and the standard deduction or exemption; real returns have other income, deductions and credits. California's 1.3% SDI payroll tax on wages is not included.
• Some 2026 bracket thresholds in the Tax Foundation table use 2025 inflation widths.
• The Seattle combined rate counts employer-paid payroll taxes as if workers bore them, which is the Tax Foundation's method, not a statement of who legally pays.