For almost a century, Washington's appeal to high earners has rested on a single, simple fact: no state income tax. That changed on March 30, 2026, when Governor Bob Ferguson signed ESSB 6346 — a 9.9% tax on household income above $1 million per year. The tax takes effect on January 1, 2028, with first payments due in 2029.
This guide is written for the people it actually affects: founders approaching a liquidity event, executives with RSU vesting cliffs, investors with concentrated gains, and the advisors trying to help them plan. It explains what the law does, what it doesn't do, how it interacts with Washington's existing capital gains and estate taxes, and the specific planning moves still available during the 20-month runway to the effective date.
A word of caution up front. ESSB 6346 is already in active constitutional challenge (Klickitat County Superior Court, filed April 9, 2026, by a legal team that includes former Attorney General Rob McKenna and former Supreme Court Justice Phil Talmadge). The challenge relies on Culliton v. Chase, the 1933 decision that invalidated a prior Washington income tax as an unconstitutional property tax. Prudent planning assumes the law stands. Hoping for litigation is not a plan.
The basics: what ESSB 6346 actually does
Three numbers capture the law:
- 9.9% — the flat rate.
- $1,000,000 — the household threshold below which no tax applies.
- 2028 — the effective date; first tax year is 2028, first returns due 2029.
Mechanically, the tax is imposed on Washington taxable income, which begins with the taxpayer's federal adjusted gross income (Form 1040, line 11), applies certain state-specific modifications, and subtracts a $1 million household exemption. Only the income above that exemption is taxed, and only at the 9.9% rate. There is no graduated bracket structure and no higher rate at the top.
The revenue projection is roughly $3 to $3.5 billion per year, drawn from an estimated 21,000 Washington households — less than 1% of the population. This is deliberately a tax on concentrated wealth, not a broad middle-class levy.
Who this actually hits
The $1 million AGI threshold sounds high until you consider the kinds of income that push a household over it in a single year:
- Founders and early employees realizing gain on a sale, IPO, tender offer, or secondary.
- Executives with RSUs that vest in concentrated cliffs or with large ISO exercises and disqualifying dispositions.
- Investors exiting concentrated positions — public stock, crypto, real estate, private fund distributions.
- Professional services partners with high-income years driven by partnership distributions.
- Retirees with large IRA/401(k) distributions, Roth conversions, or appreciated asset sales.
Many of these people do not think of themselves as "millionaires" — they think of themselves as having a big year. ESSB 6346 does not care about that distinction. It taxes a year, not a net worth.
The marriage penalty
The threshold is per household, not per spouse. A married couple earning $700,000 each pays tax on $400,000 of combined income; two unmarried individuals with the same $700,000 each pay nothing. The difference is roughly $39,600 of annual state income tax liability, triggered solely by the marital status.
This structural feature will become the most controversial element of the tax for many high-earning households. For couples approaching a big year, it is also one of the rare planning issues where timing of the event — and in some cases timing of the marriage — can move real money. We cover the structural marriage penalty and planning implications in a separate guide: The Marriage Penalty in ESSB 6346.
Does QSBS escape the Washington income tax?
The short answer is generally yes, because the tax base is federal AGI. Section 1202 of the Internal Revenue Code excludes qualified small business stock gain from gross income entirely (subject to the per-issuer cap). Excluded QSBS gain never enters federal AGI, which means it never enters the Washington base.
This makes the QSBS exclusion extraordinarily valuable for Washington residents after 2028. A founder with $10 million of §1202-qualified gain saves not only the federal capital gains tax, but the incremental 9.9% Washington income tax — about $900,000 on a single $10 million exit in excess of the threshold. We cover the mechanics and the timing pitfalls in QSBS and Washington Residency: Timing the §1202 Hold.
The caveat: gain that does not qualify for §1202 (too short a hold, wrong entity type, disqualified stock) flows straight into AGI and counts toward the $1M threshold. Founders with partial §1202 qualification need careful planning; all-or-nothing thinking loses real money here.
Interaction with Washington's 7% capital gains tax
Washington's capital gains tax (RCW 82.87) has been in force since 2022 and imposes a 7% tax on long-term capital gains in excess of a standard deduction (currently $270,000 for 2024 tax year, indexed). That tax is not going away. It now sits alongside ESSB 6346, not instead of it.
For Washington residents, a 2028+ liquidity event involving large non-QSBS long-term capital gain will potentially be subject to both:
- The 7% capital gains tax on the gain itself (subject to the standard deduction and §1202 conformity), and
- The 9.9% income tax on the AGI attributable to that gain, to the extent total household AGI exceeds $1 million.
The two taxes have different bases, different exemptions, and different sourcing rules. The interaction is not clean double-taxation in every case, and the Department of Revenue has not yet issued implementing rules on how the two systems coordinate. But as a planning matter, you should assume the effective marginal state tax rate on 2028+ capital gains for a high-earning Washington resident could exceed 16% on a non-QSBS disposition — roughly competitive with New York and California.
The estate tax context (why this matters for domicile)
Washington also has one of the most aggressive estate taxes in the country. The exemption is $2.193 million (substantially below the federal exemption), and the top rate is 20%. For an estate of $25 million, the Washington estate tax bill can exceed $4 million — entirely separate from any federal estate tax.
We mention this because once a high-earner is actively considering domicile change to avoid ESSB 6346, the estate tax calculus moves in the same direction. For many households, the estate tax savings from leaving Washington will exceed the income tax savings by an order of magnitude. The domicile strategy guide covers this in depth.
The planning window: what to do between now and 2028
There are essentially four planning responses to ESSB 6346, and most high-earners will combine more than one.
1. Accelerate recognition into 2026 or 2027
Income recognized before January 1, 2028 is not subject to ESSB 6346. For taxpayers with discretion — secondary sales, Roth conversions, deferred comp distributions, installment note prepayments, equity grant exercises — the pre-effective-date window is a real opportunity. The trade-off is federal tax liability and potential capital gains tax exposure, which in many cases dominates the analysis. But "income that doesn't exist yet" is easier to shift than "income already on the books."
2. Change domicile before the liquidity event
The most powerful option, and the most procedurally complex. Domicile change is a facts-and-circumstances determination; a cleanly executed move can remove the taxpayer from Washington's income tax jurisdiction entirely. The full playbook is in How to Leave Washington Before the Income Tax Hits, with supporting guides on domicile versus residency, the 183-day rule and day-counting, and where to move.
3. Structure around the tax with trusts and entities
Non-grantor trusts sitused outside Washington (ING, NING, DING structures in Nevada, South Dakota, or Delaware) can shift investment income out of a Washington resident's AGI. These structures are legal but under active IRS scrutiny, and they work best when paired with — not instead of — a personal domicile change. See Trust Planning for Washington High Earners.
4. Qualify the underlying income differently
QSBS qualification, §1031 exchanges, installment sales, opportunity zone investments, and charitable planning all shift the federal treatment and therefore the Washington treatment. These are federal-first analyses with Washington benefits flowing through.
What not to do
- Do not wait for the litigation. Klickitat County courts will not resolve this in time to affect 2027 planning, and a Supreme Court appeal likely stretches into 2028 or beyond.
- Do not "move on paper." A change-of-address form is not a change of domicile. Washington DOR will audit, and the audit will be document-intensive.
- Do not over-rely on trusts as a substitute for personal planning. Trusts can supplement domicile strategy; they rarely replace it.
- Do not assume the rules are final. DOR has not yet issued implementing regulations. Expect refinements on sourcing, partial-day residency, and trust treatment over the next 18 months.
The timeline
- 2026–2027: Planning window. DOR expected to issue proposed rules in 2027. Litigation continues.
- January 1, 2028: Tax attaches. Washington residents with household AGI above $1M begin incurring liability on the excess.
- April 2029: First tax returns due; first payments; first wave of audits.
- 2029+: Enforcement pattern established. Expect residency audits to become a routine feature of Washington high-income tax life.
Key takeaways
- ESSB 6346 imposes a 9.9% tax on federal AGI above $1 million per household, effective January 1, 2028.
- The base is federal AGI, so QSBS §1202 exclusions flow through; non-QSBS gain does not.
- The law creates a meaningful marriage penalty and stacks with Washington's 7% capital gains tax.
- The 20-month runway before the effective date is the most valuable planning period.
- Litigation is pending but should not be the plan.
- The four planning levers — accelerate, relocate, restructure, requalify — are best used in combination.
How we can help
If you are a founder, executive, or investor with a Washington nexus and a meaningful income or liquidity event on the horizon, the planning window is open and closing. Book a consultation to walk through your specific situation.
Last reviewed: April 16, 2026. ESSB 6346 regulations are pending; this guide will be updated as the Department of Revenue issues implementing rules. Nothing in this article is legal or tax advice and reading it does not create an attorney-client relationship.
