ESSB 6346 imposes a 9.9% tax on household income above $1 million. Not individual income. Not individual-filer income. Household. For married filers, that single structural choice builds a meaningful marriage penalty into the Washington income tax that will affect tens of thousands of high-earning Washington couples starting in 2028.
This post explains how the marriage penalty works, why it exists in this form, and what planning options exist for couples who will be hit by it.
The math, in one example
Consider two Washington high-earning professionals. Each earns $700,000 of W-2 income per year. Under ESSB 6346:
- If they are unmarried and each files individually: Neither clears the $1M threshold on their own. Combined state income tax: $0.
- If they are married and file jointly: Household AGI of $1.4M. Taxable amount: $400K (the excess over $1M). State income tax: $39,600.
- If they are married and file separately: Washington has not finalized how married-filing-separate will be treated, but under every other state's similar regime, MFS filers continue to share the household threshold proportionally. Combined state tax: approximately $39,600, split between the two returns.
The penalty on this representative couple: $39,600 per year, every year, for as long as both spouses are Washington residents earning at this level. Over a 15-year career, that is nearly $600,000 of additional state tax attributable solely to being married.
Why ESSB 6346 was structured this way
The drafting history of ESSB 6346 shows the legislature explicitly chose a household threshold rather than per-filer. Two reasons were offered publicly:
- Revenue. A per-filer $1M threshold would have exempted a meaningful number of high-earning dual-income couples. Revenue projections would have dropped.
- Simplicity. A household threshold mirrors federal AGI reporting conventions for joint filers, avoiding the need for a separate Washington filing status regime.
The marriage penalty was, in other words, a feature of the tax design, not an oversight. It is consistent with several other state high-income taxes (including Oregon's top bracket and California's upper brackets) that either flatten the brackets for joint filers or impose outright marriage penalties in the top ranges.
How big does the penalty get?
The penalty scales with how close the combined household is to $1M and how concentrated the income is between spouses. A few representative cases:
- $600K + $600K = $1.2M household: Taxable excess $200K. Tax: $19,800. Unmarried combined tax: $0. Marriage penalty: $19,800/year.
- $700K + $700K = $1.4M household: Taxable excess $400K. Tax: $39,600. Unmarried combined tax: $0. Marriage penalty: $39,600/year.
- $900K + $900K = $1.8M household: Taxable excess $800K. Tax: $79,200. Unmarried combined tax: $0. Marriage penalty: $79,200/year.
- $1.5M + $0 (single-earner household): Taxable excess $500K. Tax: $49,500. Unmarried combined tax: $49,500 (the earner would hit $500K over the $1M solo threshold). Marriage penalty: $0.
The penalty is largest when both spouses earn roughly equally at levels just below $1M each. It is zero or near-zero when one spouse earns all the income, or when one spouse earns significantly less.
The year-to-year volatility problem
For households whose income is roughly stable from year to year, the penalty is predictable and chronic. But a larger set of Washington households — founders, investors, equity-compensated executives — have a different problem: episodic high-income years.
A founder couple with modest cash comp plus a large RSU vest in 2028 might see household AGI spike to $5M in a single year before returning to $600K the next. In that spike year, the household hits the threshold hard regardless of marital status. The question is whether the $1M threshold applies per-spouse or per-household when the non-earning spouse contributes very little.
Under the household structure, it is per-household. The couple loses the "first $1M" that two unmarried earners would have had. For concentrated liquidity events, the marriage penalty on a one-year spike can easily exceed $100,000.
Planning responses
No planning option eliminates the marriage penalty for a couple that remains married. But several can materially reduce exposure:
1. Time major recognitions around the marriage
For engaged couples with a major liquidity event on the horizon, the sequencing of the wedding and the transaction matters. Closing a large sale before the wedding means the seller's income passes the individual $1M threshold. Closing after the wedding combines the household.
This is awkward to put in writing. It is nonetheless real. For couples with an anticipated 2028+ transaction of meaningful size, the tax savings of closing pre-marriage can reach six figures.
2. Balance income distribution between spouses
If both spouses have independent income sources, the total tax does not change based on who earns what (the household pools). But for spouses with flexibility — partners in a family business, spouses of founders with equity, couples with family investment partnerships — allocating income toward the lower earner can pull a household back below the $1M threshold in marginal cases.
3. Maximize retirement deferral
401(k), 403(b), and defined benefit plan contributions reduce federal AGI. Washington's income tax is on federal AGI. Every dollar of deferred compensation is a dollar out of the Washington tax base. For households just over the $1M threshold, aggressive retirement-plan funding can push them back under.
4. Front-load charitable giving
Charitable contributions do not reduce federal AGI (they reduce taxable income via itemized deduction). But donor-advised fund bunching combined with appreciated-asset giving can reduce the realized gain that would otherwise flow into AGI.
5. Use non-grantor trusts for a portion of family investment income
For couples whose investment income alone pushes them over the household threshold, a non-grantor trust sitused outside Washington can shift that investment income out of the spouses' combined AGI. See Trust Planning for Washington High Earners.
6. Change domicile
The cleanest solution, as with every aspect of ESSB 6346: leave Washington. A dual-earner household that moves to Texas before the 2028 tax year saves the full $39,600+ per year, every year. For couples in the prime earning decade of their careers, that is a meaningful number. See How to Leave Washington.
Will the legislature fix this?
Marriage penalty design features in state income taxes tend to be durable. The federal government eliminated its marriage penalty on most brackets in 2018, but did so by doubling the brackets entirely — which was revenue-negative and politically expensive. Washington's ESSB 6346 was drafted with household-aggregated thresholds specifically to maximize revenue. Legislative reversal would cost the state several hundred million dollars per year and would have to find alternative revenue.
Plan on the marriage penalty being a permanent feature of the law unless and until political economy changes.
Takeaways
- ESSB 6346 creates a real marriage penalty because the $1M threshold is per-household, not per-spouse.
- The penalty is largest for dual-earner couples with roughly equal incomes in the $600K–$1M each range.
- A single-earner household at the same total income pays the same tax either way; marriage is not penalizing.
- Planning options exist — retirement deferral, non-grantor trusts, domicile change — but most cap the damage rather than eliminate it.
- Domicile change is the one option that fully eliminates the penalty for couples willing and able to move.
For the full picture of ESSB 6346, see the Complete Guide. For relocation: How to Leave Washington.
Last reviewed: April 16, 2026. Nothing in this article is legal or tax advice. ESSB 6346 regulations are pending and the treatment of married-filing-separately returns has not yet been finalized.
