Updated September 10, 2026
A founder’s Washington tax exposure depends on what is sold, how payment is structured, where the founder is taxable, and how much gain qualifies for the Section 1202 exclusion. Those questions should be resolved while there is still time to change the transaction or prepare the supporting records.
Start with the main income-tax guide
As enacted, ESSB 6346 imposes a 9.9% personal income tax beginning January 1, 2028. The calculation starts with federal adjusted gross income, applies Washington modifications and deductions, then credits. The initial standard deduction is $1 million, shared by spouses and registered domestic partners.
The main Washington income-tax guide covers the general rules. This article focuses on the decisions founders and investors need to make. The Washington Founder Exit Map provides a framework for sequencing them.
Identify what the transaction pays you for
Start with a schedule separating stock-sale proceeds, compensation, business income and deferred payments. A headline acquisition price does not tell you which tax rules apply to your share of the proceeds.
- Stock-sale gain: establish the shares sold, proceeds, basis, holding period and available QSBS exclusion.
- Compensation: identify option exercises, RSU settlements, bonuses, retention payments and consulting arrangements separately from stock consideration.
- Pass-through income: review income allocated by a partnership or S corporation, including income the business retains.
- Deferred consideration: determine when and how an earnout, installment payment or escrow amount is recognized. The closing date alone does not answer that question.
A company’s asset sale requires a separate corporate- and shareholder-level analysis. Do not assume the result matches a founder’s direct sale of qualifying stock.
Establish the excluded and non-excluded gain
Gain validly excluded under Section 1202 stays outside Washington’s new income-tax base under the enacted law. The remaining gain requires a separate calculation. Holding qualifying shares does not mean every dollar received in an exit is excluded.
Use the main QSBS guide to check eligibility, acquisition dates, holding periods, the per-issuer limitation and supporting records. The focused article on QSBS and Washington’s two taxes explains the state treatment and includes a partial-exclusion example.
For angel investors, do the eligibility work when investing and preserve the records through the holding period. A later secondary sale does not, by itself, establish that the seller’s shares are ineligible: examine how that seller acquired the stock and the other Section 1202 requirements.
Calculate the capital gains credit before adding tax burdens
Washington’s capital gains excise tax and new income tax are coordinated. Section 302 removes federal long-term gains and reverses included long-term losses, then reconstructs the specified Washington gain amount for taxpayers owing capital gains tax. Section 205 provides a nonrefundable income-tax credit for the same year’s capital gains tax, limited to income tax otherwise due. See ESSB 6346, sections 205 and 302.
A simple illustration shows why the credit matters. Assume capital gains tax is $100,000 and income tax before that credit is $140,000, with no other credits. The credit leaves $40,000 of income tax. Combined Washington tax is $140,000, not $240,000. These are assumed liabilities, not a calculation for a particular size of exit.
To measure the tax cost of an additional payment, recalculate both liabilities and the credit with and without that payment. A combined headline rate cannot replace that comparison. Use the capital gains tax guide for that tax’s rates, deductions and allocation rules.
Review equity compensation and employer costs separately
For each award, assemble the grant documents, vesting schedule, exercise or settlement terms, and relevant work-location history. Then compare the tax consequences of the available choices with their cash cost and investment risk.
The option-exercise timing guide and Washington stock-options and RSUs article cover the award-specific analysis. An earlier exercise can require cash and create tax before there is liquidity.
For a Seattle employer, model JumpStart and the Social Housing Tax as employer costs. They are employer liabilities, not amounts to add to an employee’s personal marginal tax rate. Apply each tax’s own eligibility and sourcing rules.
Plan for allocated income and the cash to pay the tax
Partners and S corporation shareholders can recognize allocated income without receiving matching cash distributions. Review the business’s tax-distribution provisions and projected cash needs alongside the owner’s return. Federal allocation rules appear in Section 702 and Section 1366.
Compare the available Washington pass-through entity election, owner-level treatment and applicable credits using the S corporation, LLC and partnership guide. Evaluate participating owners separately; an election’s benefit should be calculated before committing to it.
Include the household in the model
A founder’s exit or compensation can coincide with a spouse’s earnings. Model the combined income and shared deductions. The marriage-penalty analysis provides the household examples, and the income-tax calculator provides an initial illustration.
Evaluate residency before choosing transaction timing
A relocation plan needs evidence of the actual move and an analysis of any Washington-source income that remains. Review the proposed closing and payment dates with residency counsel before making commitments.
Use the leaving Washington guide for domicile planning and the 30-day rule explanation for the residency exception. Cross-border employment requires a separate review of Washington work and income sourcing.
Related issue: professional athletes and NIL income
Athletes and their advisers need an income and residency analysis tailored to their contracts. For qualifying nonresident professional-team members, section 404 uses Washington duty days relative to total duty days, subject to permitted alternatives. Nonresident student-athlete NIL income has separate sourcing rules under section 407. Read the athlete provisions (duty-day §404 walkthrough; session-law text).
Do not apply the full standard deduction automatically to a nonresident or part-year resident: section 315 requires proration. Nor does a student’s out-of-state home address settle domicile or statutory residency. Assemble duty-day records, contracts, work locations and residency facts before estimating the bill.
Keep legal developments in the dedicated trackers
Use the I-645 tracker for initiative developments and the constitutional analysis for the legal arguments. Check the operative law and any court orders before implementing a plan. A forecast about repeal or litigation is not a substitute for that check.
Prepare one transaction model
Give your advisers a common set of assumptions: ownership and basis records, QSBS support, compensation terms, expected payments, other household income, business allocations, residency facts and projected deductions and credits.
Compare plausible scenarios using those same assumptions. Identify what must happen before an exercise, signing, closing or move, and who is responsible for each step. Update the model when the deal terms or facts change.
My view
The shared household deduction and the interaction of business, compensation and investment income make this tax consequential for founders. I opposed the law. For planning purposes, my recommendation is concrete: document eligibility, model the actual transaction, and make decisions while the terms are still open.
For help with QSBS, equity compensation or a Washington transaction, schedule a consultation.
This article provides general information, not legal or tax advice for a particular transaction, and does not create an attorney-client relationship.
