A founder selling $10 million of stock gain fully eligible for the federal QSBS exclusion could save roughly $1.3 million in California tax by becoming a Washington resident before the sale.
That is a substantial reason to consider a move. But the result depends on what you are selling, when you sell it, and whether you actually ended your California residency.
Start with three buckets:
- What follows you: compensation attributable to work you performed in California, including some option and RSU income.
- What generally stops: California tax on ordinary investment stock gains realized after you become a genuine nonresident.
- What starts in Washington: exposure to Washington’s capital gains tax, estate tax, and the income tax scheduled to begin in 2028.
The planning exercise is to identify which dollars belong in each bucket before you commit to a transaction.
Where the biggest savings come from
California does not recognize the federal exclusion for qualified small business stock under Section 1202. A California resident can qualify for a full federal exclusion and still owe California tax on the gain. California FTB guidance.
Washington’s capital gains tax takes a different approach. Gain excluded from federal net long-term capital gain under Section 1202 is also outside Washington’s capital gains tax. The Department of Revenue confirms that treatment expressly. Washington DOR’s QSBS guidance.
For a $10 million gain fully eligible for exclusion, applying California’s 13.3% top marginal rate produces a $1.33 million illustration. The actual California calculation uses graduated rates and depends on the taxpayer’s other income, deductions, and filing status. Think roughly $1.3 million, not a guaranteed $1.33 million bill.
The federal exclusion is available in either state. The move changes the state tax result.
What if the stock is not QSBS?
A move can still save tax, but Washington may collect capital gains tax on the sale. Here is a $2 million long-term stock-gain illustration using published 2025 tax parameters. It is not a quote of the unpublished 2026 deduction.
| State result | Illustrative tax on the $2 million gain |
|---|---|
| California: all additional gain taxed at 13.3% | $266,000 |
| Washington: $2 million less $278,000 deduction; 7% on the first $1 million, 9.9% on the remaining $722,000 | $141,478 |
| Difference | $124,522 |
Assumptions: the founder’s other California taxable income already exceeds the top-rate threshold; the Washington standard deduction is fully available; no QSBS exclusion, other exemption, deduction, credit, or loss applies; and the move ends California residency before the sale. This compares state tax on the additional gain, excluding federal tax. For an actual 2026 or 2027 sale, substitute that year’s deduction. For 2028 and later, also calculate the new income tax and its capital-gains credit.
Your founder shares and your options are different problems
“Startup equity” is not a single tax category.
For nonqualified options, California generally allocates compensation using California workdays from grant to exercise (or the end of employment, if earlier). For RSUs, the relevant service period is generally grant to vest. The details depend on the award. FTB Publication 1004.
For example, assume a founder genuinely moves from San Francisco to Seattle in 2027, then sells founder shares for a $10 million gain fully eligible for the federal QSBS exclusion. Assuming the shares are ordinary investments with no California business situs, California generally would not tax that post-move gain, and the excluded gain would also escape Washington’s capital gains tax.
The same founder exercises nonqualified employee options after the move, recognizing $500,000 of compensation. If 800 of the 1,000 workdays from grant to exercise were California workdays, the workday method allocates 80%, or $400,000 of compensation, to California. That is taxable income allocated to California, not a $400,000 tax bill. The move changes the stock-gain result while leaving much of the option income taxable in California.
When California generally stops taxing stock gains
California generally treats a nonresident’s investment stock gain as income sourced to the person’s state of residence, subject to exceptions such as a California business situs. A company’s California headquarters, by itself, does not make all of its shareholders’ stock gains California-source. R&TC § 17952.
The distinction is especially important when comparing a shareholder’s stock sale with a transaction producing income through an operating business. The deal’s tax structure matters.
Installment payments also need separate attention. In the FTB’s example, a California resident sells stock on installments and then moves away. California continues taxing the gain in later payments because the seller was a California resident when the stock was sold. Moving before collection does not produce the same result as moving before the sale. FTB Publication 1100.
There is no magic waiting period
The useful question is: Will the facts establish that you had ended your California residency before the sale?
California’s residency analysis considers both domicile and whether your presence or absence is temporary or transitory. Changing a mailing address or obtaining a Washington driver’s license is evidence, but neither settles the issue. FTB residency guidance.
As a planning matter, completing the move before a letter of intent gives you more room to establish and document the facts. An LOI is not a statutory residency deadline, however, and a tax motive does not answer whether you actually moved.
If a transaction is already underway, have counsel examine the transaction timeline alongside the residency timeline. Signing, closing, and payment can occur on different dates. Have counsel determine when the sale is completed for tax purposes under the agreement and closing conditions, then compare that date with the residency change. Receiving the cash after your move is not enough if the sale occurred while you were still a California resident.
Pre-sale gifts and trust transfers raise additional questions. Those belong in the same planning conversation, even though transferring stock and changing your residence are distinct actions.
Build the residency file while you move
The strongest file records what happened as it happened:
- When you began occupying your Washington home.
- What happened to your California home.
- Where your spouse and children live.
- Your work locations and travel days.
- Changes to licenses, registrations, insurance, and professional relationships.
- Records showing where you conduct daily life.
Keeping a California house does not automatically settle residency. But retaining a home available for your use—especially one where your family continues living—is a fact that requires careful attention.
The FTB’s own audit manual examines homes, work, physical presence, financial records, and everyday expenses. Your documentation should tell a consistent story across those categories. FTB Residency and Sourcing Technical Manual.
What Washington will charge
Washington can offer substantial savings, but you still need to calculate the destination’s taxes.
| Tax | What matters for a founder |
|---|---|
| Capital gains tax | The first $1 million of taxable Washington capital gains, after applicable deductions, is taxed at 7%. The portion above that is taxed at 9.9%. Fully excluded QSBS gain is outside this tax. |
| Income tax beginning in 2028 | The enacted law imposes a 9.9% tax on Washington taxable income, with a $1 million standard deduction. Spouses and registered domestic partners share that deduction. |
| Estate tax | For deaths on or after July 1, 2026, the exclusion is $3 million and rates range from 10% to 20%. This deserves attention alongside the exit calculation. |
Sources: capital gains rates, 2028 income-tax law, estate-tax exclusion, and estate-tax rates.
The two Washington tax rates do not simply stack. Beginning in 2028, the income-tax law provides a nonrefundable credit for Washington capital gains tax imposed for the same year. It also makes specific adjustments to long-term capital gains when calculating the income-tax base. A projection should calculate both taxes and the credit rather than add the headline rates.
Fully excluded Section 1202 gain remains outside the income-tax base under the enacted framework. For taxable gains, wages, and other income, the 2028 rules make an individualized calculation more important. ESSB 6346, Sections 205 and 301–302.
The sequence I would work through
Before choosing dates: model the transaction. Separate stock gain from compensation. Compare the California and Washington results for the expected sale year. Include estate planning in the discussion.
Before relying on QSBS: verify it. Review the issuance documents, acquisition date, applicable holding period and exclusion limit, corporate status, gross assets, and business activities. A cap-table label is not enough.
As you move: document the facts. Keep a dated record of your homes, family location, work arrangements, and travel. Resolve inconsistencies while the evidence is easy to obtain.
Through vesting or exercise: maintain workday records. The move is a milestone in the sourcing calculation, not necessarily the end of it. Continue tracking the relevant service period, including later California workdays.
Before signing: review the deal structure and timing. Confirm that the tax treatment assumed in the model matches the transaction you are actually doing.
Afterward: file consistently and preserve the record. Address part-year and nonresident filing obligations as applicable. Keep the residency, equity, and transaction records supporting your returns.
Considering a move before an exit? Book a 20-minute planning call to review your residency timeline, equity compensation, and QSBS eligibility.
Related reading
- Washington vs. California: A Tax Comparison for Founders and Investors
- Washington vs. California: Residency Safe Harbors Compared
- The Washington Domicile Change Checklist
- QSBS and Washington Residency: Timing Section 1202, Your Sale, and Your Move
- Does QSBS Avoid Washington’s Income and Capital Gains Taxes?
This is general information, not legal or tax advice. The result depends on your residency facts, equity, transaction structure, and the law applicable in the year of sale.
