California to Washington: The Sourcing Fight Behind a No-Tax Move

California runs nine brackets from 1 percent to 12.3 percent and adds a 1 percent Mental Health Services Tax on taxable income above 1,000,000 dollars, for a top marginal rate of 13.3 percent. Since the wage cap on State Disability Insurance withholding came off in 2024, high earners also pay an uncapped payroll tax on top of that, which the Tax Foundation puts at a combined 14.6 percent top rate on wage income. Washington has never taxed wages. For most of the last century that sentence was the entire analysis of this corridor, and for a software engineer moving from Mountain View to Bellevue it was close enough to true.

It is not true anymore, and the change did not happen quietly. Washington has imposed an excise tax on long-term capital gains since 2022. In March 2026 the legislature passed and Governor Ferguson signed Engrossed Substitute Senate Bill 6346, a 9.9 percent tax on Washington taxable income above 1,000,000 dollars per household, effective January 1, 2028, with first returns and final payments due in 2029. It applies to residents, to part-year residents, and to nonresidents with Washington-source income. A tax that looks a great deal like an income tax is now on the books in the state people move to in order to stop paying one.

That reframes the whole corridor. The question stops being whether Washington taxes you and becomes a much more specific pair of questions: what California still taxes after you leave, and what Washington has started taxing now that you have arrived. Both of those are sourcing questions, not residency questions, and people moving from California to Washington consistently answer the residency question well and the sourcing questions not at all.

Our California residency guide rates the state 5 out of 5 on exit stickiness and 5 out of 5 on audit aggressiveness, the worst pair of scores on our map. Our Washington residency guide rates Washington 3 and 3, which is not the 1 and 1 that a no-income-tax state used to earn and is a direct consequence of the two taxes above. This article is informational and is not legal or tax advice; work through your own facts with a qualified CPA or tax attorney.

Anyone planning this corridor in 2026 needs the timeline rather than the headline, because three separate things are happening to the Millionaires’ Tax at once and they resolve on different dates.

The statute itself is settled in its terms. The rate is 9.9 percent, the threshold is 1,000,000 dollars of Washington taxable income per household, and spouses and domestic partners share a single 1,000,000 dollar standard deduction rather than getting one each. The threshold is indexed for inflation biennially starting in 2029. Washington taxable income starts from federal adjusted gross income with modifications, including an add-back of capital gains taxes, income from incomplete non-grantor trusts, and an owner’s distributive share of pass-through entity tax expense. Nonresidents are taxed only on Washington-source income, and part-year residents allocate between the resident and nonresident portions of the year. There are non-refundable credits for the capital gains tax, for business and utility taxes, for income tax paid to another state, and for pass-through entity tax payments, and none of them carry forward.

The constitutional question is open. In April 2026 plaintiffs including a pair of construction business owners, a Klickitat County farmer and a Kent trucking company owner filed suit in Klickitat County Superior Court, represented by former Washington Attorney General Rob McKenna and former state Supreme Court Justice Phil Talmadge. Their argument runs through the 1933 decision in Culliton v. Chase, which held that income is property and that the Washington constitution therefore permits taxing it only at a flat rate capped at 1 percent. That is the same constitutional wall the capital gains excise tax had to get around, and the state got around it by calling that tax an excise rather than a tax on income.

The political question has a date on it. The Washington Supreme Court unanimously denied a petition from Brian Heywood and Let’s Go Washington seeking to force a referendum on ESSB 6346, holding the measure exempt from voter challenge under the state constitution. An initiative to repeal the tax is on the November 2026 ballot instead.

So the honest statement about this corridor right now is that Washington has enacted a 9.9 percent tax on high incomes, that it does not begin collecting until 2029 for tax year 2028, that a court may strike it down on a ninety-three-year-old precedent, and that voters may repeal it in November. None of those four facts cancels the others. What they jointly rule out is planning a nine-figure relocation on the assumption that Washington is a zero-income-tax state in 2028, because that is currently an open question rather than a feature of the map.

The tax that actually governs most moves on this corridor today is older and less discussed. RCW 82.87 imposes an excise tax on the sale or exchange of long-term capital assets, and it has been collecting since 2022.

The Washington Supreme Court upheld it in Quinn v. State, No. 100769-8, decided in 2023. The court held 7 to 2 that the tax is a constitutionally valid excise tax on the privilege of selling or exchanging capital assets rather than an unconstitutional tax on property or income, reversing the trial court and clearing the way for the tax to take effect. That holding is the load-bearing beam under the entire structure, and it is the reason the Millionaires’ Tax litigation matters to this corridor even for people who will never earn a million dollars in a year: the state’s whole approach to taxing capital depends on a distinction between an excise on a transaction and a tax on income.

The rates are tiered. Engrossed Substitute Senate Bill 5813, Chapter 421, Laws of 2025, layered an additional 2.9 points on top of the original 7 percent, so the tax now runs 7 percent on the first 1,000,000 dollars of taxable gain and 9.9 percent above that, starting with tax year 2025 and returns due April 15, 2026. The tiers apply after an annual standard deduction, which was 270,000 dollars for 2024 and 278,000 dollars for 2025 per individual, married couple or domestic partnership, adjusted annually for inflation. Returns are due the same day the federal return is due.

The exemptions matter as much as the rates, and they are specific rather than general. Real estate is exempt outright, as are interests in privately held entities to the extent the gain is attributable to real estate. Retirement account assets are exempt. So are condemned assets, certain livestock, depreciable business assets, timber and timberlands, commercial fishing privileges, and goodwill from the sale of a franchised auto dealership. Read that list next to a typical California exit and the pattern is obvious: the person who sells a house on the way out is fine, and the person who sells a founder’s stake or a concentrated equity position is not.

Then there is the allocation rule, which is the single most important sentence in this corridor. For intangible property such as stock, Washington allocates the gain to Washington if the taxpayer was domiciled in Washington at the time of the sale or exchange. Not where the company is. Not where the shares were earned. Where you were domiciled on the day the transaction happened.

Put the two states’ rules side by side and the standard plan for this corridor stops working.

The plan is familiar: hold the appreciated stock, move to Washington, sell after the move, pay nothing. It is the same plan people run into Texas, Nevada and Florida, and on those corridors the destination half of it is sound. On this one it is not, because Washington’s capital gains excise tax follows domicile at the moment of sale. Selling after you have successfully become a Washington domiciliary is precisely the fact pattern that makes the gain Washington-taxable. A 5,000,000 dollar gain realized as a new Washington domiciliary, against a 278,000 dollar deduction and the tiered rates, is a Washington liability in the high six figures.

Selling before the move does not solve it either, because then you are a California resident on the date of sale and California taxes capital gains as ordinary income at the same rates as wages, with no preferential long-term rate. A 50,000 dollar long-term gain is taxed identically to 50,000 dollars of salary, and so is a 5,000,000 dollar one.

What about the period in between? This is where our California residency guide is blunt about the risk. The Franchise Tax Board concentrates residency audits on high earners whose departure date lines up with a liquidity event, and a claimed move date of late December followed by a January capital gain is the classic trigger. The gap between the two taxes is not a planning window. It is the exact shape of the fact pattern California audits.

Washington does provide a credit, and it is narrower than it sounds. RCW 82.87.100(2) allows a credit against the capital gains excise tax equal to the legally imposed income or excise tax paid in another taxing jurisdiction on capital gains derived from capital assets within that other jurisdiction. Three conditions have to be met: the other jurisdiction imposed an income or excise tax on gain included in Washington capital gains, the taxpayer actually paid it before filing the Washington return, and the gain arose from the sale or exchange of a capital asset within that other jurisdiction. The credit cannot exceed total Washington liability and does not carry back or forward. Where another state taxes capital gains alongside other income, the Department of Revenue’s interim guidance prorates, multiplying the tax paid by the ratio of the gain taxed in both states to total gross income in the other state. Its own worked example is a taxpayer with 10,000 dollars of long-term gain taxable in another state who paid 8,127.15 dollars of total state tax there and received a credit of 812.72 dollars.

Notice the third condition. The credit is keyed to a capital asset located within the other jurisdiction, and shares of stock are not located anywhere in that sense. That is why this credit does real work for someone who sold tangible property or a business with a physical footprint in California, and much less for the person whose whole exposure is a concentrated position in a single ticker. Run both states’ numbers on the same gain, in both sequences, before picking a date. A residency savings and exposure calculator is the right place to start, because on this corridor the answer is not a rate comparison, it is a two-state arithmetic problem with a date as the variable.

The other half of the sourcing fight runs backwards, and it does not care where you live at all.

Compensatory equity is the main event. Under 18 CCR 17951-5, compensation for personal services is apportioned to California in the manner that reasonably attributes to the state the portion of total compensation earned by services performed there, and the regulation states that one reasonable method is an allocation based on time worked. FTB Publication 1004, the Equity-Based Compensation Guidelines, applies that to equity: for a nonstatutory stock option granted while you were a California resident and exercised after you left, the California-source share is the ratio of California workdays to total workdays between grant and exercise, applied to the exercise spread. For restricted stock units the measurement period closes at vesting rather than exercise. Vacation days, holidays and weekends come out of the denominator.

Work an example that is ordinary on this corridor. Options granted in 2020, vesting through 2023 while you worked in San Francisco, you move to Washington, you exercise in 2027 with a 750,000 dollar spread. If roughly half the workdays between grant and exercise were California workdays, roughly 375,000 dollars of that spread is California-source income and California taxes it at resident rates whether you live in Bellevue, Bellingham or Barcelona. Your Washington address changed the state that taxes your next dollar. It did nothing to the state that earned your last four years.

The same logic reaches further than equity. Nonqualified deferred compensation earned in California generally keeps its California-source character on distribution, subject to the federal limits in 4 U.S.C. section 114 that reserve taxation to the state of residence at the time of receipt for genuine retirement-plan-style periodic payments. Income from a California business or from California real property continues to be taxed to nonresidents indefinitely, with no expiry and no relationship to your day count.

The case that teaches this best is the one California practitioners cite for something else entirely. In Appeals of Stephen D. Bragg, 2003-SBE-002, decided May 28, 2003, Bragg moved to a cattle ranch in Arizona on approximately April 1, 1993. The State Board of Equalization held he won the residency question, concluding he was a resident of Arizona in 1993 and that he, although a California resident at one time, left the state in 1993 for other than a temporary or transitory purpose, rejecting his own 1997 amended return claiming California residency for the whole year. He lost on sourcing instead. A covenant not to compete executed on the 1988 sale of his interest in Bragg Investment Company paid 1,333,333 dollars a year, his community property half being 666,666.50 dollars, and the Board held that income California-source and apportioned 84.05 percent of it to California under the three-factor formula adopted in Appeals of Milhous, sustaining assessments of 48,153 dollars for 1993 and 42,658 dollars for 1995 plus a 10,664 dollar late filing penalty. The same decision is the origin of the nineteen-factor closest-connections list California practitioners still call the Bragg factors.

Winning the residency fight and losing the case is the normal outcome when the income has California history in it. That is what people miss when they treat a move as the end of California exposure rather than the beginning of a narrower and longer-running argument about where specific dollars were earned.

Because Washington has no general income tax return, movers assume it has no residency rules to get wrong. It has both a statutory test and a domicile test, and they are written in the capital gains statute where nobody thinks to look.

RCW 82.87.020 defines a resident two ways. The first is domicile: an individual domiciled in Washington during the taxable year, subject to a narrow exception. The second is a statutory prong that should be familiar to anyone who has read New York’s or Massachusetts’s: an individual who is not domiciled in Washington but who maintained a place of abode and was physically present in the state for more than 183 days during the taxable year. For that count, the statute defines a day as a calendar day or any portion of a calendar day. Washington counts a partial day as a whole day, exactly the way California does when it applies its own presumption.

The exception to the domicile prong is the corridor’s most dangerous piece of fine print, because it reads like a safe harbor and behaves like a tripwire. A person domiciled in Washington is treated as a nonresident only if all three conditions hold for the entire taxable year: they maintained no permanent place of abode in Washington during the entire year, they maintained a permanent place of abode outside Washington during the entire year, and they spent in the aggregate not more than 30 days of the year in Washington. Thirty days, not 183. And failing any one of the three conditions voids the whole thing, so keeping a Washington place of abode for a single month defeats it no matter how few days you spent there.

The domicile test itself is common law and the Department of Revenue has published interim guidance on it, precisely because high earners have tried to time a departure around a large sale. Domicile is a residence in fact coupled with the intent to make that place of residence one’s home, and an individual may hold only one domicile at a time. Once established in Washington, domicile is presumed to continue, and the taxpayer bears the burden of proving it changed to somewhere outside the state. Establishing a new domicile requires physical presence at the new place together with the intent to make it a permanent home. The Department’s nonexclusive factor list covers length of time in a location, expressed intent, place of business or employment, bank account locations, the address on the tax return, where personal and real property sits, motor vehicle registration, driver’s license, where the children go to school, voter registration, professional licenses, in-state tuition claims, hunting and fishing license claims, and mailing address, with no single factor dispositive. The guidance rests on a line of Washington cases including In re Estate of Lassin, 33 Wn.2d 163 (1949), Ex parte Mullins, 26 Wn.2d 419 (1946), Sasse v. Sasse, 41 Wn.2d 363 (1952), Stevens v. Stevens, 4 Wn. App. 79 (1971), and In re Marriage of Strohmaier, 34 Wn. App. 14 (1983).

And the guidance says one thing outright that matters to anyone arriving from California with a house to sell: selling your former home or acquiring a new one is not conclusive in establishing domicile. That sentence cuts both ways on this corridor. It is the answer to a Californian who thinks a Bellevue closing settles the question, and it is the answer to a Washingtonian who thinks listing the Kirkland house the week before a stock sale settles it either.

California is the harder side of this corridor and it is harder in a specific way: there is nothing to count and, for one category of taxpayer, nothing to wait out.

Under Revenue and Taxation Code section 17014 and FTB Publication 1031, a resident is anyone present in California for other than a temporary or transitory purpose, plus anyone domiciled in California who is outside the state for a temporary or transitory purpose. There is no bright-line day count as the primary test. It is a facts-and-circumstances closest-connections analysis, which means there is no number that makes you safe. Section 17016 adds a presumption running the other way: presence in California for more than nine months of the tax year, roughly 274 days, presumes residency, rebuttable with evidence the presence was temporary or transitory. There is no symmetrical safe presumption for spending less than nine months. FTB can find residency based on closest connections at a low day count.

The one statutory safe harbor is narrow and does not fit most moves on this corridor. Under section 17014(d), a person domiciled in California who is absent for an uninterrupted period of at least 546 consecutive days under an employment-related contract is treated as a nonresident for that period, provided they maintain no permanent place of abode in California and spend no more than 45 days in California in any taxable year covered by the contract. It does not apply to self-employed people contracting with their own entity, and it fails entirely if the abode condition is violated. A Seattle job offer is not an overseas contract, and the safe harbor is not the mechanism most movers on this corridor are using.

FTB’s nine-factor domicile analysis weighs where your spouse and children live, where your principal residence is, where your driver’s license and vehicles are registered, where you are registered to vote, the location of your banks and professional relationships including doctor, dentist, accountant and attorney, the state on your last income tax return, and your permanent employment location. No single factor controls, but family location and principal home carry the most practical weight. The enforcement inventory behind it is the most aggressive in the country and includes cell phone geolocation and credit card transaction data, 1099s and K-1s issued to a California address after the claimed move date, DMV and voter file cross-checks, declared-homestead filings in the new state cross-referenced against California property still owned, social media check-ins, utility and internet account activity at the California residence, informant tips, and private investigators in high-dollar disputes.

Then the limitations period, which is the fact that should govern how you file. For a filed part-year or nonresident return, FTB has four years to assess. If no California return was ever filed for a year FTB believes you were a resident, there is no statute of limitations at all under R&TC section 19057(a). That asymmetry is why the silent nonfiler, not the honest part-year filer, is FTB’s highest-risk target, and why filing Form 540NR for the year of the move is almost always the right call even when you are confident the move was clean. Filing starts a clock. Not filing means there is no clock.

Practitioners report that FTB residency audits typically open with the year of the claimed move and pull in the following one to two years, extending further when a major liquidity event anchors the dispute. Informal estimates for defending a contested California residency case through the administrative process run roughly 15,000 to 75,000 dollars or more, climbing sharply if it reaches the Office of Tax Appeals.

The most surprising thing about this corridor is what happens when you stop comparing income tax rates and compare tax systems.

On the 2026 State Tax Competitiveness Index, California ranks 48th overall. Washington ranks 45th. Three places. The state with no wage income tax and the state with the highest top marginal rate in the country sit within a rounding error of each other at the bottom of the same table, and the reason is that Washington raises its money somewhere else. State and local tax collections run 7,745 dollars per capita in Washington against 8,942 dollars in California, a real gap but not the chasm the headline rates imply. Washington funds itself with a 6.50 percent state sales tax that averages 9.51 percent combined with local rates, against California’s 7.25 percent state rate averaging 8.99 percent combined. On sales tax, the no-income-tax state is the more expensive one. Washington also levies a Business and Occupation gross receipts tax instead of a conventional corporate income tax, which reaches revenue rather than profit and which anyone moving a consulting practice or a small company across the border needs to price separately from their own return.

Property tax is close to a wash and runs slightly against the move: an effective 0.75 percent of owner-occupied housing value in Washington against 0.70 percent in California. That California number carries a caveat worth naming, because it is an average across a state where Proposition 13 caps the base rate at 1 percent of assessed value with a 2 percent annual increase cap. Long-tenured California owners pay far less than a recent buyer on an identical house, and Proposition 19 lets homeowners 55 and older, disabled owners and wildfire or disaster victims transfer that low assessed value to a new California home up to three times. That transferable basis is a California-only benefit, and leaving gives it up permanently. For someone who bought in 1998 and is weighing a Washington purchase at current Puget Sound prices, the property tax line can move the wrong way by a wide margin.

The estate tax is the reversal that catches retirees. California repealed its estate tax in 1982 and has no inheritance tax. Washington has one of the heavier estate taxes in the country. The applicable exclusion is 3,076,000 dollars for deaths from January 1 through June 30, 2026 and 3,000,000 dollars for deaths on or after July 1, 2026, and the Department of Revenue states the amounts are not set to increase going forward because the CPI adjustment in the statute has expired. Engrossed Senate Bill 6347, signed March 24, 2026, rolled the top rate back from 35 percent to 20 percent for deaths on or after July 1, 2026, restoring the prior structure after the higher rates had applied for a single year to deaths on or after July 1, 2025. The schedule is graduated, starting at 10 percent on the first 1,000,000 dollars of taxable estate. Washington also reaches nonresidents who own Washington real estate or tangible personal property there.

So the retiree version of this corridor is a straight trade: stop paying up to 13.3 percent a year on pension, 401(k) and IRA distributions, which California taxes fully as ordinary income once you are a resident, and accept a state estate tax with a 3,000,000 dollar threshold that does not index and a 20 percent top rate, in place of no state estate tax at all. Whether that trade is good depends entirely on the ratio of your annual income to your net worth, and on how long you expect to live in the house. It is not a question the income tax rates can answer.

One thing genuinely does not change. Both states are community property states, so the characterization of marital property and the halving of community income survive the move intact. That is a simplification this corridor gets for free and the California-to-Texas and California-to-Nevada corridors also get, and it is worth knowing you do not need to re-plan around it.

Set this against moving from California to Texas and the contrast is the destination, not the origin. The California exit work is identical: the same closest-connections test, the same nine factors, the same FTB enforcement inventory, the same equity compensation workday ratio following you for years. What differs is what waits on the other side. Texas has no personal income tax, no capital gains excise tax, no enacted tax on high incomes pending in 2028, and no estate tax. A concentrated stock position sold as a Texas domiciliary produces no destination-state tax at all, which is the thing the Washington version cannot promise. If the whole point of the move is a liquidity event, the destination choice is not a tie.

Set it against moving from Oregon to Washington and the corridor reads completely differently even though the destination is the same. That move is a short one across a river, and the Washington abode-plus-183-day prong and the 30-day exception are built for exactly that geography, where someone can keep a Portland life and a Vancouver address without either one becoming decisive. Coming from California the distance does some of the work for you, in the same way it does on the Florida corridors: nobody accidentally accumulates 184 Washington days from Los Angeles, and nobody keeps commuting to a San Jose office from Seattle. The California-to-Washington risk is not ambiguity about where you are. It is the character of specific dollars.

Which is the honest summary. The residency question on this corridor is usually winnable, because the two states are far apart and the move is typically real. The sourcing questions are the ones that decide the money, and there are two of them pointing in opposite directions: California still owns the equity you earned there, measured by a workday ratio that can run for years after you leave, and Washington now taxes the gain on intangible property if you were domiciled there the day you sold. The move changes your address on both sides of that sentence and neither half of it depends on your address.

The Mobility Map records days and nights by state as they happen, which on this corridor answers two separate day questions. The first is the California side, where there is no safe number but where the section 17016 nine-month presumption and a closest-connections analysis both run on a presence record, and where FTB will reconstruct one from geolocation and card data if you have not kept your own. The second is the Washington side, where the RCW 82.87.020 prongs turn on more than 183 days with a place of abode, or on not more than 30 days for a departing domiciliary, with any portion of a calendar day counting as a full day in both counts.

Evidence Vault holds what this corridor actually asks for, and the equity file is the part most people do not think to keep. That means grant agreements, vesting schedules, exercise confirmations and the workday records behind them, because the FTB Publication 1004 ratio is arithmetic performed on which state you worked in on specific days years earlier. It also means the California closing statement or lease termination, the Washington driver license and vehicle registrations with their dates and the 30-day deadlines they ran against, the voter registration, the Form 540NR for the transition year, the Washington capital gains return for any year with a reportable long-term gain, and the documentation supporting a RCW 82.87.100(2) credit if you are claiming one.

AuditIQ surfaces retained California ties that keep generating dated records in a state with no statute of limitations on an unfiled year, and flags the pattern FTB audits most: a claimed move date sitting close to a liquidity event. Advisor sharing lets a CPA or tax attorney look at the presence record, the California-source equity items and the Washington domicile-at-sale question together, since a single sale date is the variable in all three at once.

ResidencyIQ organizes records and highlights potential exposure factors. It is not a law firm or an accounting firm and does not provide legal or tax advice; work with a qualified CPA or tax attorney on your own domicile, filings, and state exposure.

The Millionaires’ Tax, Engrossed Substitute Senate Bill 6346, is the source of the 9.9 percent rate on Washington taxable income above 1,000,000 dollars per household, the January 1, 2028 effective date with first returns and final payments due in 2029, the application to residents, part-year residents and nonresidents with Washington-source income, the shared 1,000,000 dollar standard deduction for spouses and domestic partners, the biennial inflation indexing starting in 2029, the federal adjusted gross income starting point with add-backs for capital gains taxes, incomplete non-grantor trust income and pass-through entity tax expense, and the non-refundable credits for capital gains tax, business and utility taxes, other state income tax and pass-through entity tax that cannot be carried forward. The analysis is from BDO: https://www.bdo.com/insights/tax/washington-enacts-millionaires-tax-changes-to-estate-taxation, with the signing announcement from the Office of the Governor: https://governor.wa.gov/news/2026/governor-ferguson-signs-millionaires-tax-law and additional practitioner coverage from Morgan Lewis: https://www.morganlewis.com/pubs/2026/03/washington-adopts-9-9-tax-on-residents-earning-over-1-million.

The April 2026 constitutional challenge filed in Klickitat County Superior Court, the plaintiffs including Benjamin and Lauren Petter, a Klickitat County farmer and a Kent trucking company owner, counsel Rob McKenna and Phil Talmadge, the uniformity and 1 percent maximum rate arguments, and the reliance on Culliton v. Chase (1933) for the proposition that income is property and can be taxed only at a low flat rate, are reported by The Spokesman-Review: https://www.spokesman.com/stories/2026/apr/09/opponents-sue-to-block-washingtons-new-millionaire/. The Washington Supreme Court’s unanimous order denying the Let’s Go Washington and Brian Heywood petition to force a referendum on ESSB 6346 as exempt from voter challenge, and the resulting repeal initiative on the November 2026 ballot, are covered by KOMO News: https://komonews.com/news/local/washington-supreme-court-blocks-challenge-on-new-millionaires-tax-citing-constitution-income-taxpayer-funding-benefits-mortgage-economy-cost-of-living-irs-housing-schools-seattle-olympia-ferguson-legal-challenge-microsoft-boeing and KUOW: https://www.kuow.org/stories/new-lawsuit-challenges-constitutionality-of-washington-s-new-millionaires-tax.

The capital gains excise tax under RCW 82.87, the exemptions for real estate, interests in privately held entities attributable to real estate, retirement account assets, condemned assets, certain livestock, depreciable business assets, timber and timberlands, commercial fishing privileges and franchised auto dealership goodwill, the standard deduction of 270,000 dollars for 2024 and 278,000 dollars for 2025 per individual, married couple or domestic partnership with annual inflation adjustment, and the filing deadline matching the federal return, are from the Washington Department of Revenue: https://dor.wa.gov/taxes-rates/other-taxes/capital-gains-tax. The tiered rates of 7 percent on the first 1,000,000 dollars and 9.9 percent above it, enacted by Engrossed Substitute Senate Bill 5813, Chapter 421, Laws of 2025, effective for tax year 2025 with returns due April 15, 2026, are from the Department’s special notice: https://dor.wa.gov/forms-publications/publications-subject/special-notices/new-tiered-rates-washingtons-capital-gains-tax. Quinn v. State of Washington, No. 100769-8 (Wash. 2023), holding 7 to 2 that the tax is a valid excise tax on the privilege of selling or exchanging capital assets rather than an unconstitutional tax on property or income, is at https://www.courts.wa.gov/opinions/pdf/1007698.pdf.

The RCW 82.87.020 definition of resident, including the domicile prong and its exception requiring no permanent place of abode in Washington for the entire taxable year, a permanent place of abode outside Washington for the entire taxable year, and not more than 30 days in the aggregate in the state, the alternative prong for a non-domiciliary who maintained a place of abode and was physically present more than 183 days, and the definition of a day as a calendar day or any portion of a calendar day, are at https://app.leg.wa.gov/rcw/default.aspx?cite=82.87.020. The Department of Revenue’s interim statement on the definition of domicile for capital gains excise tax allocation purposes is the source of the residence-in-fact-coupled-with-intent definition, the single-domicile rule, the presumption that Washington domicile continues and the taxpayer’s burden of proving a change, the requirement of physical presence plus intent at the new place, the nonexclusive factor list, the statement that selling your former home or acquiring a new one is not conclusive in establishing domicile, the rule allocating gain on intangible property to Washington where the taxpayer was domiciled in Washington at the time of the sale or exchange, and the citations to In re Estate of Lassin, 33 Wn.2d 163, 204 P.2d 1071 (1949), Ex parte Mullins, 26 Wn.2d 419, 174 P.2d 790 (1946), Sasse v. Sasse, 41 Wn.2d 363, 249 P.2d 380 (1952), Stevens v. Stevens, 4 Wn. App. 79, 480 P.2d 238 (1971) and In re Marriage of Strohmaier, 34 Wn. App. 14, 659 P.2d 534 (1983): https://dor.wa.gov/laws-rules/interim-statement-regarding-definition-domicile-capital-gains-excise-tax-allocation-purposes.

The RCW 82.87.100(2) credit for taxes paid to another taxing jurisdiction, its three conditions, the limit to total Washington liability with no carryback or carryforward, the proration method multiplying tax paid by the ratio of gain taxed in both states to total gross income in the other state, and the worked example producing a 812.72 dollar credit on 10,000 dollars of gain against 8,127.15 dollars of other-state tax, are from the Department’s interim statement: https://dor.wa.gov/laws-rules/interim-statement-regarding-capital-gains-excise-tax-and-calculation-credit-taxes-paid-another.

The Washington estate tax applicable exclusion of 3,076,000 dollars for deaths from January 1 through June 30, 2026 and 3,000,000 dollars for deaths on or after July 1, 2026, the statement that the amounts are not set to increase going forward due to an expired CPI provision in the statute, and the application to nonresidents owning Washington real estate or tangible personal property, are from the Department of Revenue: https://dor.wa.gov/taxes-rates/other-taxes/estate-tax. Engrossed Senate Bill 6347, signed March 24, 2026, rolling the top rate back from 35 percent to 20 percent for deaths on or after July 1, 2026 after the higher rates had applied for one year to deaths on or after July 1, 2025, and the graduated schedule beginning at 10 percent on the first 1,000,000 dollars of taxable estate, are described by Mercer Advisors: https://www.merceradvisors.com/personal-finance/washington-estate-tax-rates-roll-back-in-2026/ and the Senate Bill Report for ESB 6347: https://lawfilesext.leg.wa.gov/biennium/2025-26/Pdf/Bill%20Reports/Senate/6347.E%20SBR%20HA%2026.pdf.

The California definition of a resident under Revenue and Taxation Code section 17014 as anyone present in the state for other than a temporary or transitory purpose plus anyone domiciled in California who is outside it for a temporary or transitory purpose, the absence of a bright-line day count, the section 17016 presumption of residency for presence exceeding nine months, the nine-factor domicile analysis, and the section 17014(d) 546-day employment-contract safe harbor with its no-abode condition and 45-day annual visit allowance, are from FTB Publication 1031, Guidelines for Determining Resident Status: https://www.ftb.ca.gov/forms/2024/2024-1031-publication.pdf, with the FTB Residency and Sourcing Technical Manual at https://www.ftb.ca.gov/tax-pros/procedures/residency-and-sourcing-technical-manual-disclosure.pdf.

The apportionment of compensation for personal services to California in the manner reasonably attributable to services performed in the state, and the statement that one reasonable method is an allocation based on time worked, are in Cal. Code Regs. tit. 18, section 17951-5: https://www.law.cornell.edu/regulations/california/18-CCR-17951-5. The application of that method to equity compensation, including the ratio of California workdays to total workdays from grant to exercise for nonstatutory stock options, the grant-to-vest period for restricted stock units, and the exclusion of vacation days, holidays and weekends from total workdays, is FTB Publication 1004, Equity-Based Compensation Guidelines: https://www.ftb.ca.gov/forms/misc/1004.html, with a worked example of a California-to-out-of-state mover producing a 50 percent California allocation of a 750,000 dollar exercise spread from Reed Corporation: https://reedcorp.tax/helpful-guides/california/california-stock-option-allocation/.

Appeals of Stephen D. Bragg, 2003-SBE-002 (Cal. State Bd. of Equalization, May 28, 2003), Nos. 110567 and 119357, is the source of the approximately April 1, 1993 move to an Arizona cattle ranch, the holding that Bragg was a resident of Arizona in 1993 and had left California for other than a temporary or transitory purpose, the rejection of his 1997 amended return claiming full-year California residency, the 1988 sale of his interest in Bragg Investment Company and the covenant not to compete paying 1,333,333 dollars a year with a community property half of 666,666.50 dollars, the holding that the covenant income was California-source, the 84.05 percent apportionment under the three-factor formula adopted in Appeals of Milhous (2000-SBE-003), the assessments of 48,153 dollars for 1993 and 42,658 dollars plus a 10,664 dollar late filing penalty for 1995, and the nineteen-factor closest-connections list known as the Bragg factors: https://ota.ca.gov/wp-content/uploads/sites/54/2022/03/03-sbe-002-Bragg_rs.pdf.

The California top marginal rate of 13.3 percent including the 1 percent Mental Health Services Tax above 1,000,000 dollars, the combined 14.6 percent top rate on wage income once the uncapped payroll tax is included, the 7.25 percent state sales tax averaging 8.99 percent combined, the 0.70 percent effective property tax rate on owner-occupied housing value, state and local collections of 8,942 dollars per capita, the absence of a California estate or inheritance tax, and California’s 48th place ranking on the 2026 State Tax Competitiveness Index are from the Tax Foundation: https://taxfoundation.org/location/california/. Washington’s absence of a tax on wages, the 9.9 percent tax on household income above 1,000,000 dollars taking effect in 2028, the 6.50 percent state sales tax averaging 9.51 percent combined, the 0.75 percent effective property tax rate, state and local collections of 7,745 dollars per capita, the Business and Occupation gross receipts tax in place of a corporate income tax, and Washington’s 45th place ranking on the same index are at https://taxfoundation.org/location/washington/.

The California exit stickiness and audit aggressiveness ratings, the Washington ratings, the FTB concentration of residency audits on high earners whose departure date lines up with a liquidity event and the late-December-move-then-January-gain trigger, the four-year assessment period for a filed return against no statute of limitations at all for a year with no return filed under R&TC section 19057(a), the typical audit lookback opening with the year of the claimed move, the informal 15,000 to 75,000 dollar defense cost range, the enforcement method inventory including geolocation and card data, 1099s and K-1s issued to a California address, DMV and voter file cross-checks, declared-homestead cross-referencing, social media, utility activity, informant tips and private investigators, the treatment of California capital gains as ordinary income with no preferential long-term rate, the full taxation of pension, 401(k) and IRA distributions to residents, the Proposition 13 and Proposition 19 property tax mechanics, the trailing-income rules for deferred compensation under 4 U.S.C. section 114 and for California business and real property income, the Form 540NR part-year filing requirement, the Washington 30-day driver license and vehicle registration deadlines, and the community property status of both states come from ResidencyIQ’s own dossier research, with underlying citations on the California and Washington residency guides.