Moving Out of California with Unvested Equity: The Trailing Nexus Problem

You moved from San Francisco to Austin in March. By April the next year, you find out that California still wants to tax the RSUs that vested in November, nine months after you left. This is not a mistake. Under California’s trailing nexus rules, equity compensation earned partly while you were a California resident is taxed by California to the extent the service period overlapped California residency, regardless of where you lived at vest.

The rule comes from Publication 1005 of the California Franchise Tax Board, which treats equity compensation as compensation for services performed and sources it based on workdays during the vesting period. California is one of the most aggressive states in enforcing this. The Franchise Tax Board audits high-earner departures routinely and the audit-win rate for the state is high because the underlying math is defensible.

This guide covers the trailing nexus rule in detail, the workday apportionment mechanics, what the Franchise Tax Board actually looks at during a residency audit, and the specific moves that make your California tax position defensible when you leave.

The source-of-income rule for equity

California Revenue and Taxation Code §17041 taxes California residents on all income from whatever source. California nonresidents are taxed on California-source income only. For nonresidents, California-source income includes compensation for services performed in California.

For equity compensation that vests over time, the Franchise Tax Board applies a workday apportionment: the portion of the vesting gain attributable to California-residency workdays during the vesting period is California-source income, regardless of residency at the vest date.

Example. Employee granted 4,000 RSUs on January 1, 2023 while a California resident. 25% vest annually. Employee moves to Texas on July 1, 2024. The third vest (January 1, 2026) at $100 per share:

Period	Residency	Workdays (approx)
Jan 2023 - Jun 2024 (18 mo)	California	378
Jul 2024 - Jan 2026 (18 mo)	Texas	378

The third vest is 100,000 / 756 × 378 = 50% California source. $100,000 vest, $50,000 California-source, California tax owed at up to 13.3% = ~$6,650.

The fourth vest (January 2027) at whatever price it is has 378/1134 = 33% California source. Each subsequent vest has less California exposure as the California-residency portion becomes a smaller fraction of the total service period.

Option exercises and the same rule

For options (ISO and NSO), California applies the same workday apportionment but the service period runs from grant to exercise (for NSOs) or from grant to the earlier of vest or exercise (for ISOs, with adjustments for the AMT treatment).

An NSO granted while a California resident, exercised years later as a nonresident, produces California-source ordinary income on the exercise-date spread to the extent California workdays during the service period represent a fraction of the total. Exercising a long-held NSO as a Texas resident may produce a surprising California tax bill.

For ISOs, the AMT spread is similarly apportioned. California has its own AMT system, and California AMT on ISO exercises by former residents is common and often overlooked.

The residency-change mechanics

“Moving to Texas” is not the same as “becoming a Texas resident for California tax purposes.” California uses a domicile-plus-physical-presence test. The key concepts:

Domicile. Your permanent home, the place you intend to return to indefinitely. You can only have one domicile at a time. Changing domicile requires both physical presence in the new location and a demonstrable intent to make it permanent.

Residency. For California tax, residency follows domicile in most cases. Non-domiciled individuals can still be California residents if they are in California for more than 9 months of the tax year (the 9-month presumption under §17014).

Physical presence. California tracks days of physical presence. More than 546 days in California during any 18-month period creates a presumption of residency.

Moving out requires changing all of these. Selling the California home, registering to vote in Texas, moving drivers’ license and vehicles, changing doctors and dentists, changing mailing addresses, moving personal property, and shifting professional relationships (lawyer, accountant, broker). The Franchise Tax Board will look at all of these in a residency audit.

What the Franchise Tax Board audits

The FTB’s residency audit protocol, documented in their publications and audit manual, looks at a long list of “connections” in both directions. Key ones:

California connections the FTB looks for:

• Real property ownership (especially a prior residence retained as a rental or vacation home)
• California driver’s license or voter registration
• Presence of spouse or children still in California
• California doctors, dentists, attorneys, accountants
• California utilities, subscriptions, club memberships
• Vehicle registration in California
• Mail forwarding from a California address
• Time spent in California (days tracked aggressively)

New-state connections the FTB expects you to have if you claim non-residency:

• Owned or leased permanent home in new state
• Drivers’ license and vehicle registration in new state
• Voter registration in new state
• Employment or business activity primarily in new state
• Presence of immediate family in new state
• Professional advisors (doctor, lawyer, accountant) in new state

A partial move (keeping the California home, keeping the California drivers’ license, traveling back to California frequently) usually fails the audit. The FTB will conclude California residency continued, and tax the entire year’s income at California rates. This has happened to many tech executives who did not fully commit to the move.

Documentation that survives audit

The best defense against an FTB residency audit is contemporaneous documentation of the move. Not retrospective; contemporaneous.

Minimum documentation package:

• Closing statement on California home sale or lease termination.
• Lease or purchase documents for new-state home, dated before or concurrent with California departure.
• New-state drivers’ license issued with date.
• Voter registration in new state.
• Utility bills in new state showing continuous service.
• Mail forwarding from California address with USPS confirmation.
• Employer letter confirming remote work from new state or transfer.
• Phone records showing phone number transferred or primarily used in new state.
• Bank statements showing ATM usage primarily in new state.
• Travel records (flights, hotels) documenting time in vs out of California.

Days-in-state log. Keep a calendar noting which state you were in on each day for at least the three years following the move. The FTB will ask for this, and being able to produce it credibly shifts the audit significantly.

Special cases: spouse stays behind, kids in California school

One of the hardest fact patterns is a family where one spouse (often the non-primary-earner or the one with the less portable job) stays in California while the other moves to a new state. The FTB treats the spouse staying in California as a strong indicator that the family domicile remains California.

For tech families where one spouse is pursuing a new role remotely and the other spouse and children stay in the Bay Area for school, the FTB will typically audit and win. The California-resident spouse’s income is obviously taxed, but the FTB will also argue the “departed” spouse remains a California resident for income tax purposes.

Options: coordinate a full family move before any income is shifted out of state; treat the stay-behind period as California-resident (pay California tax on everything) and shift only after the family fully relocates; or file as “California resident” and “nonresident” spouse separately, which is technically permissible but rarely stands up in audit.

Other high-nexus states

California is aggressive but not unique. New York applies similar workday apportionment rules for equity compensation earned while a New York resident. The 548-day rule creates statutory residency based on physical presence even without domicile change.

New Jersey, Connecticut, Massachusetts, and Illinois all have meaningful trailing taxation of equity compensation. Washington has no state income tax but added a capital gains tax in 2022 on gains above $250k.

Texas, Florida, Nevada, Tennessee, Wyoming, Alaska, South Dakota, and New Hampshire have no state income tax. Moves to these states are the cleanest from a state-tax perspective, but only if the move is complete.

Frequently asked

How long should I wait after moving before selling? Generally 12 months of clear nonresidency is defensible. 24 months is safer. For large sales (QSBS, concentrated stock, company acquisition), coordinate the sale date with tax counsel well after the move.

Can the FTB come back years later? The California statute of limitations is four years from the filing date, extended to six years if more than 25% of income was omitted. For significant equity events, assume the audit window runs at least four years and keep documentation accordingly.

What if I have a remote California employer after I move? California sources income to where services are performed. If you are living in Texas and performing all work in Texas for a California employer, the wages are Texas-source. But the California employer may still report wages as California source on the W-2; you will need to file California Form 540NR claiming nonresident status and correcting the source.

Does California tax Social Security or retirement withdrawals for former residents? No. Pension and Social Security income is generally sourced to the recipient’s current state of residence, not the state where the underlying work was performed. California does not tax nonresidents on pension or retirement income from California employers.

What about QSBS gains after I move? California does not conform to §1202 QSBS exclusion. California taxes QSBS gains at full rates regardless of federal exclusion. Moving out of California before selling QSBS is one of the higher-leverage planning moves available because the California tax (up to 13.3%) is avoided if the move is valid.

Next step

If you are considering a move out of California, plan the timing around known future equity events. The California trailing tax calculator estimates how much California tax survives the move for each unvested grant. Engage a California-licensed CPA and, for high-stakes cases, a state-tax attorney before the move, not after. Residency audits are won or lost on the documentation assembled at the time of departure.