California residency and founder equity

A California founder with $10M in exit proceeds could owe $1.33M in state taxes that a nonresident would owe nothing on — if the move happens before the right year.

California taxes long-term capital gains as ordinary income, at rates up to 13.3%.¹ There is no preferential rate for long-term gains at the state level, unlike the federal system's 0%/15%/20% brackets. For a founder with a large equity stake, this is not a rounding error — it is often the single largest financial variable that advance planning can change.

The planning opportunity: capital gains from selling stocks and other intangible property are not California-source income for nonresidents. If you are a genuine nonresident in the tax year you recognize the gain, California's claim on that gain largely disappears. The question is whether you can establish nonresident status that survives FTB scrutiny before the exit year begins.

How California determines where you live

California uses a two-part framework to determine taxability.² First, it determines whether you are a resident — broadly defined as someone who is in California for other than a temporary or transitory purpose, or who is domiciled in California but is outside it temporarily. Second, for those who are not full-year residents, it applies income-sourcing rules that determine which items are California-source income taxable to nonresidents.

Domicile is your permanent home — the place you intend to return to when you are away. You can have only one domicile at a time. Changing it requires: (1) physically leaving your old domicile; (2) establishing a fixed abode in a new location; and (3) having the genuine intention to make that place your permanent home, with no fixed intention to return.³

The nine factors the FTB weighs

California does not use a simple day-count rule as the primary domicile test. It uses a closest-connections analysis across nine factors from FTB Publication 1031.³ No single factor is dispositive — the FTB weighs all of them together:

In practice, the factors with the greatest weight in audits are: where your immediate family lives, where your principal home is, and how many days per year you spend in California. If your spouse and children remain in the CA home and your children stay in California schools, auditors will typically conclude your domicile did not change regardless of your own physical location.

The income-sourcing rule for founder stock

Even if California accepts your nonresident status, it retains the right to tax California-source income. The source rules vary by income type.⁴

Capital gain from intangible property — including publicly traded stock and private company shares in a C corporation — is sourced to the taxpayer's state of domicile. It is not California-source income for nonresidents. A genuine nonresident who sells founder stock recognizes capital gain that California has no legal claim on.⁴

This is the core of the planning: if the founder's exit proceeds are capital gain (not compensation), and the founder is a genuine nonresident when the gain is recognized, California gets nothing on the appreciated value.

How different equity types interact with the sourcing rules

Founder common stock (83(b) election at incorporation): The founder received stock at near-zero FMV at incorporation, filed an 83(b) election, and paid nominal tax on the small compensation element at grant. All subsequent appreciation is long-term capital gain after the holding period is met. As a nonresident, this capital gain is not California-source. This is the cleanest planning scenario — establish genuine nonresident domicile before the exit year, and California's exposure on the appreciated founder stock disappears.

Incentive Stock Options (ISOs): The spread between the strike price and the 409A value at exercise has a California-source compensation component for the portion of the vesting period worked in California. This is calculated by a workday allocation: (CA workdays during vesting period ÷ total workdays during vesting period) × total spread. Even as a nonresident at exercise, that CA-allocated portion of the spread can remain taxable. However, the capital gain above the exercise price (FMV at exercise) is intangible income sourced to domicile — not CA-source for nonresidents. The practical implication: move before exercising ISOs with a large spread, and the CA compensation element calculation resets from the date of departure.

NSOs: The spread at exercise is compensation income allocated to California based on CA workdays during the vesting period. This allocation applies even after you become a nonresident, for the portion earned while a CA resident. Capital gain above the NSO exercise price is intangible income — not CA-source for nonresidents.

When you must complete the move

The relevant tax year is the one in which you recognize the gain. For a founder selling stock in an acquisition closing in March 2027, the relevant year is 2027. Establish nonresident domicile before January 1, 2027 — ideally with the change complete and documented well before year-end 2026.

Moving in the same year as the exit still reduces exposure, but it creates a part-year California return requiring precise documentation of the departure date. You owe California tax on all income recognized while a California resident in that year. A pre-year-end departure means only income from after the departure date escapes; an acquisition closing in the first week of a new year where you became a nonresident in October of the prior year is the cleanest scenario.

The announcement problem

The FTB is specifically aware that founders sometimes announce a move after an exit is in motion. A departure that looks suspiciously timed — move to Texas in September, acquisition closes in November — will draw scrutiny. Auditors ask: was this a genuine change of domicile, or tax avoidance dressed as relocation?

The answer depends on whether your life actually changed, not just your paperwork. Auditors will request phone records, credit card statements, and boarding pass data to verify where you physically were during the claimed transition period. Obtaining a Nevada driver's license while your cell phone pinged Palo Alto every weekday does not establish nonresident status.

Steps to establish a new domicile

The FTB expects to see a real life change — not a paperwork exercise. The following steps create both the factual record and the documentation trail that domicile has shifted:⁵

1. Establish physical residence in the new state. Purchase or lease a home that is your primary dwelling — not a secondary vacation property. The size and permanence of the new home relative to any retained California property matters. A studio apartment in Austin while keeping a 4,000-square-foot Bay Area home undermines the claim.
2. Obtain a driver's license in the new state. Surrender your California license. Most states require license transfer within 30–90 days of establishing residence.
3. Register to vote in the new state. Cancel California voter registration. This is one of the clearest objective signals of permanent intent.
4. Register vehicles in the new state. Transfer vehicle registration promptly. California requires re-registration within 20 days when a new resident moves in; the same logic works in reverse.
5. Open bank accounts in the new state. Establish primary banking in the new state. ATM and debit card transaction geography is data auditors review.
6. Transfer professional licenses and memberships. Move your professional licenses, bar membership, or other registrations to the new state. Cancel California club memberships, gym memberships, and civic associations.
7. Sell or rent out the California home. Retaining a large California home as a vacation property while claiming a smaller new-state property as your primary residence will undermine the domicile argument. Rent it out at minimum; sale is cleaner.
8. Relocate your immediate family. This carries more weight than any other single step. If your spouse and children remain in the California home and your children remain enrolled in California schools, auditors will likely conclude that your domicile did not change regardless of your own physical presence elsewhere.
9. Notify relevant parties. Update your address with the IRS, SSA, brokerage accounts, and banks. These administrative changes create a contemporaneous paper trail.
10. File a part-year California return for the year of departure. Report California income through the departure date; report non-CA income for the remainder. This establishes the departure date on the official record.

What a California residency audit looks like

The FTB has a dedicated audit unit for high-income departures. Audits typically begin within 1–3 years after the tax year in question and take 12–18 months to resolve. An Information Document Request (IDR) will typically seek:⁵

• Monthly cell phone records (call logs and in some cases tower ping data)
• All credit and debit card statements showing where purchases were made
• Airline boarding passes and frequent flyer records
• Hotel and lodging receipts for the transition period
• Business calendars, board meeting invitations, and investor communications
• Medical, dental, and professional service records (where you received care)
• Property records and utility bills for all homes maintained
• Social media posts and photos with geolocation data

Build your documentation file as you make the move — contemporaneous records are significantly stronger than reconstructed timelines assembled two years later after receiving an audit notice. A calendar or daily log maintained during the transition period is one of the most useful pieces of evidence an auditor can see.

What the move does not eliminate

A genuine residency change eliminates California's claim on capital gain from intangible property sourced to your new domicile. It does not:

• Eliminate California-source compensation income already earned. If you worked in California during the vesting period for ISOs, NSOs, or RSUs, the CA-allocated compensation element remains taxable by California even after you move out of state.
• Override income recognized before your departure date. Income earned while still a California resident in the year of departure is still taxable in California regardless of what happens later in that year.
• Reduce taxes on California real estate or California business income. Rental income from California property, California S-corp income, and income from a California business remain California-source for nonresidents. The move addresses founder stock specifically.
• Apply retroactively to a deal already under a binding agreement. If you signed a definitive merger agreement as a California resident in a given tax year, California will argue that the right to income was fixed at that signing. Pre-close residency moves are legally cleanest before any binding agreement is in place.

The QSBS dimension

California does not conform to the federal § 1202 exclusion. Even if your federal gain is fully excluded under the post-OBBBA rules — 100% exclusion after a 5-year hold, up to the $15M per-issuer cap — California taxes the full gain at ordinary income rates up to 13.3%.⁶

For a genuine nonresident, however, this California non-conformity becomes irrelevant. The capital gain is not California-source income regardless of whether it is federally excluded or not. The state residency move and QSBS planning are complementary: both reduce the tax on the same dollar of gain. A California founder with QSBS-qualified stock who becomes a nonresident before the exit can eliminate both the federal capital gains tax (via § 1202) and the California tax (via nonresident status) on the qualifying gain — a potentially very large combined benefit.

The proposed "exit tax" and what current law actually says

Several California legislative proposals have attracted attention by proposing a wealth-based tax on former high-income residents — one version would follow a departing founder for up to 10 years. As of June 2026, no such law has been enacted. Current California law taxes income, not accumulated wealth, based on residency in the year income is recognized. A genuine nonresident who recognizes capital gain on intangible property in a future year owes no California tax on that gain under current law. This is worth monitoring, but it is not the current legal landscape.