State RSU Vesting at Relocation: California Sourcing Rules at $1M Unvested

The core trap: residence at vest does not control

Federal tax law treats RSU vesting as an ordinary income event under IRC sec. 451 — the FMV at vest becomes W-2 income on the employee’s federal return regardless of state. The state tax analysis is more complicated. Most states tax compensation income based on the employee’s residence at the time the income is recognized. California is different. California taxes RSU income (and most other deferred compensation) based on where the services were performed during the vesting period — even if the employee no longer lives in California when the shares vest.

The mechanism is Cal. Code Regs. tit. 18 sec. 17951-5, supplemented by FTB Publication 1004 (multi-state allocation guidance for compensation). The combined framework requires non-resident employees with California-period vesting to file California non-resident returns (Form 540NR) reporting the California-source portion of their equity income.

The California Franchise Tax Board (FTB) has the authority under California Revenue and Taxation Code sec. 19031 to audit non-resident returns. The FTB has issued multiple enforcement notices targeting tech employees who relocated from California to Texas, Washington, Nevada, and Florida without continuing to report California-source RSU income.

The working-day allocation formula

The mechanical formula under sec. 17951-5 and Publication 1004:

CA-source income = (CA workdays during vesting period) / (Total workdays during vesting period) × RSU FMV at vest

Each individual RSU grant is calculated separately because each grant has its own vesting schedule and working-day count. A typical tech-employee equity stack includes 4-6 active grants with different vesting calendars — and the California allocation differs for each.

Counting workdays

FTB Publication 1004 prescribes simplifying assumptions for counting workdays:

• Standard year: 5 working days per week × 52 weeks = 260 days, less holidays and vacation = approximately 240-250 actual working days.
• Each day allocated to one location. Working remotely from another state counts as a non-California workday even if the employer is California-based.
• Business travel days. Days spent traveling to California for meetings or work count as California workdays. Days spent traveling away from California for business count as non-California workdays.
• Weekends and holidays. Generally excluded from the count, but specific work events on weekends (a Saturday off-site in California) count.
• Paid leave. Days of paid vacation or sick leave are typically allocated proportionally to the employee’s usual work location — not zeroed out.

Multi-grant allocation

An employee with multiple RSU grants must compute the allocation separately for each:

The earliest grant (longest pre-relocation history) typically has the highest California allocation. The most recent grant (most days worked post-relocation) has the lowest. Each tranche at vest carries its grant’s California percentage.

Worked example: $1M unvested RSUs across the relocation

Priya is a senior engineering manager who worked in San Francisco for 8 years before relocating to Austin in September 2026. She has $1 million of unvested RSUs at the time of the move:

• Grant A: $400K granted January 2023, 4-year vest with 1-year cliff, quarterly tranches thereafter. 21 months of vesting completed pre-move, 27 months remaining.
• Grant B: $400K granted January 2025, 4-year vest with 1-year cliff. 20 months of vesting completed pre-move, 28 months remaining.
• Grant C: $200K granted July 2026, 4-year vest with 1-year cliff. 2 months of vesting completed pre-move, 46 months remaining.

Priya’s federal marginal bracket: 35% MFJ ($394K-$501K). California top rate while resident: 13.3%. Texas: no state income tax.

California allocation by grant at full vest

California tax due across the vesting years

Priya owes California tax on the $350,000 California-source RSU income spread across the years 2027-2030 as each tranche vests. Approximate California tax bills:

• California top rate 13.3% applies above $698,272 (MFJ) — Priya’s blended California income with the RSU allocation usually keeps her in 11.3-12.3% range
• Estimated California tax: $350,000 × ~12.5% blended = approximately $43,750 across the vesting period
• At the highest CA bracket, the total could exceed $46,500 if her California-source income compounds with other CA-source compensation (board fees, consulting)

If Priya had stayed in California through full vest, her California tax on the entire $1 million would have been roughly $115,000-$125,000. The relocation saves approximately $70,000-$80,000 in California tax — but it does NOT eliminate the $43,750 California exposure on the pre-relocation work portion. The standard misconception (“I moved, so California is done”) costs employees five-figure underpayments in audit assessments.

The residence-vs-source dual taxation problem

California claims tax on the source portion of RSU income. Other states may also claim tax based on residence at vest. Most states (including Texas, Washington, Nevada, Florida, Wyoming, Tennessee, South Dakota, Alaska, New Hampshire) have no state income tax — so there is no overlap and the California source claim is the only state-level tax.

For relocations from California to other states with income tax, the analysis is more complex. The destination state typically taxes residents on all income (resident tax) but provides a credit for income taxed by the source state. New York, for example, generally allows a resident credit for tax paid to California on California-source RSU income — but the credit is limited to the lower of the two states’ rates on the income. Multi-state filings are required.

States that follow source-state principles like California

California is the most aggressive state in sourcing deferred compensation to the work-period state, but other states use similar frameworks for RSU and stock-option income:

• New York: TSB-M-95(3)I and TSB-M-07(7)I source RSUs and options based on workdays during the grant-to-vest period. Similar percentage-allocation methodology.
• New Jersey: taxes nonresidents on compensation for services performed in NJ, including pro-rata equity compensation under N.J.S.A. 54A:5-8.
• Massachusetts: applies a working-day allocation under 830 CMR 62.5A.3 for nonresidents.
• Oregon, Pennsylvania, Connecticut, Maryland, Illinois, Virginia: all apply some form of source-state taxation on RSUs and options for nonresidents based on work location during the vesting period.

States without income tax cannot claim source taxation on their own residents (because there is no state tax to apply), but residents who worked in source-tax states during the vesting period still owe those source-state taxes after relocation.

FTB Publication 1004 documentation requirements

The California FTB expects contemporaneous documentation of relocation timing and work locations. Strong audit defense requires:

• Relocation letter from employer specifying the new work location, effective date, and confirming the change is permanent.
• Lease or home-purchase documentation in the destination state, dated.
• Utility activation dates, driver’s license update, voter registration at the new address, all aligned with the move timeline.
• Payroll records showing the change in state withholding to the new state.
• Employer travel logs or expense reports documenting business travel back to California after the move.
• Personal calendar or work-from-home/work-from-office logs for the vesting period.

The FTB has the authority to challenge a self-reported allocation. Without contemporaneous documentation, the FTB defaults to assuming full California sourcing — and the burden is on the taxpayer to prove otherwise.

The travel-back-to-California problem

Many tech employees relocate but continue to travel to California regularly for meetings, conferences, or quarterly on-sites. Under FTB Publication 1004, every workday spent in California (regardless of residence) counts as a California workday for sourcing purposes.

Practical implication: an employee who relocates to Texas but travels 8 days per month to the San Francisco headquarters works approximately 96 days per year in California. Out of 240 annual workdays, that is 40% California allocation on the post-move vesting period. The relocation did not save 100% of post-move California tax — it saved 60%.

Companies that want to minimize this exposure on behalf of relocated employees often shift to a remote-default work arrangement, deliberately reducing California office time. Other companies treat California time as the employee’s problem and document the work-location split for payroll withholding only.

Timing the relocation for tax efficiency

Several timing levers can compress California source-state exposure:

1. Relocate early in a vesting period

New grants issued AFTER the relocation have zero California allocation (assuming no California work post-move). Grants issued just before relocation have minimal pre-move work and therefore minimal California allocation. The grants with the highest California allocation are the long-tenured grants where most of the vesting period occurred in California.

Strategic implication: if your employer typically issues annual refresh grants, time the relocation just BEFORE the next refresh grant. The new grant starts with the new state allocation; the old grants continue to bleed off California allocation as their remaining vest periods accumulate non-California workdays.

2. Lump-sum acceleration before relocation

Some employers permit accelerated vesting at termination or with executive approval. Accelerating RSUs WHILE still a California resident converts unvested RSUs into vested shares and recognized income at California rates — but it locks in the income event while you are still a resident with the same rate exposure you already faced. The benefit: no future California source-tax problem on those shares. The cost: paying tax upfront on unvested grants that might otherwise have vested across multiple years at lower marginal rates.

Acceleration rarely makes net tax sense unless the relocation is to a high-tax state where the destination state’s rate would have been higher than California’s — extremely rare scenario in 2026.

3. Modified work-from-home schedule pre-move

Employees who can work remotely from outside California for part of the vesting period BEFORE the formal relocation can begin reducing California allocation early. The FTB requires actual work to be performed outside California — vacation time and personal travel do not count. Documented remote work from a non-California location (e.g., a vacation home in Lake Tahoe is California; a remote summer working from a family home in Texas is not California) counts toward the non-California workday count.

The employer-payroll-withholding tension

After relocation, most employers update payroll withholding to the new state — meaning no California state tax is withheld from regular paychecks. This creates a gap: California source tax is still owed on RSU vesting, but no California withholding occurs to cover it.

Two practical approaches:

• Request supplemental California withholding on RSU vest events through the employer’s payroll system. Many large employers can specifically withhold California tax on the California-source portion of vesting events.
• Make California quarterly estimated tax payments on Form 540-ES to cover the projected source-state liability for the year. Underpayment penalties apply if estimated payments are insufficient.

Failure to pay California quarterly estimates produces penalty interest at California’s underpayment rate (currently approximately 8% annualized) plus potential California-source filing penalties.

Relocating to no-tax states: the strategic math

Texas, Florida, Nevada, Washington, and Tennessee are the most common destinations for California tech-employee relocations. The post-move tax savings depend on the proportion of remaining vesting that happens post-move.

The relocation saves the most California tax when it happens EARLY in the vesting period. Late-vest relocations (90%+ already worked in California) save very little — California still claims 90% of the income at the same rate as if the employee stayed.

The Form 540NR filing obligation

Non-residents with California-source income must file California Form 540NR (Non-Resident or Part-Year Resident return). The 540NR includes a worksheet (Schedule CA-NR) for allocating compensation income between California and non-California sources. The form is due by April 15 of the year following the income year, with the same extension provisions as the federal return.

Critical: California can audit Form 540NR returns going back 4 years. Employees who relocated and did not file 540NR returns are still on the hook for the California source-state tax — plus penalty interest at California rates. The FTB has aggressively pursued non-resident filing compliance for high-income relocations, particularly when the employer is California-based.

Coordination with federal withholding and supplemental income reporting

RSU vesting triggers W-2 income reporting under IRC sec. 451 at the FMV on vest date. Employers report the income on the employee’s W-2 regardless of which state is the source. Most employers default federal supplemental withholding to 22% on RSU income (37% on amounts above $1 million in a calendar year per IRC sec. 3402(p)).

The federal withholding rate is independent of state allocation. State withholding depends on the employer’s payroll system — some employers correctly split state withholding between California and the new state based on the work-allocation; others default to the new state only. Verify your withholding setup with the payroll team immediately after relocation.

Key takeaways

• California sources RSU income based on the proportion of the vesting period during which services were performed in California — not residence at vest. Under Cal. Code Regs. tit. 18 sec. 17951-5 and FTB Publication 1004, the working-day allocation determines the California-source percentage.
• On $1 million of unvested RSUs with 50% California work-period allocation, California claims $500,000 of source income — approximately $50,000-$65,000 of California tax depending on the bracket, owed even after relocation to a no-tax state.
• The relocation savings are highest when the move happens early in the vesting period. Moves in the final months of a vesting period save very little California tax because most of the work already occurred in California.
• Document the relocation thoroughly: relocation letter, new lease or home purchase, updated driver’s license and utilities, payroll withholding change, business travel logs. The FTB defaults to full California sourcing without contemporaneous documentation.
• Travel back to California for work after the move counts as California workdays in the allocation. Frequent on-site travel can significantly increase the California source allocation even after a permanent move.
• Non-residents with California-source income must file Form 540NR. Failure to file does not eliminate the California tax obligation — the FTB can assess back-tax plus penalty interest for up to 4 years.
• Coordinate state withholding immediately after relocation. Many employers default to single-state withholding (new state only) — leaving the California source-state tax obligation unfunded and subject to quarterly estimated tax penalties.