RSU Multi-State Allocation Explained: Workday Fraction Method

Why RSU Income Gets Split Across States

RSU income is compensation for services performed over the vesting period — not a windfall that occurs only on vest day. States treat it as income earned across the entire service period from grant to vest, and they tax the portion of that income attributable to services performed within their borders during that period. This "source-based allocation" principle means that where you worked, not just where you lived on vest day, determines who taxes what portion of the income.

The practical consequence: moving from a high-tax state to a no-tax state before your RSUs vest does not eliminate the high-tax state's claim on the portion earned while you lived and worked there. California is the most aggressive practitioner of this rule, with the most detailed published guidance (FTB Publication 1004 and the Residency and Sourcing Technical Manual). New York follows a similar approach but with a unique 14-day de minimis threshold. Most other income-tax states apply a workday-fraction method based on their general non-resident income allocation rules, without a specific equity compensation regulation.

The allocation also applies in reverse. If you joined a company as a Texas resident and later moved to California, the California FTB will claim only the California-period fraction — not the Texas-period fraction. Your W-2 for the vest year should reflect the California-sourced income in Box 16 (state wages), and you file a California non-resident or part-year resident return for that portion. This sourcing calculation is separate from and independent of federal income tax — the federal tax treats the entire vest value as ordinary compensation income in the year of vesting, regardless of multi-state allocation.

State-by-State RSU Allocation Grid

The table below summarizes how the 14 most commonly relevant states treat RSU vest income for non-residents who worked in the state during the grant-to-vest period. No-tax states are included to confirm their zero-claim status. Always verify with the specific state's non-resident return instructions before filing.

Sources: CA FTB Publication 1004, NY TSB-M-12(5)I, NY TSB-M-95(3)I, state non-resident return instructions — May 2026. Always verify with current state guidance before filing; non-resident RSU allocation rules can change with legislative or administrative action.

The Workday Fraction Formula — Step by Step

The core formula is the same across all states that use the workday-fraction method. The inputs vary by state in terms of how workdays are counted (whether to exclude PTO, sick days, and holidays) and when the period begins and ends.

The "total workdays in the grant-to-vest period" is the denominator for all states. It is calculated as the number of weekdays you actually worked during the period from the grant date to the vest date — typically excluding weekends, holidays, and PTO days depending on the state's specific rules. California's guidance (FTB Publication 1004) explicitly uses workdays, not calendar days of residency. A California resident who was on a 3-month unpaid leave during the grant period would not count those weeks as California workdays — reducing the denominator and potentially increasing (or decreasing) the California fraction depending on where the leave fell in the timeline.

Step-by-Step: How to Calculate Your Multi-State RSU Allocation

Real-World RSU Multi-State Allocation Scenarios

Scenario 1: California to Texas Move — The Trailing Tax Surprise

Scenario 2: California to New York Move — Two States Both Claim a Share

Scenario 3: New York 14-Day Rule — The One-Visit Exemption

Scenario 4: Four-Year Vesting with Quarterly Tranches — Multi-State Across All Tranches

California-Specific RSU Rules — FTB Publication 1004 Detail

California's Franchise Tax Board has the most detailed published guidance on equity compensation sourcing of any state in the US. FTB Publication 1004 (Equity-Based Compensation Guidelines) and the Residency and Sourcing Technical Manual (Rev. 01/2026, Section 3275) together form the authoritative framework.

Sources: CA FTB Publication 1004 (current version at ftb.ca.gov/forms/misc/1004.html); CA Residency and Sourcing Technical Manual §3275 (Rev. 01/2026); FTB.ca.gov — May 2026.

RSU vs Stock Options vs ESPP — Does the Workday Fraction Apply to All?

What the Workday Fraction Covers — and What It Does Not

Who Needs to Understand RSU Multi-State Allocation?

• Technology employees who received grants while in California and subsequently moved — California's FTB is the most aggressive tax authority in the country for trailing RSU income. A technology engineer who received a 4-year cliff grant in San Francisco in 2022 and moved to Seattle in 2024 will owe California non-resident income tax on approximately 50% of the vest income in 2026, even though they have not lived in California for two years. California does not require you to be a current resident to tax California-period income — it follows the workday fraction indefinitely. Every year that California-period grants continue to vest, a California Form 540NR is required.
• Executives and senior engineers who relocated before a major vest event or IPO liquidity event — large single-vest events — cliff vesting grants, IPO RSU releases, change-of-control accelerations — can produce hundreds of thousands or millions of dollars of vest income in a single tax year. The state allocation on a $1 million cliff vest with a 75% California fraction is $750,000 of California non-resident income at California's top rates (up to 13.3%), generating approximately $80,000–$100,000 in California non-resident income tax. The FTB audits large vest events proactively — W-2 Box 16 figures that do not match the FTB's calculation of the California-sourced amount will trigger a correspondence notice or field audit. Having the workday calendar and allocation calculation prepared before the audit begins is critical.
• Workers who visited New York offices during the grant-to-vest period and are near the 14-day threshold — the New York 14-day de minimis rule creates a binary outcome: 13 New York workdays means zero New York state income tax on the vest; 14 workdays means a formal New York non-resident allocation and Form IT-203 filing. Workers who know they are approaching the 14-day threshold should track exact New York workdays carefully and may choose to delay or reschedule a New York trip to keep the total below 14 during the grant period. At $5,000 in vest income per New York workday (a round number for illustration), the difference between 13 and 14 days is approximately $200–$600 in New York state income tax on the 1.8% New York fraction — a small amount, but the principle scales with vest income size.
• Multi-state workers who traveled extensively during the grant period — consultants, traveling sales representatives, and executives with regular multi-state travel face the most complex workday-fraction calculations because their California and New York workday fractions may be determined by hundreds of individual trip days across multiple states. For these workers, contemporaneous travel records — calendar entries, hotel receipts, flight records, and expense reports — are the audit documentation that supports the workday allocation. Reconstructed travel records created at tax time are routinely challenged by state auditors. Real-time tracking in a travel log or expense system creates the contemporaneous documentation that withstands audit.
• Employees switching equity platforms or companies who may have fragmented grant data — RSU grants from a prior employer that vested during a multi-state period require the same workday-fraction calculation as grants from the current employer. Equity platforms change (Morgan Stanley to Fidelity, E*Trade to Schwab) and companies are acquired — in both cases, historical grant records may be incomplete or transferred to a new platform without full documentation. Employees should download their complete grant history from every equity platform at each company in PDF and CSV format before any platform migration or company acquisition closes the access window. Missing grant date or original grant records can make the workday-fraction calculation impossible to document accurately, which is the worst position to be in during an audit.
• Remote workers who work for a California employer from outside California — this is a commonly misunderstood situation. A California employer does not create California-source income for an employee who has never physically worked in California during the grant-to-vest period. Physical location on each workday — not employer location — determines state sourcing. A Texas-based employee of a San Francisco company who works entirely in Texas, has never visited a California office, and holds RSUs from a California employer has zero California workdays and zero California-sourced RSU income. Conversely, a California resident who works remotely for a Texas employer has 100% California workdays and owes full California income tax on the RSU income.

Common RSU Multi-State Allocation Mistakes

Using calendar days of residency instead of workdays: Most states — and California's FTB Publication 1004 explicitly — calculate the allocation fraction using workdays, not calendar days of residency. A California resident who spent January 1 through June 30 in California (181 calendar days, approximately 130 workdays) and then moved to Texas for the second half of the year has approximately 130 California workdays in that year — not 181. Using calendar days systematically overstates the California fraction when the employee had significant PTO or holidays during the California period. Always use workdays — weekdays you actually worked — as the numerator and denominator.

Merging multiple grants into a single fraction: Each RSU grant has its own grant date, its own vest date, and its own independent allocation period. A grant issued in 2021 and a grant issued in 2023 that both vest in 2026 have completely different allocation periods and different California fractions. Blending them into a single average fraction produces incorrect results for both. Calculate each grant separately — this is how the FTB applies the rule during audits, and it is how your Form 540NR must report the income.

Assuming relocation eliminates all prior-state tax: Moving from California to Texas before vest day does not eliminate California's claim on the California-period fraction of vest income. The trailing California tax obligation exists for every grant that had California workdays in its grant-to-vest period. The only way to eliminate California's sourcing claim entirely on a specific grant is to have had zero California workdays during that grant's entire grant-to-vest period — which is only achievable by moving before the grant date or by a grant that postdates your California departure entirely.

Not filing Form 540NR when California-sourced RSU income exceeds the non-resident filing threshold: California non-residents who have California-sourced income must file Form 540NR if the income exceeds California's non-resident filing threshold. The threshold is the same as the resident threshold — single filers with more than $19,310 in California gross income for 2025 must file. California-sourced RSU income is California gross income for this threshold test. Non-residents who skip the 540NR because they no longer live in California, and whose W-2 Box 16 shows California wages they were unaware of, will receive a California FTB demand notice for the unfiled return.

Treating post-vest capital gains as California-sourced: The workday fraction determines California's share of the vest-date ordinary income. Appreciation in the RSU shares between the vest date and the sale date is a capital gain — and that gain is sourced to the state where you reside at the time of sale, not to California based on the grant-period workday fraction. A former California resident who vested shares at $100 and sold them at $150 six months later while living in Texas has California-sourced ordinary income of $100 per share (via workday fraction on the vest income) but zero California capital gains on the $50 per share appreciation — because they were a Texas resident at the time of sale.

Expert Insight and Market Impact

The multi-state RSU allocation issue has grown from a niche tax planning concern into a mainstream financial planning topic for the technology industry over the past decade — driven by the combination of large RSU grant values at major technology companies, significant technology employee migration from California to Texas, Florida, Nevada, and Washington during and after the pandemic remote work transition, and the FTB's increasingly sophisticated audit program for high-income non-residents with California-sourced equity income.

The FTB's data-matching program cross-references federal W-2 income reports, Form 1099-B stock sale reports, and California employer withholding records to identify non-residents who appear to have California-sourced RSU income that was not reported on a Form 540NR. The FTB receives California employer payroll data through their quarterly employer reporting system — which includes W-2 Box 16 California wages for all employees — and can identify individuals whose out-of-state addresses contrast with California wage reports. A California technology company that correctly reports California-allocated RSU wages in Box 16 of its employees' W-2s creates a direct data trail that the FTB uses to identify non-filers.

New York's Division of Taxation similarly audits large RSU vesting events for former New York residents and high-income non-residents with New York employer connections. The combination of high New York state tax rates (up to 10.9%), New York City income tax (up to 3.876%), and increasingly sophisticated NY audit targeting makes New York the second most significant multi-state RSU allocation risk after California for technology employees in the financial services industry.

Final Verdict

The workday fraction method is the governing principle for RSU multi-state income allocation in the US. The formula is simple: each state's share equals the workdays you physically worked in that state during the grant-to-vest period divided by total workdays in that period, multiplied by total vest income. The implementation is complex because every grant has its own separate calculation, workdays must be documented contemporaneously to withstand audit, California's trailing tax obligation follows you indefinitely after you leave the state, and New York's 14-day threshold creates a binary all-or-nothing outcome that requires careful trip-day tracking near the threshold.

For high-income technology employees, the dollar impact of the workday fraction calculation on a large RSU vest can be tens of thousands to hundreds of thousands of dollars in state income tax. Start a real-time travel log from your grant date. Calculate each grant's allocation separately. File Form 540NR for any year California-sourced RSU income is recognized. Apply the 14-day threshold check before any New York allocation calculation. And treat post-vest capital gains as separate — sourced to wherever you live at the time of sale, not tied to the grant-period workday fraction that governed the vest income.