Trailing Nexus: The Workday Allocation Rule for RSUs Vesting After a Move

A senior IC joined a Bay Area tech company in 2022 and received a 4-year vesting RSU grant. In 2024 they moved to Nevada. In 2025 and 2026, the remaining RSUs vest. California claims a share of that vest income based on how many workdays during the 2022-2026 grant period occurred in California.

This is trailing nexus: California’s right to tax income that was “earned” in California, even if it’s paid or vested after departure. The mechanism is workday allocation, and it applies to RSUs, option exercises, and most forms of equity compensation.

The math can be meaningful. A grant made 50% during California time might leave 50% of a $3M vest subject to California tax at 13.3% = $195K in unavoidable California tax, even after a complete move to a no-tax state.

The allocation formula

California applies the following formula under R&TC §17951 and FTB Publication 1031:

California-source income = Total vest income × (California workdays during grant-to-vest period / Total workdays during grant-to-vest period)

Workdays = days actually worked, not calendar days. Weekends, holidays, and vacation days are excluded from both numerator and denominator.

Grant-to-vest period = from the grant date to the vest date. For a 4-year grant with quarterly vesting, each vesting tranche has its own allocation based on the workdays from grant to that tranche’s vest.

Example calculation

Senior IC granted 10,000 RSUs on 1/1/2022 at a Bay Area company. Grant vests 25% per year on each anniversary. Moves to Nevada on 7/1/2024. At 1/1/2026 vesting (tranche 4), the stock is at $200 per share.

Tranche 4 vest on 1/1/2026:

• Grant-to-vest period: 1/1/2022 to 1/1/2026 = 4 years
• Workdays in California (assume 250 workdays/year, 2.5 years in CA): 625
• Total workdays over 4 years: 1,000
• California allocation: 625/1000 = 62.5%

Tranche 4 vest income: 2,500 shares × $200 = $500,000 California-source: $500K × 62.5% = $312,500 California tax (at 13.3% top rate): $41,562

Across all four tranches, the California tax bill on the moved-residence portion could easily reach $100K-$200K if total grant value is $2M-$3M.

Remote work complications

If you worked remotely from Nevada while still employed by the California company, those days count as non-California workdays, if properly documented. FTB auditors can challenge:

• Did you actually work those days (timesheets, meeting records)?
• Was the work primarily in Nevada or did you take California business trips?
• Did the employer report any California days in their records?

Some employers don’t track workday location beyond “employed in San Francisco office.” Employees who moved remotely and expected trailing nexus to be favorable found the employer reporting 100% California workdays because HR systems defaulted to the hire state.

Documentation tip: keep a personal workday log with location, track business-trip travel separately, and compare against the employer’s Form W-2 and equity statements. Discrepancies should be resolved before filing.

Double-trigger RSU timing

For pre-IPO companies with double-trigger RSUs (time-based + liquidity), the “vest” for tax purposes is typically the second trigger (liquidity). Some practitioners argue the allocation period is grant-to-liquidity, others argue grant-to-time-based-vest.

The FTB’s position is typically to use grant-to-liquidity-event for the full allocation period. This means RSUs that “time-vested” years before IPO but had no tax impact until IPO count all the way through the IPO for workday allocation.

For pre-IPO employees who moved before IPO, this matters. Every month of California residency during the grant period adds to the California numerator.

Option exercises

For stock options (ISO or NSO), the allocation period is grant date to exercise date. Non-qualified option (NSO) spread is ordinary income at exercise, sourced by workdays.

For ISOs, the qualifying disposition gain (if held long enough) is generally capital gain sourced to residence at sale, not workdays. The AMT adjustment at exercise is sourced by workdays.

What’s sourced to residence state

California trailing-nexus claims apply to ordinary income with California work connection. Capital gains on sale of already-vested stock are generally sourced to the state of residence at sale.

Example: RSUs vested in 2024 while in Nevada (or earlier in California), stock held until 2027, sold while resident of Nevada. The capital gain on sale (from vest price to sale price) is Nevada-source, not California. California has no claim on post-residence capital appreciation.

For departing taxpayers, the strategy is to separate vest-income (workday-allocated) from post-vest capital gains (residence-allocated) by timing sales after establishing new residency.

The “multiple state” wrinkle

If you moved from California to New York to Nevada during a grant’s vesting period, each state claims its share. The workdays during New York residence are New York-source. The allocation becomes three-way.

For multi-state tax resolution:

• Each state gets its workday share of ordinary income
• Credits for tax paid to other states apply where available
• Final residence state’s rules determine capital gains on later sales

Working across multiple states during a vesting period adds complexity and often audit risk as each state asserts its share.

Planning before the move

Best practices for departing taxpayers with California equity:

1. Accelerate vest before the move if possible (earlier tranches have less California time in grant period)
2. Exercise vested options before the move to lock in workday allocation at current state
3. Time the move to start with a new tax year if possible
4. Document workdays carefully from day one of the new residence
5. Plan capital gains on already-vested stock to happen after clean residency change
6. Keep records for at least 8 years (California’s assessment period can extend)

Frequently asked

What counts as a “workday” exactly? Days on which services were performed for the employer. Employees generally work 240-260 workdays per year. Weekends, holidays, PTO, and sick days are excluded.

How does California know about my workdays? Primarily from the employer’s W-2 reporting and the FTB’s own audit procedures. During an audit, the FTB can subpoena employer records, calendar entries, and travel data.

Does the §6501 statute apply to trailing nexus claims? California’s R&TC §19057 assessment period is generally 4 years from filing. For substantial understatement, it can extend to 6 years. The federal §6501 3-year period applies only to IRS audits.

What if my employer reported zero California workdays after I moved? Then you use the employer’s reporting on your state return. If the FTB disagrees, they’ll audit. Be prepared to substantiate with independent records.

Does moving to another high-tax state help? Moving from California to New York doesn’t avoid state tax, New York taxes residents on the post-move portion and California still claims trailing nexus on the pre-move portion. Total state tax may be similar or higher depending on rates. Moving to Nevada, Texas, Florida, or Wyoming provides clean non-tax state for the post-move allocation.