Cross-Border Stock Options and Equity Compensation: Workday Sourcing, the Canadian Deduction, the U.S. ISO, and the Employee Who Moves

Equity compensation is earned over time, and when the employee moves countries during that time, both countries want their share. The taxable event in each country: Canada taxes a stock option benefit when the option is exercised (the spread — fair market value at exercise less the exercise price — is employment income; for a Canadian-controlled private corporation's options granted to an arm's-length employee, the inclusion is deferred until the shares are sold under subsection 7(1.1), with the 50 percent deduction under paragraph 110(1)(d.1) if the shares are held two years), with the stock option deduction of 50 percent of the benefit if the conditions are met (exercise price at least the fair market value at grant, prescribed shares, arm's length — paragraph 110(1)(d); and, for options granted after June 30, 2021 by employers other than CCPCs with annual gross revenue over C$500 million, only options on up to C$200,000 of shares — valued at grant — vesting in a year qualify), making the effective rate about half the employment rate; restricted stock units are taxed at vesting (when the shares or cash are received) as employment income without the deduction (an RSU has no exercise price, so it can't meet the grant-date fair-market-value condition). The United States taxes a nonqualified stock option at exercise on the spread as wages; an incentive stock option (ISO) is not taxed at exercise for regular tax (only the alternative minimum tax adjustment) and its gain at sale is a capital gain if the holding periods are met (two years from grant, one year from exercise); restricted stock units are wages at vesting; restricted stock (actual shares subject to vesting) is taxed at vesting unless an 83(b) election is made within 30 days of the grant. The sourcing — workdays: a benefit earned partly in each country is sourced by time spent in each — for stock options the treaty sets the rule itself (paragraph 6 of Annex B to the 2007 Fifth Protocol, applying Articles XV and XXIV): the benefit is attributed to each country in proportion to the days from grant to exercise (or disposal) on which the employee's principal place of employment for the employer group was in that country, out of all days employed in that period — grant to exercise, not the OECD's grant-to-vesting period; RSUs have no special treaty rule and are generally sourced by workdays over the grant-to-vesting period; so an option granted in Toronto and exercised four years later, with the employee based in Toronto for two years and Miami for two, is half Canadian-source and half U.S.-source. The tax in each country — and the credit: Canada taxes a resident on worldwide income — an employee who exercises while a Canadian resident is taxed in Canada on the whole benefit, with a foreign tax credit for the U.S. tax on the U.S.-source portion; a non-resident of Canada at exercise is taxed in Canada only on the Canadian-source portion (the Canadian days — taxed under subparagraph 115(1)(a)(i) as income from duties performed in Canada, with the stock option deduction allowed against it under paragraph 115(1)(d) if the conditions are met); the United States taxes a U.S. resident (or citizen) on worldwide income — an employee who exercises after moving to Miami is taxed in the United States on the whole benefit, with a foreign tax credit for the Canadian tax on the Canadian-source portion; the treaty's sourcing rule and the residence country's credit are designed to avoid double tax, but the mismatches — the Canadian 50 percent deduction (reducing the Canadian tax, so the U.S. credit for it is smaller), the ISO's deferral (no U.S. tax at exercise, while Canada taxes the Canadian portion then — a timing mismatch where the Canadian tax may be paid years before the U.S. tax it would offset — excess U.S. foreign tax credits carry back one year and forward ten under section 904(c), while Canada's foreign tax credit on non-business income has no carryover), and the currency — leave residual tax. The employee moving from Canada to Florida: before the move, the departure tax deems a disposition of the employee's property — but unexercised options and unvested RSUs are not property subject to the departure tax (rights under an employee stock option agreement, including share-settled RSUs, are "excluded rights or interests" under subsection 128.1(10), and both are taxed as employment income when exercised or vested); after the move, the exercise or vesting is taxed in Canada on the Canadian-source portion (the Canadian workdays), with Canadian withholding by the employer (or the Canadian payroll of the former employer — under subsection 7(4) the benefit is still received by virtue of the employment, and the employer withholds under subsection 153(1) and Regulation 102 on the Canadian-source portion and reports it on a T4), and in the United States on the whole benefit with the credit; the RRSP and the departure planning (the NR73 guide) run alongside. The employee moving from the United States to Canada: the same in reverse — the U.S.-source portion (U.S. workdays) stays taxable in the United States after the move (a nonresident's U.S.-source wages), and Canada taxes the whole benefit once the employee is a resident, with the credit; a U.S. citizen who moves stays taxable in the United States on the whole benefit (the saving clause — the treaty guide) and claims the credit for Canadian tax on the Canadian-source portion. The employer's withholding: each country's payroll withholding follows its sourcing — the Canadian employer withholds Canadian tax on the Canadian-source portion (even after the employee has left — the former employer's or the group's Canadian payroll), and the U.S. employer withholds U.S. tax on the benefit for a U.S. resident (or the U.S.-source portion for a nonresident); a group with entities in both countries recharges the equity cost between them (a transfer pricing point — the entity employing the employee during each period bears that period's share — and Canada's separate rules on when the employer can deduct its equity cost), and the payroll teams in both countries need the employee's workday history. The bookkeeping: the grant agreements and vesting schedules; the employee's workday log by country across the vesting period; each exercise or vesting event's benefit and sourcing; withholding in each country; the credits on each return; the Canadian stock option deduction eligibility; the ISO holding periods. The errors: the whole benefit taxed by both countries with no sourcing (the employer's two payrolls each withholding on 100 percent); the workday history never recorded (sourcing reconstructed from memory); the Canadian stock option deduction missed on a non-resident's Canadian-source portion; an ISO's AMT adjustment ignored; and the employee's departure planned without the unvested equity in view.

Key takeaways

• Canada taxes options at exercise (with a 50 percent deduction if eligible) and RSUs at vesting; the United States taxes nonqualified options at exercise, ISOs at sale (with AMT at exercise), and RSUs at vesting.
• A benefit earned partly in each country is sourced by days in each country — for options, the treaty counts days of principal employment between grant and exercise; RSUs are generally sourced by workdays between grant and vesting.
• The residence country taxes the whole benefit with a credit for the other country's tax on its portion; the non-residence country taxes only its workday share.
• Mismatches leave residual tax: Canada's deduction shrinks the creditable tax, an ISO's U.S. deferral splits the timing, and currency moves the numbers.
• Unexercised options and unvested RSUs aren't caught by the Canadian departure tax — they're employment income when exercised or vested, sourced by workdays.
• Both employers' payrolls withhold on their own country's share — which requires the employee's workday history.

The cross-border equity compensation file

Grant agreements; vesting schedules. Workday log by country across each vesting period. Each event: benefit, sourcing, withholding in each country. Canadian stock option deduction eligibility; ISO holding periods and AMT. Credits on both returns; currency. Intercompany recharge of the equity cost. The workday log is the document both countries' sourcing depends on.

Worked example

A Toronto software engineer at a Canadian public company holds options granted in 2022 vesting over four years; she moves to Miami on January 1, 2025 to work for the company's U.S. subsidiary. In 2026 she exercises 10,000 options with a US$400,000 spread. Sourcing: of the days from grant (mid-2022) to exercise, her principal place of employment was in Canada for 55 percent (2022–2024) and in the United States for 45 percent (2025–2026). Canada: as a non-resident, she's taxed on the Canadian-source 55 percent — US$220,000 — as employment income from duties performed in Canada, with the 50 percent stock option deduction (the options qualified — the shares vesting each year were worth less than C$200,000 at grant, inside the annual vesting limit that applies to her large non-CCPC employer), withheld through the Canadian parent's payroll. United States: as a U.S. resident, she's taxed on the whole US$400,000 as wages (nonqualified options), withheld through the U.S. subsidiary's payroll, with a foreign tax credit for the Canadian tax on the Canadian portion — the Canadian tax, halved by the deduction, offsets only part of the U.S. tax on that portion, leaving residual U.S. tax she had budgeted. Her colleague, whose two payrolls each withheld on 100 percent of his RSU vesting, spent a year recovering the double withholding through both countries' returns.

Official sources

Publication 597 explains: “This publication provides information on the income tax treaty between the United States and Canada. It discusses a number of treaty provisions that most often apply to U.S. citizens or residents who may be liable for Canadian tax.” — Internal Revenue Service, Publication 597 (10/2015), Information on the United States–Canada Income Tax Treaty, https://www.irs.gov/publications/p597

The CRA states: “You have to fill out an NR4 slip for every non-resident to whom you paid or credited amounts described under Part XIII of the Income Tax Act (ITA), even if you are not required to deduct any tax.” — Canada Revenue Agency, When to complete an NR4 slip, https://www.canada.ca/en/revenue-agency/services/tax/international-non-residents/payments-non-residents/nr4-part-xiii-tax/nr4/nr4-slip/when-complete-nr4-slip.html

Practitioner note

Equity compensation earned partly in Canada and partly in Florida is taxed by both countries, each on its share of the days between grant and exercise (for options) or vesting (for RSUs) — with the residence country taxing the whole benefit and crediting the other's tax, and Canada's 50 percent stock option deduction and the U.S. incentive stock option rules making the credit imperfect. Our desks build the employee's workday history before the first exercise, source each event, coordinate both employers' withholding so neither payroll takes 100 percent, and plan the move with the unvested equity in view — because the departure tax doesn't reach it, but both countries' payrolls will.

See also: For related guidance, see stock options and RSUs when moving from Canada to the U.S. and what triggers the Canadian departure tax; and browse every cross-border tax topic guide, organized by situation.

Next step

Fairlight Accounting is a cross-border accounting and tax practice with a U.S. Tax Desk and a Canadian Tax Desk. Our U.S. Tax Desk and Canadian Tax Desk handle cross-border equity compensation — stock option, RSU, and ISO taxation in both countries, treaty workday sourcing, Canadian stock option deduction analysis, employer withholding coordination across two payrolls, foreign tax credit planning, intercompany recharges, and pre-move equity reviews. See pricing or book a call.