Equity is earned over a period and taxed at a moment. When the earning period spans two countries, both may tax part of the same award — and because each applies its own timing rule, the two taxable moments may not even be the same day.
Who this guide is for
- Employees who moved country while holding options or restricted share units.
- Founders and executives with awards earned across more than one jurisdiction.
- Employers whose mobile population holds equity and whose payroll has to withhold on it.
Two questions: when, and where
The timing question is which event is taxable — grant, vest, exercise, or sale. Systems differ, and the difference is the source of most cross-border equity problems. One country may tax the spread at exercise as employment income while another taxes value at vest; a third may tax at grant in defined circumstances. Where the two countries pick different moments, relief mechanisms designed for the same-moment case work badly.
The sourcing question is how much of the award belongs to each country. The general approach is to look at the period the award was earned over — commonly grant to vest — and apportion by where the employee worked during it, usually by workdays. That means the answer depends on day records for a period that may have ended years before the taxable event.
How the instruments differ
Share options give a right to acquire shares at a price. Many systems tax the benefit at exercise, measured as the difference between market value and exercise price, as employment income, with any further movement to sale treated as a capital gain. Some systems have preferential regimes for qualifying plans that change both the timing and the character.
Restricted share units are a promise of shares, generally taxed as employment income when they vest and settle, on the value delivered. Because there is no exercise decision, the employee has less control over the timing and the tax often arises when shares are delivered rather than sold — which is why sell-to-cover arrangements exist.
Employee share purchase plans, phantom units and appreciation rights each behave differently again. The instrument's legal terms matter, and so does whether it is settled in shares or cash. Our pages on stock options across borders and restricted share units across borders cover the two main cases.
The withholding problem, and why it lands on the employer
The employer generally has to withhold on the employment income element, in each country that has a claim, at the moment that country treats as taxable. For a mobile employee that means the payroll has to know the person's work location history over the earning period, in a system that usually only knows where they are now.
This is where the practical failure happens. An employee exercises after moving; the new country's payroll withholds on the whole benefit; the former country also has a claim on the part earned there; and the employee has to unwind it through credits and refund claims across two systems. Building the allocation before the event, and telling both payrolls, is far cheaper.
What has to be known before a mobile employee's equity event:
- Grant date, vesting schedule and the date of each taxable event under each country's rules.
- Workdays by country over the earning period for each tranche.
- The country of residence at each taxable event, and any treaty position.
- Whether the plan qualifies for a preferential regime in either country.
- Which payroll will withhold what, and how the two will reconcile.
Relief, and where it falls short
Double taxation of the same award is relieved by foreign tax credits, and where the two countries disagree about allocation or timing, by the treaty. Credits work well when both countries tax the same income at the same time. They work poorly when the timing differs, because a credit generally requires the foreign tax to relate to income taxed in the same period — and a mismatch can strand the credit entirely.
Where relief genuinely fails, the treaty's mutual agreement procedure exists to resolve the allocation between the two authorities. It works, and it is slow, so its main practical value is as a reason to get the allocation right at the outset.
Departure, and the awards you take with you
Leaving a country while holding unvested awards raises two further questions. The departure country may treat emigration as a realisation event for some holdings, and awards may or may not be within that. And the award continues to vest under the plan while you are somewhere else, which is precisely what creates the split.
The planning options are mostly about timing and are mostly only available before the move: exercising vested options while still resident, allowing a tranche to vest before departure, or accepting the split with the allocation documented. Which is better depends on the two rate structures and on whether credits will actually be usable.
Handling a cross-border equity event
The work is done before the event. Afterwards it is a reclaim exercise.
- Build the award inventoryEvery grant with its type, grant date, vesting schedule, exercise price and current status, plus the plan documents.
- Establish the taxable moment in each countryGrant, vest, exercise or sale, under each country's own rules, and note where they differ because that is where relief will be hardest.
- Reconstruct workdays by countryFor the earning period of each tranche. This is the apportionment input, and it comes from travel and assignment records rather than from the payroll.
- Compute the allocation per trancheApportion the benefit between countries, and identify the withholding each payroll should apply at each event.
- Brief both payrolls before the eventSo withholding happens in the right proportions rather than being corrected by refund claim afterwards.
- File both returns with a matched positionThe same allocation on both sides, with credits claimed, and the mismatch flagged if the two timing rules differ.
What to gather
What an equity review needs:
- The plan documents and every grant agreement.
- A grant schedule with type, dates, quantities, exercise price and vesting terms.
- A record of exercises, vests, sales and cash settlements with dates and values.
- Workday records by country for each earning period.
- Residence dates and any departure or arrival return already filed.
- Payroll reports showing what has already been withheld and by whom.
- Broker statements for shares held after a taxable event, for cost base.
- Prior returns in both countries showing how earlier tranches were reported.
Where this goes wrong
Assuming the country you live in taxes the whole award
The part earned while working elsewhere generally belongs to that other country. Reporting the whole benefit in one place produces an over-payment in one country and an exposure in the other.
Not keeping workday records for the earning period
The apportionment needs where you worked between grant and vest, sometimes years before the taxable event. Without records the allocation is an assertion and the credit claim is fragile.
Exercising without checking the two timing rules
Where one country taxes at vest and another at exercise, a credit can be unusable because the taxes fall in different periods. Timing the event deliberately is often worth more than any election.
What to do next
If a move is planned and awards are outstanding, the pre-departure review is where the value is: what to exercise, what to let vest, and what allocation to document. If the event has happened, the work is establishing the correct allocation and recovering what was over-withheld.
We handle equity allocation, payroll briefing and both returns as one fixed-fee engagement agreed before work starts. See stock options across borders, exit strategy for founders and Canadians working in the US.
Read and approved for the 2025 and 2026 filing seasons by Udit Gupta, Cross-Border Tax Expert, Legal Quotient Consultants. Published as general information. For a position on your own file, call the 24-hour helpline.
This guide states mechanisms and names forms rather than quoting rates, thresholds or day counts, because those change annually and the guide does not. The current figure for your own tax year is confirmed against the authority that publishes it before anything is filed.
