Stock Options and RSUs When Moving Countries: Cross-Border Tax Guide

In This Guide

Start with the award file, not a residency headline
Build an event timeline before calculating tax
Source the income to the service that earned it
Put treaty and payroll analysis on separate tracks
Model mismatches with one reconciled example
Treat moves, remote work and transactions as fact changes
Lock down basis, currencies and the evidence file
Frequently Asked Questions
Sources Used in This Guide

Cross-border equity tax is an allocation problem before it is a rate problem. A useful analysis connects each award to the work that earned it, identifies what each country taxes and when, then reconciles payroll, treaty relief and the later share sale. A change of residence matters, but it rarely answers the whole question.

This guide is a framework for founders, executives, employees, advisers, payroll teams and mobility teams. It is not a country opinion. Domestic law, the exact treaty text and the award documents must be checked for every country involved. The analysis below is current through 23 July 2026.

There is no universal grant-to-vest formula, no global definition of a workday and no worldwide rule that an RSU is taxed at vest or an option at exercise. Those are common outcomes in some systems, not international law.

Start with the award file, not a residency headline

Begin by naming the instrument under each relevant country's law. A plan may call an award an RSU, option, restricted share, stock appreciation right or cash-settled unit. The label does not decide its tax treatment. Ask what the employee has at grant, what conditions must be met, whether shares or cash will be delivered, and whether the employee pays anything. Obtain the plan, grant notice, vesting schedule, amendments, transaction documents and broker statements.

Then separate four kinds of authority. Mixing them is a common source of confident but wrong advice.

Authority	What it answers	How to use it
Domestic tax law	Taxable event, amount, character, deductions, basis and filing duties	Start here for every country that claims residence or source taxation.
Treaty text and protocol	Which state may tax, residence tie-breakers, employment article limits and double-tax relief	Read the treaty actually in force. Model conventions and summaries are not substitutes.
Tax-authority guidance	Administration, examples, forms and the authority's interpretation	Useful evidence, but check whether it is binding, current and limited to stated facts.
Practical inference	How payroll, mobility, legal and the employee should coordinate	Label it as process advice, not law.

The distinction also prevents one country's vocabulary from spreading. ISO and NSO are U.S. federal tax classifications. Other countries have their own approved, qualified or tax-favoured plans, often with different conditions. The IRS stock-option summary explains U.S. statutory and nonstatutory options; it does not create a global taxonomy.

Build an event timeline before calculating tax

One award can cross several tax years and countries. Plot the legal and economic events first. Add residence status, treaty residence, physical work location and employing entity for every segment. Do this by vesting tranche, because each tranche may have a different earning period.

A complete timeline keeps the compensation event separate from the later investment return.

Event	Question to resolve	Cross-border consequence
Grant	Was property transferred, or only a conditional promise or right?	May start an earning period; it is not always a taxable event.
Vesting	Which service, performance or liquidity conditions lapse?	May end the earning period, trigger income, or do neither.
Exercise	When is an option used and what is the spread?	Often a compensation event for ordinary options, but local exceptions can move or defer tax.
Settlement	When are shares or cash actually delivered?	Can differ from vesting; valuation and withholding may follow settlement.
Sale	What shares were sold, for how much, and with what basis?	Usually starts a separate capital-gain calculation after compensation income.
Forfeiture or expiry	Was the award cancelled, returned or allowed to lapse?	Unvested value may never be taxed, but a prior charge, paid option price or deduction may require a refund or loss claim.

Do not collapse vesting and settlement without reading the documents. In its U.S. guidance for nonresident recipients, the IRS distinguishes an RSU grant, vesting date and transfer date, and explains that the transfer date fixes the property and fair market value for its section 83 analysis. That is useful as a U.S.-specific example, not a rule for other systems.

Source the income to the service that earned it

Once domestic law identifies compensation income and its amount, determine which work earned it. A common analysis apportions income over an earning period using service or workdays. HMRC guidance says UK option gains generally follow service from grant to vest by workdays, while warning that a treaty can specify otherwise. Finland's tax authority similarly starts with grant to full vest, or earlier employment termination, and links the taxable share to wages taxable during that period. Both authorities also recognise that the facts may point to a different earning period. See the HMRC treaty interaction guidance and Finnish cross-border option guidance.

The matrix is an audit trail: earning period, physical work location, employer and treaty treatment by day or accepted reporting unit.

Matrix row	Common starting point	What can change it
Earning period	Grant to vest for a service-conditioned tranche	Past-service award, performance period, retirement eligibility, continued vesting, termination, acceleration or treaty wording
Numerator	Qualifying service days physically worked in the country	Local source law, treaty definition, director rules, leased employment and multi-state rules
Denominator	Total qualifying service days everywhere in the same period	Whether holidays, leave, weekends, travel or non-service days are included
Residence overlay	Residence country may tax worldwide income	Split-year rules, dual residence, treaty tie-breaker and remittance or exemption regimes
Remote work	Day follows the place services are physically performed	Specific treaty rules, frontier-worker rules, exceptional agreements and local deeming provisions
Post-vest days	Often outside a grant-to-vest allocation	A treaty or domestic rule may use grant-to-exercise or another period

That matrix is why no universal workday formula exists. Even where two countries use a time fraction, they may disagree about its dates and denominator. The IRS, for example, generally describes U.S. source employee compensation for a nonresident as U.S. service days over worldwide service days during the vesting period, but it notes that the U.S.-UK treaty can use grant to exercise for an option. The applicable treaty text controls.

Put treaty and payroll analysis on separate tracks

Most employment articles begin with a residence-state right to tax and allow the work state to tax remuneration for employment exercised there. A short-stay exception may preserve exclusive residence-state taxation only if every stated condition is met, commonly a day limit plus employer and permanent-establishment tests. Never rely on a generic "183-day rule." Check the measurement period, employer concept, economic-employer interpretation and whether a protocol addresses stock awards.

A treaty limits tax; it does not necessarily switch off payroll. Relief may require a certificate, advance waiver, return disclosure or refund claim. Nor does an income-tax treaty automatically decide social insurance. The IRS treaty overview makes the narrower point for U.S. treaties: benefits vary by country and income item, residence is treaty-specific, and some U.S. states do not follow federal treaties.

Legal liability, payroll collection and final relief are connected, but they are not the same calculation.

For each taxable event, payroll should answer: which entity is the payer; which country requires registration; whether withholding applies to cashless income; whether sell-to-cover is available; what wage and social-insurance base applies; and which information return is due. A shadow payroll is a practical mechanism that records host-country pay and deductions while cash may remain on home payroll. It does not itself create or remove a tax obligation.

Official rules show why payroll cannot assume consistency. Canada requires employers to calculate, withhold and report specified security-option benefits under its own categories; see the CRA security-option payroll guidance. UK rules have separate employment-related securities returns, covered in HMRC's reporting notes. A company may therefore need home payroll, host shadow payroll and plan-administrator reporting for one vest.

Model mismatches with one reconciled example

The following numbers are hypothetical. They illustrate a workflow, not the law of Countries A, B or C.

An employee receives 1,200 share-settled RSUs on 1 January of Year 1. One tranche vests and settles on 31 December of Year 3. The award requires continuous service. During the assumed earning period, the employee has 660 accepted service days: 360 physically in Country A, 240 in Country B after moving there, and 60 working remotely in Country C. Fair market value at settlement is €50 per share.

Step	Hypothetical calculation	Result
Compensation amount	1,200 × €50	€60,000
Country A service share	€60,000 × 360 ÷ 660	€32,727
Country B service share	€60,000 × 240 ÷ 660	€21,818
Country C service share	€60,000 × 60 ÷ 660	€5,455
Later sale	1,200 × €58 less assumed €60,000 basis	€9,600 gain before costs

Do not file those allocations until each country confirms the earning period, workday convention and taxing right. Country B might tax all €60,000 because the employee is resident at settlement, while still giving credit or exemption for tax properly imposed by A and C. Country A might tax its sourced part a year later, at exercise for an option rather than settlement for an RSU. Country C may apply a short-stay treaty exemption, or it may require payroll withholding despite a later refund.

A reconciliation should show gross income, source share, tax withheld, final tax, relief claimed and unresolved excess by country and year.

Timing and character mismatches need their own schedule. One country may call the €60,000 employment income at settlement; another may tax an option spread at exercise; a third may characterise part of the return as capital gain. A residence country may credit only qualifying foreign income tax on the same income, subject to baskets, limits and timing rules. The IRS foreign-tax-credit guidance, for example, warns that creditable tax is not necessarily the amount withheld and that treaty-reduced excess may need to be refunded by the foreign country.

Practical inference: pursue the source-country refund before treating excess withholding as creditable. Track amended returns, carryovers, competent-authority options and limitation periods. A tax payment in both countries does not prove that both assessments are treaty-correct.

Treat moves, remote work and transactions as fact changes

For a departure or arrival year, prepare a day-by-day residence and work calendar. Mark domestic residence start and end dates, treaty residence, split-year eligibility, immigration status, employer changes and permanent-establishment exposure. HMRC's current Overseas Workday Relief guidance illustrates how a split year and workday apportionment can affect securities income. It is a UK rule, not a portable formula.

Remote work changes the service location even if payroll, manager and employing company stay put. Log where the person worked, not where the laptop or payroll was based. Revisit the treaty's short-stay test and employer conditions. Mobility should notify payroll and the plan administrator before a vest or exercise so withholding does not rely on an obsolete address.

A corporate transaction can rewrite the timeline. Review whether awards accelerate, are assumed, substituted, cashed out, rolled into buyer equity or cancelled. Identify the service period attached to the replacement award and whether old and new awards must be analysed separately. A change-in-control cashout can combine vesting, settlement and disposal on one date while several payrolls race to report it. That operational compression does not merge the legal questions.

Forfeiture needs equal attention. If an unvested promise disappears before any taxable transfer, there may be no income. If tax was charged earlier, shares are clawed back, or the employee paid for an option that expires, local law decides whether a deduction, loss, amended return or no relief follows. Do not net a forfeiture against another award without authority.

U.S. citizens and green-card holders: separate caveat. Moving abroad does not normally end U.S. worldwide taxation for a citizen or resident alien. The IRS guidance for U.S. persons abroad confirms worldwide reporting and points to the foreign earned income exclusion and foreign tax credit. Treaty saving clauses, state residence, green-card termination and expatriation rules can alter the result. This is an extra U.S. layer, not the baseline for everyone else.

Lock down basis, currencies and the evidence file

After compensation tax, start a share lot ledger. Record shares delivered, shares withheld or sold for payroll, acquisition date, amount paid, compensation included in income, any exempt compensation that local law still adds to basis, fees and later sale proceeds. Basis mistakes create a second tax on value already taxed as pay. Finland's official guidance offers one jurisdiction-specific example: for shares bought under an option, acquisition cost includes the share and option price plus the amount taxed as wages. See the Finnish option guidance. Confirm the rule independently in every filing country.

Run currencies event by event. Preserve the share price, quote source, timestamp, exchange rate and filing currency for grant if relevant, vest, exercise, settlement and sale. Do not translate the final euro gain once and assume every country agrees. The IRS currency guidance, for example, generally calls for the prevailing rate when an item is received, paid or accrued. Another country may prescribe a daily official rate, an annual average in limited cases, or a different valuation moment.

The evidence file should let another adviser reproduce every source fraction, valuation, withholding entry and basis adjustment.

Before a move, complete this checklist:

Inventory every award and tranche, including underwater, unvested, performance and cash-settled awards.
Download plan documents, grant notices, transaction history and current cap-table or broker records.
Build the workday calendar from grant through expected vest, with travel, leave and remote-work locations.
Ask advisers in both countries for the domestic event, earning period, source method, treaty article, relief route and filing deadline.
Ask payroll who will withhold, whether shadow payroll is required, what happens if there is no cash wage, and which employer reports the event.
Model exercise, vest, settlement and sale dates under several share prices and exchange rates; include cash needed for tax.
Preserve prior returns, assessments, tax certificates, payslips, W-2/T4 or local equivalents, withholding receipts, refund claims and treaty disclosures.

Retain the file at least through the longest assessment, refund and basis substantiation period that could apply. The award can outlive an assignment, and the shares can outlive the award.

Frequently Asked Questions

Does moving country make an equity award taxable immediately?

Not necessarily. Some countries have departure charges or special residency rules, but many tax the award only at a later vesting, exercise, settlement or sale event. The move still changes residence, source allocation, payroll and treaty facts, so run the analysis before departure.

Is grant-to-vest always the correct workday period?

No. It is a common starting point for service-conditioned awards in several official systems, but plan facts, domestic law and treaty text can require grant-to-exercise, a performance period, past service or an earlier end at termination. Denominator rules also differ.

Can a treaty stop payroll withholding?

Sometimes, but often only after a form, certificate or advance waiver. Payroll may have to withhold first even where the final treaty result is exemption or a smaller source allocation. The employee may need a return or refund claim.

What if two countries tax the award in different years or as different types of income?

Prepare a country-by-country reconciliation of event date, character, source amount, tax paid and relief claimed. Credits may be limited or unavailable in the first year. Refunds, amended returns, carryovers or competent-authority relief may be needed.

Does selling the shares create a second tax event?

Usually yes. Compensation income generally establishes or increases basis, and the later price movement is tested under capital-gain rules. Track each lot and each country's basis rule so the compensation amount is not taxed twice.