Stock Options When You Relocate Between Canada and the US: Who Taxes What

An employee who relocates between Canada and the US while holding unvested stock options faces one of the more complex cross-border tax problems. Both countries want to tax the gain on exercise, and both have a reasonable claim: the options were granted as compensation for services, and the employee performed services in both countries during the vesting period. The treaty allocates the gain based on where the employment was exercised, but the mechanics of making that allocation work on two separate tax returns, with two different timing rules, requires careful planning.

How are stock options taxed in the US?

US tax treatment depends on whether the option is an incentive stock option (ISO) under IRC 422 or a nonqualified stock option (NQSO).

NQSOs: The spread between the exercise price and the fair market value at exercise is ordinary compensation income, reported on the employee’s W-2 and subject to income tax, Social Security tax (up to the wage base), and Medicare tax. The employer takes a corresponding deduction under IRC 83(h). The employee’s basis in the shares is the FMV at exercise, and any subsequent gain or loss on sale is capital gain or loss.

ISOs: No regular income tax at exercise. The spread at exercise is an adjustment for Alternative Minimum Tax (AMT) purposes under IRC 56(b)(3). If the employee holds the shares for at least two years from the grant date and one year from the exercise date (the “qualifying disposition” holding period), the entire gain on sale is long-term capital gain. If the employee sells earlier (a “disqualifying disposition”), the spread at exercise becomes ordinary income retroactively.

ISOs have a significant limitation for cross-border situations: they can only be granted to employees of the issuing corporation or its US subsidiaries. An employee who transfers to a Canadian subsidiary may lose ISO eligibility, and the options may convert to NQSOs.

How are stock options taxed in Canada?

Canada taxes stock option benefits under ITA 7. The taxable benefit arises at the time the option is exercised (not at vesting, not at grant). The benefit is the spread between the exercise price and the FMV at exercise, and it is included in employment income.

The 50% stock option deduction under ITA 110(1)(d) reduces the effective tax rate to roughly the capital gains rate if certain conditions are met: the exercise price was not less than the FMV at grant, the shares are prescribed shares (generally common shares of a CCPC or shares listed on a designated stock exchange), and the employee dealt at arm’s length with the employer. For Canadian-controlled private corporations (CCPCs), the taxable event is deferred until the shares are disposed of (not at exercise), and the 50% deduction applies without the FMV-at-grant condition as long as the shares are held for at least two years.

For non-CCPC employers (including US public companies), budget changes effective for options granted after June 2024 limit the 50% deduction to the first $200,000 of option grants that vest in a year (based on the FMV of the underlying shares at the grant date). Options above this threshold are taxed at the full inclusion rate.

How is the gain allocated between countries on relocation?

The standard allocation method, consistent with both the CRA’s administrative position and the IRS’s approach, divides the option gain based on the proportion of the vesting period spent in each country.

The vesting period typically runs from the grant date to the vesting date (or the exercise date, if the option is exercised before full vesting). Days worked in each country during this period determine each country’s share.

The formula:

• US share = (Days worked in the US during the vesting period / Total days in the vesting period) x Total option gain
• Canada share = (Days worked in Canada during the vesting period / Total days in the vesting period) x Total option gain

What happens to ISO status on relocation?

ISOs are strictly a US concept. Canada does not have an equivalent “incentive stock option” category. When an employee with ISOs relocates to Canada, several problems arise:

Employment transfer: If the employee transfers from the US entity to a Canadian subsidiary, the ISO may lose its qualified status because ISOs must be held by an employee of the granting corporation or its parent/subsidiary chain. Whether the Canadian entity qualifies depends on the corporate structure.

Exercise from Canada: An employee who exercises ISOs while residing in Canada gets no US regular income tax at exercise (the ISO deferral still applies for US tax purposes), but Canada taxes the employment benefit at exercise under ITA 7. The AMT adjustment still applies on the US side. The employee may owe AMT in the US and regular tax in Canada on the same gain, with the foreign tax credit providing only partial relief because the AMT rate and the Canadian rate apply to different bases.

Disqualifying disposition: If the employee sells the shares before meeting the ISO holding period, the spread becomes US ordinary income retroactively. The US taxes the gain as compensation, and Canada has already taxed its allocated share as an employment benefit. The foreign tax credit should prevent full double taxation, but the calculations are complex.

The practical advice for employees relocating with ISOs: exercise before relocating if possible, and if the ISO holding period is close to completion, consider holding through the qualifying disposition before moving. Once the employee is in Canada, the ISO’s US tax advantages are diluted by Canada’s parallel taxation.

How do you prevent double taxation?

The treaty (Article XV for employment income, Article XXIV for the elimination of double taxation) provides the framework. Each country taxes only its allocated share of the option gain, and the residence country gives a credit for tax paid to the source country.

For an employee who relocated from the US to Canada and exercises options while in Canada:

1. File a Canadian T1 reporting the full option gain as worldwide income (Canada taxes residents on worldwide income).
2. File a US Form 1040-NR reporting only the US-allocated share as US-source compensation.
3. Claim a foreign tax credit on the Canadian return (Form T2209) for the US tax paid on the US-source portion.

For an employee who relocated from Canada to the US and exercises options while in the US:

1. File a US Form 1040 reporting the full option gain as worldwide income.
2. File a Canadian T1 (or no Canadian return if the employee has no other Canadian-source income, though the CRA may assess a departure tax under ITA 128.1 on emigration, which can capture accrued option gains).
3. Claim a foreign tax credit on the US return (Form 1116) for any Canadian tax paid on the Canadian-source portion.

The departure tax trap: When a Canadian resident emigrates, ITA 128.1 deems a disposition of most property at FMV on the departure date. For stock options, the CRA’s position is that unvested options are not subject to the departure tax (they are not “property” for this purpose), but vested, unexercised options may be. If the departure tax applies to vested options, Canada taxes the accrued gain up to the departure date, and the employee must track this amount to avoid double taxation when the options are eventually exercised in the US.

What are the common mistakes?

• Not allocating the gain. Some employees report the full option gain in the country where they exercised, ignoring the vesting-period allocation. This overreports income in one country and underreports in the other.

• Using the wrong vesting period. The allocation uses the period from grant to vest, not grant to exercise. Options that vested entirely in one country are 100% sourced to that country, even if exercised years later in the other country.

• Forgetting the AMT for ISOs. A US person who exercised ISOs and then moved to Canada still has the AMT adjustment on the US return. If the shares are sold while in Canada, the AMT credit from prior years may be recoverable, but only if the employee continues to file US returns (which they must, as they will have US-source income from the option allocation).

• Missing the 50% deduction in Canada. The Canadian 50% stock option deduction requires that the exercise price be at least equal to the FMV at grant. For options granted by a US employer before the employee moved to Canada, the FMV-at-grant test uses the US stock price in USD, and the exercise price is also in USD. Currency fluctuations do not affect the test (the comparison is made in the currency of the option), but the employee or their advisor must verify that the condition is met using the grant-date FMV, not the exercise-date FMV.

• Not filing Form 8833. When claiming treaty-based allocation on the US return, Form 8833 should be filed to disclose the treaty position. The penalty for non-disclosure under IRC 6712 is $1,000 per failure.

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.