RSUs in Spain. In Spain an RSU is not a legal category: it is a contractual promise to which rules written for something else are applied. The characterisation comes out of your plan document, not out of the name of the instrument, and that is where two colleagues with the same grant end up with two different returns.
The acronyms are theirs, and the tax is paid here
ISO and NSO are categories of United States tax law. For a US taxpayer, an incentive stock option carries favourable treatment: no ordinary income on exercise and, if the holding periods are respected, the benefit can be taxed as a long-term capital gain, subject to the alternative minimum tax overlay. A non-qualified stock option is everything else: the spread on exercise is ordinary income, withheld through payroll.
That favourable regime is a construction of theirs, designed for people taxed there. It does not travel. If you are tax resident in Spain, Spanish income tax does not recognise the category, there is no rule importing it and there is no parallel regime of qualified options in our law. The label on the plan, by itself, does not change your Spanish bill.
What each acronym means in each place
| ISO | NSO | |
|---|---|---|
| What it is there | A qualified option, with favourable treatment if the periods and conditions are met | An ordinary option, employment income on exercise |
| Who can receive them there | Employees, within the plan's limits and conditions | Anyone: employees, directors, advisers, contractors |
| What it is here | An option over shares, nothing more | An option over shares, nothing more |
| Spanish income tax treatment | Employment income in kind on exercise and a capital gain on sale | Identical |
| What does change the Spanish result | The contract clauses: when it vests, when it can be exercised, what happens when you leave, who grants it | |
So does the distinction not matter?
It does not matter as a label and it matters a great deal as a symptom. That a plan is an ISO plan tells you it was designed by and for a US structure, and that brings very concrete consequences you do feel here:
- The post-termination exercise window. ISO plans usually impose a short period from leaving in which to exercise, because otherwise the option stops being qualified over there. That period, imported verbatim into your contract, forces you to decide within weeks, to put up money and to generate income in your Spanish return at the worst possible moment: just as you have left the job.
- Who grants the options. Very often it is not the Spanish subsidiary that runs your payroll but the parent company. That affects the duty to withhold and pay on account, the payment on account that can be recharged to you, and the information the company reports about you. It is one of the biggest sources of mismatch between what the company reports and what should appear in your return.
- Early exercise and cashless mechanics, which in Spanish income tax produce completely different moments of taxation.
- Acceleration on a change of control and repurchase rights, which decide whether what you hold turns into money or into nothing on the day of the deal.
That is why the useful answer is not in the three letters on the cover of the plan but in the body of it. We read the grant and the full plan document, and that is where it emerges when the income arises and how much it is.
What nobody tells you: the American who lives here
The United States taxes its citizens on worldwide income wherever they live. A citizen or green card holder resident in Spain does not get to choose: they file in both places. And there the label on the plan matters again, but from the American side.
The problem is not paying twice — the treaty and the credit mechanisms exist for that — but that each state places the income at a different moment. If here the income arises on exercise and there, because it is an ISO, the ordinary tax is deferred until sale, the foreign tax credits may never meet in the same tax year and can go unused. This is not theory: it is the most repeated conversation on this line.
We are Spanish tax lawyers. We calculate your Spanish income tax, document the dates and tell you what risks each decision carries, but we do not advise on United States law and we do not interpret whether your option keeps or loses its qualified status there. Where there is an American component, the missing piece is a tax adviser in the United States, and the sensible arrangement is for both returns to be prepared with each aware of the other. We coordinate with whoever you appoint; we do not promise an outcome in a system that is not ours.
A proportion of the people who write to us believing they hold ISOs in fact hold NSOs, phantom options or units in a synthetic plan that never delivers shares at all. Each is taxed differently. The grant letter says which; the conversation with the human resources team sometimes does not.
If you came in on the inbound regime
Anyone taxed under article 93 of the Personal Income Tax Act has a different calculation again: the employment component of the equity comes into the Spanish return wherever it arose, while a later gain through a foreign broker may not come in at all. That makes the timing of an exercise worth looking at before rather than after. The comparison is on Beckham or the ordinary regime.
The in-between case: ISO or NSO: what it means there and what it means here
The table compares two labels on the assumption that the person holding them is an employee living in one place for the whole life of the plan. The files that reach us are rarely like that.
The person who changed country halfway through. The grant signed while resident in the United States, the vesting split between there and here, the exercise already living in Spain. The label on the plan has not changed, but the income is allocated according to where the work was done while the right was being earned, and each State applies its own allocation rule. That the two allocations do not match is nobody's mistake: it is the precise point at which the double taxation everyone then tries to relieve is born. Unwinding it takes both sets of figures side by side, and it is slow.
The person who is not an employee. Ordinary options are also granted to board members, advisers and independent contractors. Where there is no employment relationship, what is received is unlikely to be employment income: it fits better as income from a business activity, with everything that drags behind it in VAT, payments on account and the obligation to issue invoices. It is an arguable characterisation, it stands or falls case by case, and it is far better raised before exercising than during a review.
The person who exercised early and filed the corresponding election in the United States. That election brings forward the moment of taxation there. In Spain it has no equivalent and no direct effect: Spanish income tax will go on placing the income where its own rules place it. The result is that the two calendars separate, and relief for double taxation can end up stranded in different years on each side. What the American election does or does not achieve in the United States is a question for your adviser there; what we can tell you is what Spain will do with the same facts, and when.
What to look at before you touch anything
- The full grant letter, not the summary screen on the equity portal, and the plan document it refers to.
- The leaver clause: how many days there are to exercise from termination, and which event those days are counted from.
- Who grants and who runs the payroll, with the exact name of each entity.
- Your position in the United States: whether you are a citizen, a green card holder or neither. It changes everything that follows.
- The information returns the company has issued in your name there, and what was reported on them.
- Your residence calendar and days worked per country across the vesting period.
- Whether you are, or are about to be, on the article 93 regime, and in which tax year it begins or ends.
None of the above is advice on American law, and we do not give any. What we do is set out what Spain will charge, on what amount and in which year, so that whoever advises you there is working from the same timeline.
How we handle ISO or NSO: what it means there and what it means here
We start with the paperwork: grant, plan, vesting schedule and any later agreement. We fix the dates, place each item of income in its year and calculate what falls due, including the part attributable to periods worked outside Spain.
The comparison between the two forms of equity — the one you have to exercise and the one you do not — is on stock options or RSUs. The rest is on stock options and RSUs, and the form asks straight away for the plan documents.