The shift from documentary review to substance-based enforcement in Spanish tax controversy, and what it now asks of internationally mobile individuals and the structures through which they hold their affairs.
For most of the last decade, a Spanish tax inspection of an internationally mobile individual was a documentary exercise. The inspector confirmed that returns had been filed, that foreign assets had been declared, that the treaty had been applied to the right figure. The structure beneath the return was rarely the issue. That has changed.
Across 2025 and into 2026 the Spanish Tax Agency (the AEAT) has reoriented how it examines private clients with cross-border affairs. Inspections are now substance-driven, evidence-intensive and, increasingly, built around the concept of simulation. The most conspicuous example is the wave of audits of beneficiaries of the special regime for inbound workers under article 93 LIRPF, known as the Beckham regime, but the same method now runs through cross-border private client work as a whole.
A change of architecture, not of emphasis
The shift rests on data rather than rhetoric. The 2026 Tax Control Plan frames the agency’s priority as the verification of economic substance, not the formal accuracy of declarations, and its tools have caught up with that ambition. The Verifactu invoicing system, the expanded Financial Ownership File under Royal Decree 253/2025, and the transposition of DAC 8 with effect from 1 January 2026 give the AEAT a cross-checking capacity it did not have even two years ago.
The result is a different kind of inspection. The question is no longer whether the right boxes were ticked, but whether the account given on the return matches what actually happened. Inspectors now read bank flows, professional digital footprints, corporate communications and governance records, and they ask where decisions were really taken. A great many internationally mobile clients hold structures that are defensible on paper yet were never built to survive that examination. They carry an exposure today that did not meaningfully exist when the structure was put in place.
The Beckham regime as the leading indicator
Audits of Beckham beneficiaries are the clearest illustration. They seldom dispute the arithmetic of the Modelo 151 return; they dispute the legal premise of admission to the regime. The 2023 Startups Law widened eligibility to remote workers and certain digital nomads, the eligible population grew, and supervision has grown with it. Because the regime covers the year of relocation and the following five tax periods, and because its loss reaches back across every period still open under the four-year limitation in article 66 LGT, what is at stake in a single inspection is rarely one year of tax.
Three fact patterns recur. The first is the lightly resourced Spanish company that formally employs the impatriate while the operating invoices continue to flow through a related foreign entity. The second is the founder or consultant who works from a fixed base in Spain, often a home office, in a way that creates a permanent establishment of the foreign company. The third is the impatriate who keeps directorships and signing authority abroad, where the agency argues that the company’s place of effective management has moved to Spain. In each, the AEAT tends to decline the narrow path of a technical breach of article 93 and reach instead for recharacterisation through simulation, which allows it to revoke the regime retroactively and to apply a far heavier sanction.
Which article, and why it decides the case
Spanish anti-avoidance law offers three instruments, and identifying which one the inspector is actually using has become central to the defence.
Article 13 of the General Tax Act recharacterises a transaction by its true legal nature. Used on its own, where the underlying facts were disclosed, it carries no penalty.
Article 15, the conflict in the application of the norm, is the closest thing in Spanish law to a general anti-abuse rule. It requires a prior favourable report from the Consultative Commission and expressly excludes penalties. That procedural condition is a real safeguard: an assessment that ought to have travelled this route, but did not obtain the report, is void.
Article 16 governs simulation, and it is the gravest of the three. The agency must establish that the transaction did not occur as presented, that the parties intended something else, and that there was a deliberate intent to mislead. Where it succeeds, the regime falls retroactively and the conduct is treated as a very serious infringement, with penalties of between 100% and 150% of the tax avoided. Where the quota in dispute exceeds the threshold in article 305 of the Criminal Code, a finding of simulation is also the gateway to criminal exposure, which changes the character of the matter entirely.
The decisive battleground in 2026 is the space between these tools. We increasingly see assessments dressed as simulation under article 16 where the substance of the complaint is artificiality, which belongs under article 15. When that happens the assessment is vulnerable on two fronts at once: the Consultative Commission report was never sought, and the penalty exclusion that article 15 would have carried has been circumvented. The Supreme Court has shown a growing readiness to police the boundary, and it remains among the most productive lines of challenge open to the taxpayer.
Permanent establishment, and the sharper question of corporate residence
The condition in article 93 that the beneficiary obtain no income through a permanent establishment in Spain is now applied with unusual breadth, and it is worth separating two distinct consequences that the same facts can produce.
The first is a permanent establishment. Where an individual habitually works from a fixed place in Spain, and negotiation, decision-making or delivery occur there, the AEAT may treat that base as a permanent establishment of the foreign company under the Non-Resident Income Tax Law and the applicable treaty, taxing in Spain the profits attributable to it. The second, and more serious, is corporate residence. Where directorship and real decision-making sit in Spain, the agency may argue that the company’s place of effective management is Spanish, so that the company is itself tax resident in Spain under article 8.1 LIS and taxable here on its worldwide profits rather than on a Spanish slice. For the individual, either finding ends the regime. For the company, the gap between the two is the gap between a contained adjustment and the wholesale relocation of its tax residence. For founders, consultants and senior executives whose work is mobile by nature, that analysis belongs before entry into the regime, not after a notification arrives.
Evidence decides, and it has to be contemporaneous
One thread runs through all of this. The evidential standard expected of the taxpayer has risen, and the agency assembles its case forensically. A defence resting on explanation alone, however technically elegant, seldom displaces a well-built factual account. What carries weight is contemporaneous evidence answering three questions across the relevant years: what the legal and economic substance of the structure was, shown through contracts, mandates and board records that existed at the time; where decisions were actually taken, shown through travel, minutes and communications; and what the commercial rationale was, defensible without reference to any tax advantage. Material produced for the inspection itself counts for little, and the tribunals are well practised at telling a genuine record from a reconstruction. Audit readiness has to be designed in at the outset, not assembled under pressure once a letter has arrived.
The choices that follow
When an assessment does come, the path is settled: the inspection, then the Regional and Central Economic-Administrative Courts, then the contentious-administrative jurisdiction, and ultimately cassation before the Supreme Court. Two decisions tend to weigh most.
The first is whether to close the inspection by agreement. Under article 188 LGT an acta con acuerdo secures a 65% reduction in the penalty but waives the right to challenge; an acta de conformidad secures 30% while preserving it, with a further reduction for prompt payment without appeal. Which is right turns on the strength of the case and the appetite for litigation, and it should never be taken under time pressure.
The second, for clients exposed in more than one country, is the international dimension. A Mutual Agreement Procedure under the relevant treaty or the EU Tax Dispute Resolution Directive remains available, and closing an inspection by agreed record does not, following BEPS Action 14, foreclose later recourse to it. A defence in Spain has to be built with the home jurisdiction in view, and the home jurisdiction increasingly has to be built with Spain in view.
What it means
The direction of travel is not in doubt. The coming period will be defined by deeper data integration, sustained scrutiny of the internationally mobile, and a settled preference for substance over form. The clients who pass through it well will be those whose structures were built for substance rather than for documentary defensibility, and who treated audit readiness as ordinary discipline rather than as a reaction to a notification. The Spanish tax authority is no longer a checker of forms. It is a well-resourced regulator with the data to expose the gap between form and substance, and the work now rewards clarity, evidence and preparation far more than it rewards ingenuity.
Lullius is a tax boutique in Palma de Mallorca advising international private clients on Spanish tax, private wealth and tax controversy. The authors contributed the Spain chapter on trends and developments to the Chambers Tax Controversy 2026 Global Practice Guide. This note is general commentary, current to June 2026, and is not advice on any particular matter.
