February 10, 2026 — The 183-day rule survives in popular conversation, in onboarding documents handed to executives by relocation consultants, and in the headline summaries of cross-border tax guides. It has not survived in the actual tax codes of the jurisdictions whose tax authorities now decide residency disputes. The rule that once allowed an individual to determine their tax residence by counting days on a calendar has been replaced, in France, the United Kingdom, Italy, and Spain, by multi-factor tests in which day-counting is one input among several. The shift has been gradual, jurisdiction-specific, and largely invisible to those who have not been audited under the new framework. It is also irreversible. This article reads the four major European residency regimes in parallel and identifies the operational consequences for individuals and the entities advising them.

The premise underlying the historical 183-day standard was that physical presence, measured in days within a single tax year, was an adequate proxy for the centre of an individual's life. That premise was always defective. A senior executive could spend two hundred and twenty days in country A while maintaining a family home, school enrolment for children, principal banking relationships, and professional registrations in country B. The 183-day rule, applied mechanically, would assign tax residence to A. The actual centre of that individual's life, by any reasonable interpretation, was B. Tax authorities understood this. Courts understood this. The legislative response, across every major European jurisdiction, has been to add criteria — and to add them in such a way that physical presence becomes one factor in a balancing test rather than a determinative count.

France: Article 4B CGI and the four-criterion test

The French regime is structured around Article 4B of the Code général des impôts. The article provides four criteria, of which the satisfaction of any single one is sufficient to establish French tax residence. The criteria are: foyer ou lieu de séjour principal en France; activité professionnelle principale en France, unless that activity can be justified as accessory; centre des intérêts économiques en France; and the consequence of any combination of the foregoing.

The foyer concept has been refined through case law that now has the consistency of a black-letter rule. The foyer is the place where the individual has their principal personal interests, defined typically by reference to family — spouse and minor children — but also by reference to the location of the principal residence and the centre of social and professional life. An individual who maintains a family home in France with a non-working spouse and school-age children will, in essentially every case, be held to have a foyer in France even if their professional activity is conducted abroad and even if their physical presence in France falls below the conventional 183-day threshold. The distinction between foyer and lieu de séjour principal is significant: the foyer test focuses on the location of personal interests; the lieu de séjour principal test focuses on physical presence and applies in the absence of a clearly identifiable foyer.

The professional activity criterion has been the principal battleground in French residency disputes for the past decade. The text of Article 4B refers to activité professionnelle principale and provides that the criterion is satisfied unless the activity can be justified as accessory. The administrative interpretation has been that an activity is accessory only if it is materially less significant than another professional activity conducted elsewhere, with significance measured by reference to time devoted, revenue generated, and economic importance to the individual. An individual who departs France and continues to derive substantially all professional income from a French source — for example, by maintaining a French SAS that pays them management fees or a French clientele that pays them consulting fees — has, under the prevailing administrative interpretation, not displaced the activité professionnelle principale criterion. The activity remains French; it is merely conducted from a non-French location.

The centre des intérêts économiques criterion has been used by the French administration with increasing frequency in cases where the foyer criterion is contested or where the activité professionnelle principale criterion is unclear. The criterion focuses on the location of the individual's principal investments, the source of their principal income, and the place from which they administer their wealth. The doctrine has evolved to treat retained corporate ownership, even passive, as a centre des intérêts économiques connection. An individual who has retained ownership of a French operating company — even one managed by salaried executives in France — has retained a centre des intérêts économiques in France for purposes of Article 4B.

The consequence of these refinements is that the practical threshold for clean French non-residence is materially higher than the 183-day rule would suggest. An individual who departs France while maintaining family in France, retaining French source income, or retaining French-based corporate interests cannot rely on day-counting alone. The Convention France-UAE of July 19, 1989, provides tie-breaker rules in cases of dual residence, and in particular Article 15 allocates employment income to the state where the employment is exercised. But the tie-breaker only operates where dual residence has first been established, and the threshold for French residence under Article 4B is lower than the popular conception assumes.

United Kingdom: the Statutory Residence Test and its progeny

The United Kingdom replaced its long-standing common-law residency framework with the Statutory Residence Test, in force from April 6, 2013. The test was constructed to provide certainty: a flowchart of automatic tests, sufficient ties tests, and presence calculations that, in principle, allowed any individual to determine their residency status by reference to objective criteria.

In practice, the SRT has produced a more complex regime than the common-law framework it replaced, and it has migrated steadily toward a multi-factor analysis as the case law has accumulated. The test contains three layers. The automatic overseas tests, which conclusively establish non-residence if any are satisfied. The automatic UK tests, which conclusively establish residence if any are satisfied. And the sufficient ties test, which applies where neither the automatic overseas nor the automatic UK tests are determinative.

The sufficient ties test counts days of presence in the United Kingdom against five connecting factors: a UK family tie, a UK accommodation tie, a UK work tie, a ninety-day tie based on prior years, and a country tie based on the relative time spent in the UK versus other countries. The number of ties an individual can have without becoming UK resident depends on their day-count and on whether they were UK resident in any of the prior three tax years. An individual leaving the UK for the first time can have up to four ties without becoming resident, provided their day-count is sufficiently low; an individual returning to UK territory can be resident with fewer ties at higher day-counts.

The administrative interpretation of each tie has been the principal source of post-2013 doctrine. The accommodation tie, in particular, has produced a body of guidance that practitioners now refer to with the same fluency as the underlying statute. An individual who maintains a UK accommodation that is available to them for a continuous period of ninety-one days and which they use for at least one night during the tax year has an accommodation tie. The availability test has been interpreted to capture not only owned property but also rental arrangements, family member properties used by the individual, and even hotel arrangements where the booking is sufficiently long-term. The exclusion of holiday homes used for fewer than fifteen nights has been held to apply restrictively.

The work tie has produced equally extensive interpretation. The criterion is met if the individual works in the UK for forty days or more in the tax year. The definition of working day captures any day on which the individual works for more than three hours, regardless of where the work is conducted within the UK. The forty-day threshold is annual, not cumulative, and it does not aggregate with related counts. But the administrative practice is to interpret work day broadly: an executive who attends a board meeting in London for three hours and then conducts no further UK work has used one of their forty days; an executive who participates in a video call from a UK location for three hours has, in the prevailing administrative interpretation, used one of their forty days.

The combined effect is that an individual leaving the United Kingdom to establish foreign residence cannot rely on a clean day-count. The day-count must be combined with the absence of sufficient ties, and the determination of those ties involves judgment calls that are inherently fact-sensitive. HMRC has, in the post-2013 period, developed a strong audit practice around the SRT, and the resolution of disputed cases has been slow and resource-intensive.

Italy: residence, AIRE, and the iscrizione anagrafica

The Italian regime contains a feature that has no direct equivalent in the French or British systems: the role of administrative registration as a determinant of tax residence. Article 2 of the Testo unico delle imposte sui redditi provides that an individual is resident in Italy if, for the greater part of the tax year, they are registered in the Italian population registry, have their domicile in Italy, or have their residence in Italy. The three criteria are alternative; satisfaction of any one is sufficient.

The administrative registration requirement, the iscrizione anagrafica, has been the source of considerable litigation. An individual who departs Italy is required to register with AIRE — Anagrafe degli Italiani Residenti all'Estero — to formalise their non-resident status. AIRE registration is not in itself sufficient to establish non-residence — the substantive criteria of domicilio and residenza must also be displaced — but failure to register with AIRE creates a strong presumption of continuing Italian residence that is difficult to overcome.

The domicilio concept in Italian tax law has been interpreted to mean the centre of an individual's principal interests. The interpretation closely tracks the French foyer concept but with somewhat broader scope: domicilio captures economic and professional interests as well as personal interests, and the Italian courts have held that the criterion is satisfied where the individual's principal economic affairs are administered from Italy, even if the individual's family is located elsewhere.

The Italian Agenzia delle Entrate has, in the post-2020 period, intensified its audit practice on individuals claiming non-resident status. The principal target has been individuals who relocated to lower-tax jurisdictions — the United Arab Emirates, Switzerland, Monaco, Portugal — while maintaining significant Italian economic interests. The administrative position has been to scrutinise the AIRE registration, the actual displacement of personal and economic centre, and the substance of the foreign residence. The cases that have reached the Corte di Cassazione have generally favoured the administration where the individual maintained Italian assets, Italian source income, or Italian family structures while claiming foreign residence.

An additional feature of the Italian regime is the regime degli impatriati, an inbound tax incentive designed to attract talent to Italy. The regime provides substantial reductions to the tax base for qualifying inbound workers. The regime has been used aggressively as a recruitment tool by Italian employers and has, in turn, raised the visibility of cross-border mobility to the Agenzia delle Entrate. The interaction between the regime degli impatriati and the residency analysis has produced its own body of administrative doctrine, particularly in cases of individuals who depart Italy, return under the regime, and depart again.

Spain: the centre of vital interests test and the new wealth dimension

The Spanish regime is constructed around Article 9 of the Ley del Impuesto sobre la Renta de las Personas Físicas. The article provides three criteria. First, that the individual remains in Spanish territory for more than 183 days during the calendar year, with sporadic absences not interrupting the count unless the individual proves tax residence in another country. Second, that the principal core of the individual's economic activities or interests, directly or indirectly, is located in Spain. Third, a presumption of residence where the spouse and minor children habitually reside in Spain, unless rebutted.

The Spanish regime is interesting because of the operation of the second criterion — the centre of economic interests test — and the way the Spanish administration has interpreted it. The test focuses on the location of the individual's principal source of income, the location of their principal investments, and the place from which they administer their economic affairs. The administrative interpretation has, in recent years, included passive ownership of Spanish real estate as a contributing factor; significant Spanish-source dividend income as a contributing factor; and the location of investment management activities as a contributing factor.

The Spanish wealth tax — which has been progressively reactivated and modified through the 2020 to 2025 period — has added a dimension to residency disputes that the French and Italian regimes do not have at comparable scale. An individual who is held to be Spanish tax resident is subject not only to income tax on worldwide income but also to wealth tax on worldwide assets. The wealth tax base includes financial assets, real estate, business interests, and certain personal assets. The cumulative effect on a high-net-worth individual incorrectly claiming non-resident status can therefore exceed pure income tax exposure by a significant margin. The Spanish administration is aware of this and has prioritised the audit of high-net-worth non-resident claims accordingly.

The Beckham Law, the Spanish inbound regime that allows qualifying expatriates to be taxed at flat rates on Spanish-source income for a period of years, operates as a complement to the residency framework. The regime requires positive election by the inbound individual and creates a six-year window during which the individual is treated as non-resident for certain purposes despite being physically present in Spain. The interaction with the residency analysis is technical and has been the subject of administrative interpretation through 2024 and 2025.

The convergence: substance over arithmetic

What unites the four regimes is the structural shift from arithmetic to substance. The 183-day count has not disappeared. It remains a criterion in each system. But it has been demoted to one input among several, with the others — family, economic interests, accommodation, professional activity, registration — operating either in parallel or as backstops where day-counting alone is inconclusive.

The practical consequence for individuals contemplating relocation is that the analysis has become more demanding. A clean change of residence requires not only physical relocation but the displacement of personal centre, the displacement of economic centre, the displacement of professional centre, and, in some jurisdictions, the formal registration of the change. The advisory function has shifted accordingly. Pre-2013, residency advice was largely about days and dates. Post-2020, residency advice is about substance: the establishment of a real foreign foyer, the displacement of family arrangements, the migration of economic interests, the registration with relevant administrative bodies, and the maintenance of evidence for the audit that may follow.

The audit practice has intensified in parallel. The French DGFiP, HMRC, the Italian Agenzia delle Entrate, and the Spanish Agencia Tributaria have all developed dedicated functions for the audit of individuals claiming foreign residence. The functions cooperate informally and, increasingly, formally through the framework of the Common Reporting Standard and bilateral exchange-of-information arrangements. An individual whose residency claim depends on a defensible substance position must now anticipate that the position will be tested.

The dossier the new regime requires

The evidentiary record that supports a defensible non-residence claim has expanded materially. Twenty years ago, the principal evidence was passport stamps and a residency certificate from the destination jurisdiction. Today, the principal evidence is a combination of physical presence records, foyer evidence, economic centre evidence, and substance evidence in the destination jurisdiction.

The physical presence record must be capable of withstanding a multi-year reconstruction. Calendar evidence, flight records, hotel receipts, and electronic transaction logs are the typical sources. Practitioners increasingly recommend that individuals maintaining a defensive residency position keep contemporaneous records — a calendar exported monthly, flight itineraries archived, accommodation receipts retained — in a single repository that can be produced in response to an audit request without the gaps and reconstruction errors that often appear when records are assembled retrospectively.

The foyer evidence focuses on the displacement of the personal centre. A child enrolled in a foreign school produces school records, transportation arrangements, and daily life evidence. A spouse with foreign professional activity produces employment evidence, foreign banking, and foreign social affiliations. A residential property in the foreign jurisdiction produces lease or ownership documents, utility bills, and insurance arrangements. Each of these elements is, in isolation, modest. In aggregate, they constitute the foyer record.

The economic centre evidence focuses on the displacement of investment management, the source of income, and the location of principal banking. An individual whose principal investments are administered from a foreign jurisdiction, whose principal source of income is generated abroad, and whose principal banking relationships are foreign has constructed a defensible economic centre. The complication is that displacement is rarely complete: most individuals retain some assets, some income sources, or some banking in the originating jurisdiction. The question is whether the residual elements are sufficiently significant to constitute a continuing centre of economic interests under the relevant statutory criterion.

The substance evidence in the destination jurisdiction is, in some respects, the most consequential element. A residency claim based on a UAE residence visa is materially stronger when supported by evidence of physical presence, banking activity, lease of accommodation, and integration into the local economic environment. The same is true for Switzerland, Monaco, Portugal, or any other destination. The destination jurisdiction's documentation is, paradoxically, the principal defence against the originating jurisdiction's audit.

Conclusion: the rule that survives in the popular imagination

The 183-day rule survives in onboarding documents, in popular conversation, and in the headline summaries that practitioners use when explaining cross-border mobility to clients who have not encountered the technical detail. It survives because it is intuitive, because it provides a clear answer in a domain where ambiguity is the norm, and because the alternative — a multi-factor analysis of substance — is more demanding to articulate.

It does not survive in the tax codes that determine residency disputes. France, the United Kingdom, Italy, and Spain have moved to a multi-factor framework in which day-counting is one of several inputs. The shift has been gradual but it is now complete. An advisor or individual who organises their cross-border position around the 183-day rule alone is operating with a model of residency that has not been current for at least a decade and, in most respects, longer. The next decade of residency disputes will be litigated under the multi-factor framework, and the architecture of cross-border mobility planning is converging around it.