Tax treaties: why they change everything when you leave

The starting point is not the tax treaty but French law. Article 4 B of the General Tax Code (code général des impôts) defines who is tax domiciled in France. It covers four categories of people.

1. Those whose household or main place of stay is in French territory;
2. those who carry on a professional activity there, whether salaried or not, unless they can show that this activity is carried on in France on an ancillary basis;
3. those whose centre of economic interests is in France;
4. state employees performing their duties or on assignment in a country where they are not subject to a personal tax on all of their income.

The administrative guidelines are explicit about the scope of this list: “For a taxpayer to be domiciled in France, it is sufficient for one of the criteria to be met.” The criteria are alternative, not cumulative. This is the sentence with the heaviest consequences in the entire system.

The practical consequence is counter-intuitive for many people leaving. Living abroad all year round does not protect you: it is enough for the centre of economic interests to have remained in France for French domicile to stand. A company director based in Dubai whose income still comes mainly from a French company meets one criterion, and one is enough.

Conversely, keeping a home in France is not necessarily enough to establish the household there if the family has genuinely followed and the centre of interests has shifted. The assessment is factual, and it rests on a body of evidence, not on declarations of intent.

This is why counting days, to which many reduce the question, is only one element of the first criterion — the main place of stay — and says nothing about the other three.

The tax treaty only comes into play at the second step, and only in the event of a conflict. If France considers a person to be domiciled there and the other state also considers them resident, two domestic laws contradict each other. The treaty concluded between the two states settles the matter.

Its precedence is not a favour: it follows from the hierarchy of norms, “the rule of international law always prevailing over domestic law, by virtue of article 55 of the Constitution of 4 October 1958”.

Most tax treaties organise this tie-breaking through a series of successive criteria — often the permanent home, then the centre of vital interests, then habitual abode, then nationality, and as a last resort an agreement between tax authorities. They are applied in order: you only move on to the next one if the previous one does not settle the matter.

It arises for every departure, but it becomes critical in three situations: when the family does not leave at the same time as the person; when the activity or income remains linked to France; and when the host country has not concluded a tax treaty with France, in which case there is no tie-breaking mechanism and double taxation is not resolved by any text.

This last case should be checked before choosing a destination: the absence of a tax treaty is a parameter of the plan, just like a tax rate.

1. Check, country by country, whether there is a tax treaty with France, and read its residence clause before committing;
2. go through the four criteria of article 4 B one by one, not just the day count;
3. document the move as it happens — lease or purchase locally, schooling, bank accounts, contracts, professional changes — because the evidence is built before an audit, never during one;
4. treat where your income is attached as a project separate from the move itself: it is the centre of economic interests that is most often at issue.

Tax treaties are not interchangeable. The order of the tie-breaker criteria, the definitions used and the exceptions vary from one text to another, and some older treaties contain specific clauses. No general reasoning can replace reading the applicable treaty.

We do not publish a list here of the countries linked to France by a tax treaty: it changes, and we do not have a consolidated, dated official source to cite for the whole network. It must be checked case by case on the tax authority's website.

Finally, assessing the household and the centre of economic interests is a factual analysis, regularly brought before the courts. Two similar situations may receive different answers; this is a structural uncertainty of the system, not a gap in the information.