Working Remotely From Another Country: Where the Tax Is Actually Due

Two different 183-day rules, and only one of them decides residence

The number appears twice in this field, in two instruments that do different work, and the sentence "under 183 days and you are fine" collapses them. The first appearance is in domestic law, where some countries use a day count as one of their tests for who is a tax resident. Spain does: Article 9 of Ley 35/2006 makes you resident if you spend more than 183 days of the calendar year on Spanish territory, and it adds that sporadic absences count towards that total unless you can prove tax residence somewhere else. France does not. Article 4 B of the Code général des impôts lists three alternative criteria — your foyer or principal place of stay, a professional activity carried on in France, and the centre of your economic interests — and none of them is a number of days. A person can be French tax resident having spent well under half the year in France, because the family home is there.

The second appearance is in tax treaties, and it does something else entirely. Once residence has been settled — by domestic law, and where two countries both claim you, by the tie-breaker in Article 4 of the applicable treaty — the treaty then allocates each kind of income. Article 15 is the article for employment income. Its first paragraph says pay is taxable only in the state of residence unless the employment is exercised in the other state, in which case that other state may tax the pay earned there. Its second paragraph is the exception that gives the state of residence the exclusive right back, and that exception is what everyone calls the 183-day rule. So the day count in Article 15(2) never decides where you live. It decides whether a country you visited to work gets to tax the slice of salary you earned while standing on its soil.

Three conditions, all cumulative, and the day count is only the first

Article 15(2) is written as a list joined by "and", not "or". The pay stays taxable only in the state of residence if: the recipient is present in the other state for periods not exceeding 183 days in aggregate in any twelve-month period commencing or ending in the fiscal year concerned; the pay is paid by, or on behalf of, an employer who is not a resident of that other state; and the pay is not borne by a permanent establishment which the employer has in that other state. Three conditions. All of them. The exemption from source-state tax is the reward for meeting the whole set, and failing any one of them hands the source state the right to tax the pay attributable to work done on its territory — not for the days over 183, but for every day worked there.

This asymmetry is why the rule is so often misread as generous. It is not a safe harbour that shelters short trips; it is a narrow relief for a specific, common pattern — the employee sent on a short assignment by a foreign employer at that employer's own cost. Take a French-resident engineer who spends four months in Germany on a project. If the German subsidiary is invoiced for her time, condition (b) or (c) fails on the substance of who really bears the cost, and Germany may tax the four months' pay even though 120 days is nowhere near 183. Conversely, a consultant who spends 200 days in a country fails condition (a) and the other two never even get read. The day count only ever matters when the other two are already satisfied.

Physical presence, not working days — and the window may not be the calendar year

The commentary on Article 15 settles the counting method: days of physical presence. Any day on which the person is present in the state, even for part of it, counts as a whole day. That includes the day of arrival and the day of departure, both counted in full; Saturdays and Sundays spent there; public holidays; days of holiday taken before, during or after the assignment; short breaks; and days of sickness, unless the illness is what prevented departure and the person would otherwise have qualified for the exemption. Days spent entirely outside the state do not count, and a day spent in transit while travelling between two other countries does not count. This is a deliberately blunt test, and its bluntness is the point: it can be verified from boarding passes rather than from timesheets.

The window is the second trap. The current model text counts across any twelve-month period commencing or ending in the fiscal year concerned — a rolling window, which means a stay split across two calendar years can still breach the limit. Many treaties in force were signed before that wording was adopted and still read "in the fiscal year concerned" or "in the calendar year". Which one governs your case depends on the specific treaty between the two specific countries, and on nothing else. This is the moment to read the actual bilateral text rather than a summary of the model: the two formulations give different answers for exactly the pattern that arises most often, a project running from autumn to spring.

The employer condition is where most cases are actually decided

Condition (b) asks who the employer is, and the answer is not automatically the entity on the employment contract. The commentary sets out a substance test — sometimes called the economic employer approach — that looks at who bears the risk and responsibility for the work, who instructs the worker, who controls the place of work, and, decisively, who ultimately bears the cost of the remuneration. If a group recharges the salary cost to the entity in the country where the work was done, that entity starts to look like the employer for treaty purposes even though no contract was signed with it, and the shelter of Article 15(2) disappears.

Tax administrations have built detailed doctrine on exactly this. Germany's finance ministry published a circular on the tax treatment of employment income under double taxation agreements on 12 December 2023 and amended it on 19 December 2025; the amendment strengthens the evidential weight of an employer certificate showing, as a percentage, which salary, ancillary wage and administrative costs have been recharged to the receiving entity on arm's-length terms. That is the administration telling you where it will look first. If your assignment involves a cost recharge, the recharge documentation is the file that decides the case, and it is worth getting right before the assignment rather than after the assessment.

Social security is a different system, with different numbers

Nothing in Article 15 has any bearing on which country's social security you belong to. Within the EU, the EEA and Switzerland that is decided by Regulation (EC) No 883/2004, whose general rule in Article 11(3)(a) is the law of the place where the activity is pursued. Article 12 carves out postings, letting a worker sent abroad stay in the home system where the anticipated duration does not exceed twenty-four months. Article 13 handles activity in two or more member states, and that is the article a remote worker usually lands in. Its implementing regulation, (EC) No 987/2009, gives the yardstick: Article 14(8) says a share of less than 25% of working time or remuneration is an indicator that a substantial part of the activity is not pursued in that state. Twenty-five, not one hundred and eighty-three.

That 25% threshold made ordinary hybrid work awkward: two days a week from home in a neighbouring country is 40%, which flips the whole payroll to the country of residence. The response was a multilateral framework agreement built on Article 16(1) of Regulation 883/2004, in force since 1 July 2023, under which cross-border telework in the state of residence of less than 50% of total working time can be disregarded, on joint application by employer and employee, so the employer's state keeps the affiliation. It binds only the states that signed it; Belgium acts as depositary and maintains the list, and several states joined later — Slovenia in September 2023, Italy in January 2024, Ireland in June 2024, Lithuania in May 2024, Estonia in February 2026. It is opt-in per case, not automatic, and it produces an A1 certificate that is the document a labour inspector actually asks for.

What the day count never decided: payroll and permanent establishment

Two further questions are routinely folded into the 183 days and belong to neither. The first is payroll withholding: whether an employer must register and operate wage withholding in the country where the employee sits is a matter of that country's domestic law, and a country can require registration even where a treaty ultimately exempts the pay, because the treaty relief is claimed rather than assumed. "We do not have payroll there" is a statement about the employer's systems, not about the tax that is due. The second is the permanent establishment of the employer, which lives in Article 5 of the same model treaty and turns on whether a fixed place of business is at the enterprise's disposal, or whether someone habitually concludes contracts on its behalf. A home office can be relevant to that analysis; the number of days its occupant spent in the country is not the test.

The practical order of operations follows from all this. Settle residence first, under domestic law and then under the treaty tie-breaker, because everything downstream depends on it. Then, for each country where you physically worked, run Article 15(2) as a three-part test and be honest about condition (b). Then, separately and with different numbers, work out the social security position and get the A1 before you travel, not after. Then ask what your employer needs to do about registration and withholding in each place, which is a domestic-law question in each place. Keep a dated record of physical presence as you go — the day count is the one part of this that is impossible to reconstruct a year later, and it is the part an administration will ask you to prove.

Frequently asked questions

I spent 120 days working in Spain for my French employer. Am I safe from Spanish tax?

Only if the other two conditions also hold. One hundred and twenty days clears the day count, so condition (a) is satisfied. Now ask whether your salary for those days was ultimately borne by a Spanish entity — a subsidiary, a branch, a client to whom your time was recharged. If it was, condition (b) or (c) fails on substance and Spain may tax the pay attributable to all 120 days, not the excess over any threshold. Ask separately whether your presence and pattern of work in Spain triggered Spanish residence under Article 9 of Ley 35/2006, which counts days differently and answers a different question, and whether an A1 was in place for the social security side.

Does the 183-day count reset on 1 January?

It depends on the treaty in front of you, and this is not a detail. The current OECD model text counts over any twelve-month period commencing or ending in the fiscal year concerned, which is a rolling window: 100 days from October to December and 100 days from January to March breach it, even though neither calendar year does. Many treaties still in force predate that wording and count within the fiscal or calendar year, in which case the same pattern stays inside the limit on both sides. Read the actual bilateral treaty text for the two countries involved; the model is a template, not the law that applies to you.

My employer says it cannot run payroll in that country, so I cannot be taxed there. Is that right?

No. Those are two unrelated statements. Whether tax is due in a country follows from that country's domestic law as limited by the treaty; whether your employer has a payroll registration there is an operational fact about your employer. Many countries will require the individual to file and pay directly where no local withholding exists, and some will require the foreign employer to register precisely because an employee is working there. The absence of payroll is a reason to check what filing obligation falls on you personally, not a reason to conclude that nothing is owed.

Do I need an A1 if I work two days a week from home in a neighbouring country?

Yes, and this is the case the framework agreement was written for. Two days out of five is 40% of your working time in your state of residence, which is above the 25% indicator in Article 14(8) of Regulation 987/2009 and would ordinarily move your affiliation to the country you live in. Since 1 July 2023, if both states have signed the framework agreement, employer and employee can jointly apply to keep the employer's state competent, provided the cross-border telework stays under 50%. The application produces an A1 certificate; without one, you have no portable evidence of which system you belong to, and it is the certificate rather than the argument that gets accepted at an inspection.

Can my working from home create a permanent establishment for my employer?

It can, and the day count has nothing to do with it. That question lives in Article 5 of the treaty, which asks whether a fixed place of business is at the enterprise's disposal — a home office used continuously for the business, especially where the employer requires it and provides no alternative, is a recognised fact pattern — or whether a person habitually concludes contracts in the enterprise's name. Sales roles are the sharper risk, because the second limb catches them regardless of where the desk is. This is a question about your employer's corporate tax exposure, not your own income tax, and the two are decided under different articles on different facts.