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Every cross-border worker has heard it: “stay 183 days and you become a tax resident.” The rule exists in every one of the five countries Taxmora covers — and in every one of them it is only one of several ways to become a resident, none of them the most common one in practice. People who plan around the day count alone get surprised by exactly the tests they never heard of.
How each country actually decides residency
| Country | Residence test | Statute |
|---|---|---|
| Spain | >183 days; OR centre of economic interests in Spain; OR spouse + dependent minor children resident in Spain (rebuttable presumption) | art. 9 LIRPF |
| Portugal | >183 days; OR shorter stay with a permanent home there suggesting intent to keep it | art. 16 CIRS |
| Germany | A dwelling used as residence (Wohnsitz) — no minimum days; OR habitual stay over six months (gewöhnlicher Aufenthalt) | § 8 + § 9 AO |
| Netherlands | Facts and circumstances: where your personal and economic life is centred (home, family, work, registrations) | art. 4 AWR |
| United Kingdom | The Statutory Residence Test: automatic overseas tests, automatic UK tests (183+ days, home + work), and a ties-based middle zone | ITA 2007 s.5 (HMRC RDR3) |
Read that table again and notice what is missing: in Germany there is no day count at all — a flat you keep available counts. In Spain, having your spouse and kids in Spanish schools can make you a resident on day one, days irrelevant. In the Netherlands, no statute even mentions a number — the whole analysis is “where is your life”. The 183-day rule is usually the least of what decides your case.
Day counting is its own sport
- Most countries count a day by physical presence at midnight; split days, transit days and “partial” days are exactly where disputes happen.
- Spain and Portugal count days across the calendar year; the UK uses tax years (6 April – 5 April) and its own UK-day definition — the same travel pattern can produce different counts in different countries.
- Country of residence fights are resolved between states, not by you: when two countries both claim you, the double-taxation treaty’s tiebreaker (OECD Model, art. 4(2)) walks through permanent home → centre of vital interests → habitual abode → nationality.
The trap nobody warns you about: residency and social security are separate systems
Tax residency and social-security liability are decided by different rulebooks. Staying under 183 days does not keep you out of a country’s social-security net if you work there — and within the EU/EEA the coordination rules (A1 certificates, the “last employer country” principle for remote workers) decide which system you pay into, independent of the 183-day count. This is the single most common surprise in remote-work setups.
What being resident in each country is worth: €80,000 as a resident
| Country (residency year label) | Tax + social contributions | Net take-home | Effective rate |
|---|---|---|---|
| United Kingdom (2025-26) | £19,432 | £60,568 | 24.3% |
| Germany (2026, provisional) | €22,763 | €57,236 | 28.4% |
| Spain, Madrid (2025) | €23,281 | €56,719 | 29.1% |
| Portugal (2026, provisional) | €27,238 | €52,761 | 34.1% |
| Netherlands (2026) | €29,532 | €50,467 | 36.9% |
The same €80,000 spans a €10,000 range across the five systems — and this table is the boring case. Arrival regimes (Beckham, IFICI, the 30% ruling, UK FIG) sit on top of residency, and the country guides cover each one with the same engine-computed approach.
How Taxmora assesses residency
The residency module implements the tests above per country — day counts, economic-interests checks, the Spanish family presumption, the UK ties matrix from RDR3 — and then applies the treaty tiebreaker when two countries both claim you. It is a planning tool with the statute cited on every answer, not a substitute for a ruling. Where the honest answer is “this needs an adviser”, the assessment says so.
Frequently asked questions
- Is it exactly 183 days or more than 183?
- In Spain and Portugal the threshold is crossed above 183 days of presence. But do not fixate on the number: the economic-interests and habitual-residence tests trigger at any day count.
- Can two countries both consider me a tax resident?
- Yes, under domestic law that happens regularly. The double-taxation treaty between the two countries then assigns one residence via the tiebreaker chain. You still have to file correctly in both places in the meantime.
- If I stay under 183 days, do I avoid social security too?
- No. Social-security coordination is a separate rule system. In the EU/EEA a remote worker usually owes contributions where the work is performed or where the employer sits, regardless of the day count.
- I keep a flat in Germany but live mostly in Spain. Am I a German resident?
- Quite possibly — a dwelling available for your use (Wohnsitz) is enough under § 8 AO, with no minimum days. The treaty tiebreaker may assign residency to Spain, but the German dwelling still needs managing correctly.
Run the numbers yourself
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