Belgian Tax Resident with a Portuguese Company: Cayman Tax & Double Taxation
Audrey Marques
Consultant in business establishment & company formation in Portugal
Founder of Business Portugal, Audrey supports French-speaking entrepreneurs in setting up their company in Portugal and opening their bank account. She coordinates a network of partners (accountant, tax adviser) and points clients to the right contacts, she is neither an accountant, nor a tax adviser, nor a lawyer.
Many Belgian entrepreneurs imagine that registering a company in Portugal shelters their income from the Belgian tax authorities. The reality is more nuanced. As long as you remain an "inhabitant of the Kingdom", meaning your home or the seat of your wealth is in Belgium, you are taxable on your worldwide income. And Belgium has a specific mechanism, the Cayman tax, designed precisely to look through certain lightly taxed foreign structures. Understanding this before you set up in Portugal saves you from building a tax saving that exists only on paper.
Business Portugal is a setup and incorporation consultant: we coordinate and connect. Reading the Cayman tax closely, applying it to your case and reconciling it with the Belgium-Portugal treaty is the work of a partner tax adviser, never of a quick counter-top shortcut. What follows explains the logic in plain terms, so you ask the right questions at the right moment, not to replace tailored advice.
What the Cayman tax is, in a few words
The Cayman tax is the Belgian equivalent of so-called CFC (controlled foreign company) rules. It is set out in articles 5/1 and 220/1 of the 1992 Income Tax Code (the CIR 92). Its principle is fiscal transparency: rather than waiting for a distribution, the authorities tax directly, in the hands of the Belgian resident founder, certain income received by a lightly taxed foreign "legal construction". In other words, the structure is looked through as if it did not exist, and the income is taxed as though it were directly yours.
The founder, for the purposes of this mechanism, is not only the person who set up the entity: the notion also covers holders of the economic rights and, in some cases, heirs. The central idea is to neutralise the screen that a foreign entity would create when its main purpose is to park income away from Belgian tax. As long as the structure receives income and the conditions are met, transparency applies, whether or not anything is actually paid out to Belgium.
What it really targets: passive, not operational
It is essential to understand what the Cayman tax targets first and foremost: lightly taxed passive, wealth-holding constructions. Think of shell companies holding a securities portfolio, cash, rights or real estate assets, with no real economic activity, whose function is to capture passive income in a low-tax environment. It is this kind of "letterbox" structure that the Belgian legislator wanted to render transparent.
A genuinely operational Portuguese company, one that carries on a substantial economic activity, employs people or organises itself on the ground and generates trading income, does not fall under the same logic. Taxed at Portugal's normal IRC rate (19%, or 15% for SMEs), it sits well above the very low taxation the mechanism targets, and is therefore in principle outside its scope. The mechanism does, moreover, provide nuances and exclusions for entities carrying on an effective activity. But be careful: the precise application to a real operational company is assessed case by case and must absolutely be validated by a tax adviser. The line between a substantial activity and a shell dressed up as one is not binary, and that is exactly where costly mistakes hide.
The treaty is no obstacle
Many hope that the double taxation treaty between Belgium and Portugal, signed on 16 July 1969 and amended by a 1995 protocol, neutralises the Cayman tax. That is not the position of the Belgian authorities. In its circular 2024/C/79, the administration considers that the Belgium-Portugal treaty does not stand in the way of applying the Cayman tax. Transparency can therefore apply even where a treaty exists between the two countries.
The reason lies in how treaties work: they allocate the right to tax between states over identified income, but they are not designed to stop a state from taxing its own resident, by transparency, on income held in a foreign structure. It is a technical distinction, and it is precisely the kind of point only a tax adviser should settle for your situation. The takeaway is simple: do not rely on the treaty as an automatic shield against the Cayman tax.
The real risk, and how to avoid it
For anyone who remains a Belgian tax resident, the real risk is not in Portugal but in Belgium. Setting up a Unipessoal Lda or a Lda in Portugal does not move your residence or your worldwide taxation. If the structure looks like a lightly taxed wealth-holding construction, the Cayman tax can apply; if it is run from Belgium, a risk of reclassifying the place of effective management is added on top. A Portuguese address is never enough. What matters is real substance: your life, the company's management and its activity must genuinely be in Portugal for the country to become tax-relevant.
As an indicative figure to be confirmed, the Belgian corporate income tax sits in the region of 25% (with a reduced 20% rate on the first 100,000 EUR for small companies under conditions) and Belgian VAT at 21%. On the Portuguese side, IRC is 19% standard and 15% for SMEs on the first 50,000 EUR, and IVA is 23%. These 2026 orders of magnitude are to be confirmed, and any specific case must be validated with a tax adviser. Our role as a consultant is to build a coherent, substantial Portuguese presence and to connect you with a partner Contabilista Certificado and a tax adviser for the close reading of the Cayman tax and the treaty. If your project plays out between Belgium and Portugal, let's take the time to clarify your real situation before any decision.
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