The four categories
The governing law distinguishes four families. They determine the qualification regime that applies.
Craft, covering most construction trades.
Trade, concerning notably merchant activities linked to construction.
Industry, covering production activities of an industrial character.
Certain liberal professions, including architects and consulting engineers.
These four categories fall under a single governing text, but qualification conditions and temporary-services formalities differ within it.
That difference is developed in the article on who must notify.
| Family | What it groups | Qualification regime |
|---|---|---|
| Principal trades | Structuring construction activities | Qualification required |
| Secondary trades | Complementary activities | Lighter qualification |
| Related activities | Site-related services | Depends on the activity |
| Free activities | Unregulated services | No qualification required |
What changes between the categories
Three practical differences.
The requirement of professional qualification. It is frequent in craft, where trades are regulated, and it is assessed differently according to the activity.
The formalities for temporary provision. Craft and industrial firms notify; those in commercial or liberal professions subject to a permit are exempt where they come from the European area or Switzerland.
Professional supervision. Regulated liberal professions are subject to distinct professional-body oversight, which comes on top of establishment law.
A single project may therefore involve parties in different categories, each with their own obligations.
Why a classification does not transpose
This is the most important point in this article. The qualification required depends on which family the activity falls into.
Activity nomenclatures do not overlap from one country to another.
An activity classed in one category in the home country may fall in another in Luxembourg, with direct consequences for formalities.
The scope of a trade may also differ. What a job title covers in one country is not necessarily what it covers in another.
A firm that assumes its category rather than checking it therefore runs a real risk, and that risk often surfaces only at an inspection.
This guide deliberately lists no activities. An unverified list would be more dangerous than useful, a firm possibly recognising itself in it wrongly.
The case of mixed activities
A frequent and poorly handled situation.
A firm sometimes carries on several activities falling in different categories.
The permit covers the activities for which it was granted, and adding an activity not covered calls for a fresh application.
A firm that widens its offering without reviewing its permit is therefore partly trading without title, often unaware of it.
This point connects with the duty to maintain covered in the article on the conditions to meet.
The method of checking
Three steps, in order of reliability.
Ask the administration responsible for business permits, the only body that classifies an activity under Luxembourg law.
Consult the competent professional chamber, which supports the steps for its sector.
Describe your actual activity rather than its title, classification bearing on what is in fact carried on.
The third step conditions the reliability of the first two: an approximate description produces an approximate answer.
What this means for a professional
Four rules.
Have your activity classified by the administration, without relying on an assumed correspondence.
Describe the activity actually carried on, not the commercial title.
Check the permit's coverage before widening any offering.
Identify each party's category on a multidisciplinary project, obligations differing.
This article reflects the rules at the date of checking and serves professional orientation. It does not constitute legal advice.