How NACE is structured

NACE is a strict hierarchy with four levels. Every activity is placed in exactly one class at the lowest level, and every class rolls up to exactly one group, one division and one section — no overlaps, no double parenting.

The four levels are:

· Section — 21 broad domains identified by a single letter, A to U (for example, A Agriculture; C Manufacturing; J Information and communication).

· Division — 88 mid-level groupings identified by a two-digit code (for example, 62 Computer programming, consultancy and related activities).

· Group — 272 finer groupings identified by a three-digit code (for example, 62.0 Computer programming, consultancy and related activities).

· Class — 658 leaf-level categories identified by a four-digit code (for example, 62.01 Computer programming activities).

A NACE class code always looks like DD.CC — two digits, a dot, two more digits. The two digits before the dot identify the division; the first digit after the dot identifies the group inside that division; and the last digit identifies the class inside that group.

So 62.01 decomposes as: division 62 (Computer programming, consultancy and related activities), group 62.0 (same title — the only group in the division), class 62.01 (Computer programming activities). Section J is not part of the code itself but is implied by the division number: divisions 58–63 all sit under section J.

The Regulation stops at four digits. National statistical institutes are then free — and, in practice, universally choose — to extend the last class with a fifth digit that captures nationally interesting sub-activities. This is where the national dialects live: France's NAF adds a trailing letter (6201Z), Germany's WZ adds a numeric fifth digit (62.01.0), Portugal's CAE compresses to a five-digit numeric code (62010), the Netherlands' SBI uses a decimal fifth digit (62.01).

The critical invariant, guaranteed by regulation, is that the first four digits of any national code are, by construction, a NACE class. This is what makes cross-border translation possible: strip the fifth digit, and you are back on the EU backbone.

Each class ships with an official explanatory note that describes what the class includes and — critically — what it excludes. Excludes clauses often point to the class where the excluded activity actually belongs. These notes are the arbiter when two classes look like they could both fit: they are, in effect, the case law of NACE.