How do national fifth levels differ?

National fifth levels differ because each country adds its own finer breakdown inside the European class level, for its own statistical needs, and no two countries are required to add the same breakdown. The European classification stops at the class, with four digits. National classifications add a fifth level where the national institute needs more detail. Statistics Netherlands states that the fifth level of SBI is specific to the Netherlands, and that the first four digits are, with a few exceptions, identical to NACE.

Destatis states that the German subclass is inserted as a fifth, deepest level for national interests and needs. The Statistical Office of Slovenia states that SKD 2025 has 678 subclasses at its lowest level, of which 46 are national subclasses. Each statement describes the same pattern from a different country: shared levels above, national detail below. The detail differs, because national needs differ.

What is shared, and what is national?

What is shared is the structure up to class level: 22 sections, 87 divisions, 287 groups and 651 classes (FIXED, as adopted), set by Commission Delegated Regulation (EU) 2023/137 of 10 October 2022 (FIXED). What is national is everything below class level, and any national title, note or breakdown that the institute publishes for its own country. A reader who compares statistics at class level or above can compare across countries, because the headings are shared. A reader who compares statistics at fifth level cannot compare across countries, because the headings are not shared. A fifth level heading in one country may have no equivalent in another, and a fifth level heading with a similar title in two countries may cover different activities, because each institute defines its own breakdown inside the class. The class is the comparable level. The fifth level is the national level.

Level	Shared or national	Comparable across countries
Section, division, group, class	Shared, European structure	Yes, at these levels
Fifth level, subclass	National, institute defined	No, national detail only
Keyword index, search tool	National, institute published	No, finding aid for one country

The table above states the comparison rule. It names no fifth level heading, because fifth level headings must be read in the institute material for the country concerned.

How do fifth levels handle the same class differently?

Fifth levels handle the same class differently in three ways. First, one country may divide a class while another leaves it whole, so that one country shows several subclasses and another shows one. CBS gives the example in its excerpt: a fifth level entry can repeat the class title where no finer breakdown is made. Second, two countries may divide the same class on different bases, so that their subclasses cut the class in different places and cannot be matched one to one. Third, a country may add a fifth level heading for a national activity that has no equivalent elsewhere, such as a national subclass listed by SURS for Slovenia. In each case, the class total can still be compared, by adding the subclasses back to the class, but the subclasses themselves cannot be compared. A reader who adds subclasses from two countries together, or who matches them by title, will produce a comparison that looks precise and is meaningless.

How should a fifth level code be cited?

A fifth level code should be cited with its country, its version, and its class stated beside it. A citation that gives only the five digits, without the country, is incomplete, because the same digits can mean different things in different countries, and can mean nothing at all in a country that does not divide that class. A citation that gives the fifth level without the class is also incomplete, because the fifth level gains its meaning from the class above it. The full citation therefore states the country, the classification name and version, the class, and the subclass, with the source being the institute that publishes the structure. A reader who finds a fifth level code in a dataset should check the dataset documentation for the country and version, and should not assume that the code follows the European structure beyond class level.

What do fifth levels not decide?

Fifth levels do not decide the code for any reader, and they do not decide tax, licensing, funding or collective agreement questions. They are finer statistical groupings, published by national institutes for national statistics. The entry for a specific unit is confirmed with the national institute or the business register that holds the record, in the country concerned. This site holds no register and decides no entry. A reader who treats a fifth level heading as a more specific legal status mistakes statistical depth for legal meaning. Depth in the hierarchy means finer grouping. It means nothing else, in any country.

Classes are shared and comparable, fifth levels are national and incomparable across borders, and every fifth level citation must carry its country, its version and its class beside it.