What does a new code in an old listing mean?

A new code in an old listing usually means that the listing was updated in its codes after its main content was compiled, or that the code was restated on the new basis through backcasting or double reporting, and the record date must be checked before the code is used. The listing date is not the version date of the code. The version is stated in the metadata, the revision note, or the register record, and it must be found there.

How does a new code appear in an old record?

A new code appears in an old record in three ways, and each should be recognised, because each calls for a different citation. First, the record was updated: a listing or a register extract was refreshed with new codes, while the surrounding content, such as the company description or the report text, was left unchanged. The code is new, and the surrounding content is old, and the citation should state the update date for the code. Second, the series was backcast: earlier statistics were restated on the NACE Rev. 2.1 basis, so that a historical series can be read without a break, as Eurostat describes on its transition page. The figures are restated, and the method note states the backcasting method used. Third, the series was double reported: the same reference period was sent on both bases in parallel, as Eurostat also describes, so that the same period appears twice, once on each version. The code is new in one presentation and old in the other, and the citation must state which presentation is quoted.

How is a backcast code recognised?

A backcast code is recognised by its method note. The Eurostat backcasting manual, in its 2025 edition, provides guidance to producers of official statistics that need to produce consistent historical time series for an updated classification, and it gives an overview of methods for reformulating statistics presented according to the old version in terms of the new version. A dataset that has been backcast should state, in its metadata or methodology, that it was backcast, which method was used, and whether the units were double coded under both versions. A reader who sees a new code in a series for an earlier reference period should look for that note, and should record it with the figure. A series without a method note, showing new codes for old periods, has not been shown to be backcast, and it should be treated as unchecked, until the publisher confirms the method.

How is a double reported code recognised?

A double reported code is recognised by the presence of two values for the same reference period, one on each version. Eurostat states that, for some statistics, there will be double reporting, with countries sending statistics broken down by NACE Rev. 2 in parallel to statistics broken down by NACE Rev. 2.1 for a certain period. A dataset in that state will show the same period twice, and the difference between the two presentations is the classification effect. A reader should record which presentation is quoted, and should not average the two, or choose between them without stating the choice. The general range, from 1 January 2025 to 1 January 2031 (FIXED range), frames the transition, but the double reporting period for a domain is set in the domain instrument, and no single double reporting end date is asserted here.

Presentation	What is shown	Citation needs
Updated listing	New code, old surrounding content	Update date for the code, version
Backcast series	Earlier periods restated on the new basis	Method note, version, reference period
Double reported series	Same period on both bases	Which presentation is quoted, version
Single version, old record	Old code, old period	Version and reference period, as stated

The table shows the four presentations a reader can meet, and the citation each one needs. A new code in an old listing belongs in one of the first three rows, and the row should be identified before the code is quoted.

What does a new code in an old listing not prove?

A new code in an old listing does not prove that the business changed its activities, that the listing was republished, or that the old record was wrong. It proves that the code shown is on the new basis, for one of the reasons above, and that the surrounding content may be older than the code. The Central Statistics Office states that its outputs will begin to be published using NACE Rev. 2.1 from January 2026 onwards (FIXED, as stated by the Central Statistics Office), on a gradual basis, and a listing that draws on CSO outputs during that period can show new codes in otherwise older content, as outputs move one by one.

Where is a new code in an old listing checked?

A new code in an old listing is checked in the register that holds the record, for the entry currently held, and in the dataset metadata, for the version and the method. The meaning of the new category is checked in the explanatory notes for the new version, and the move from the old category in the correspondence table, with the mapping type recorded. The entry for a specific business is confirmed in the register, not in the listing. A code that cannot be placed in one of the four presentations in the table should be recorded as unplaced, with the date of the check, rather than being assigned to a presentation by assumption.

Identify the presentation, record the version and the method note, and confirm the entry in the register that holds it.