What is double reporting in the transition?

Double reporting means sending statistics broken down by NACE Rev. 2 in parallel with statistics broken down by NACE Rev. 2.1, for a certain period. Eurostat states on its transition page 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 certain European business statistics, Eurostat states that backcasting and double reporting requirements are set out in Commission Implementing Regulation (EU) 2024/1840. Double reporting is a transition device.

It is not a permanent second series, and it does not create two different economies.

Why send the same statistics twice?

Sending both versions in parallel lets users compare the old and new breakdowns for the same reference period, and lets producers check that the changeover has been applied consistently. A single version switch would leave a reader with no overlap period in which to see the effect of the classification change. With double reporting, the same reference period appears twice, once on each basis, and the difference between the two presentations is the classification effect, visible in the data itself. That visibility is valuable precisely where classes split or merge, because the aggregate for a section may stay similar while the divisions and classes inside it move. The parallel period also gives users time to update their own tables, models and code lists, without being forced to switch on a single publication date.

How does double reporting differ from backcasting?

Double reporting and backcasting are related, but they work in opposite directions in time. Double reporting covers current or recent reference periods, presented on both bases at the same time. Backcasting covers earlier reference periods, restated on the new basis after the event. Eurostat describes both on its transition page, and states that plans for backcasting and double reporting are being established with its partners in the European Statistical System. For certain European business statistics, both requirements are set out in Commission Implementing Regulation (EU) 2024/1840. A reader should not confuse the two. A double reported figure for a recent period is a current compilation on two bases. A backcast figure for an earlier period is a reformulation, produced by a stated method, and its method note matters in a way that a double reported figure’s note does not.

Device	Periods covered	Basis shown
Double reporting	Current or recent periods, in parallel	NACE Rev. 2 and NACE Rev. 2.1 together
Backcasting	Earlier periods, restated	NACE Rev. 2.1, reformulated from the old basis
Single version publication	Periods after the changeover	NACE Rev. 2.1 only

The table shows the three states a series can be in during and after the transition. A dataset in the first state will have two values for the same reference period. That is expected, and it is not an error or a contradiction. The values differ because the classification differs.

How long does double reporting last, and where is the period set?

The period is set domain by domain, in the instrument for that domain. Eurostat states that double reporting will apply for a certain period, without fixing a single period for all domains in the text consulted. For certain European business statistics, the requirements are set out in Commission Implementing Regulation (EU) 2024/1840. No single double reporting end date was verified in the pages consulted for this guide, and no date published as checked on 28 October 2026 is asserted for double reporting in general. A reader who needs the period for a domain should open the domain instrument and the dataset metadata, and record the period with the FIXED or EXPECTED label that the text supports. The general range, from 1 January 2025 to 1 January 2031 (FIXED range), frames the transition, but it does not fix the double reporting period for any domain.

How is a double reported dataset cited?

A double reported dataset must be cited with the version. A citation that gives a figure without stating whether it is the NACE Rev. 2 value or the NACE Rev. 2.1 value is incomplete, because the same reference period has two values. The citation should record the dataset, the reference period, the NACE version, and the publication or transmission date. Where the two versions differ, the difference should be described as a classification effect, and the correspondence table should be consulted for the classes that moved. Where a class split, the table shows a one to many mapping, which does not by itself pick the new class for a specific unit. The explanatory note for each new class states what it includes and excludes, and it remains the record of meaning for the new breakdown.

What does double reporting not do?

Double reporting does not reclassify individual businesses twice, and it does not create two entries for a unit in a business register. It presents aggregate statistics on two bases. The entry for a specific unit is held in the business register, and it is confirmed with the national statistical institute or the register that holds the record. Double reporting also does not decide tax, licensing, funding or collective agreement questions. The EUR-Lex summary states the legislation applies only to the use of the classification for statistical purposes. The parallel presentation is a statistical device, and its limits are the limits of the classification itself.

Record the version with every figure from a parallel dataset, check the correspondence table for the classes that moved, and confirm a single entry with the institute or register that holds it.