How do the ATECO correspondence tables work?

The ATECO correspondence tables work by linking headings between versions, so that an old heading can be traced to its new heading or headings, and a new heading can be traced back to its old sources. Istat publishes a bidirectional correspondence table between ATECO 2025 and ATECO 2022, in Italian and English, and a separate operational reclassification table to support mass reclassification. The bidirectional table is the theoretical record of the link. The operational table is a practical tool for register holders where detailed information about the activity is missing.

The two tables serve different purposes, and a reader who uses one as if it were the other will misread the link. The theoretical table shows what the categories mean in relation to each other. The operational table shows what assignment a register holder makes where information is incomplete.

How is the bidirectional table read?

The bidirectional table is read in both directions. Forward, from ATECO 2022 to ATECO 2025, it shows where the activities in each old heading go. Backward, from ATECO 2025 to ATECO 2022, it shows where the activities in each new heading came from. One old heading with one new destination is a continuation or a rename. One old heading with several destinations is a split. Several old headings with one destination is a merge. Several old headings with several destinations is a rearrangement. The count of destinations is taken from the table, not from the titles. After the count, the explanatory note for each destination is read, because a destination that looks right in title can exclude the activity in its note. The table shows the link. The note shows the scope. Neither document determines the entry for a specific business.

Table	Purpose	Reading
Bidirectional correspondence table	Theoretical link between versions	Both directions, count destinations, read notes
Operational reclassification table	Support for mass reclassification without detailed information	Register holders, initial implementation phase
Explanatory notes	Content of each heading	Inclusions, exclusions, cross references

The table above separates the three documents by purpose. The operational table row follows Istat’s description: a tool made available to support mass reclassification operations, in the absence of detailed information describing the activity carried out, conceived mainly for the initial implementation phase by the bodies managing archives.

How does the operational table differ?

The operational table differs because it is designed for a different situation: a register holder must assign a new code to a large number of units, but holds no detailed description of what each unit does. In that situation, the theoretical table alone cannot decide the assignment, because a split heading offers more than one destination and the register holder has no information to choose between them. The operational table gives a default assignment for that situation, based on the information available to the register holders. Istat states that the operational table was developed with the chamber system for that purpose. A default assignment is not a theoretical link, and it is not a determination that the activity described in the default heading is the activity actually carried out. It is a starting point for the register, subject to confirmation and correction through the routes described in the confirmation guide in this cluster. A reader who treats an operational assignment as a theoretical link will overstate what the table proves.

What are the limits of both tables?

Both tables share the limits of any correspondence table. They are written for categories, not for individual units. Where a table says one to many, many to one, or many to many, the mapping is not a 1:1 guarantee. The legislation only applies to statistical purposes, as the EUR-Lex summary states. A table row does not decide tax, licensing, funding or collective agreement questions. A table row also does not show proportions: where an old heading splits, the table does not state how many units go to each destination, and where headings merge, the table does not state the share each source contributes. Proportions belong to published statistics, not to the table. Published comparable series, not inferences from the row count, are where a reader needing proportions should look.

Where are the tables confirmed?

The tables are confirmed on the Istat website, in the dedicated ATECO section, where Istat states that all official documentation is available. Istat or the business register holding the record confirms the entry for a specific business. This site holds no register and decides no entry. A reader who finds a correspondence table on another site should check it against the Istat section, and should state the edition and the direction read when citing a row. A row without an edition, and without a statement of direction, is an incomplete citation.

The bidirectional table links headings in theory, the operational table supports mass assignment where information is missing, and the notes for each destination state the scope that the table alone cannot show. ”