NAF Code, Collective Agreement, AT/MP: the Real Impacts for Your Business in 2026

Updated 25 May 2026 — The NAF code (Nomenclature d'activités française, revision 2) is frequently dismissed as a mere administrative formality. That is a costly misreading. The code, assigned by INSEE at the time of registration, directly determines the collective bargaining agreement (convention collective) that applies to your workforce, the AT/MP contribution rate (accidents du travail et maladies professionnelles — workplace accident and occupational disease levy) calculated by URSSAF, your OPCO affiliation (the operator financing vocational training and apprenticeships), and certain CFE exemptions. A code that is wrong or not updated following a change in activity can trigger several thousand euros of retrospective adjustments.

Quick answer (45 words): the NAF code is a statistical identifier assigned by INSEE. It is not merely administrative — it determines the applicable collective agreement, the URSSAF AT/MP workplace-accident contribution rate, your OPCO affiliation, certain CFE exemptions, and the correct monthly DSN payroll declaration settings.

The NAF code (also referred to as the APE code, for Activité Principale Exercée — principal activity carried on) is a four-digit code followed by a letter that statistically identifies a company's principal activity. It appears on the Kbis company extract, payslips (article R. 3243-1 of the Code du travail), the DSN monthly social declaration, CFE-CVAE tax filings, and the annual liasse fiscale (tax return pack).

It coexists with two other classification systems that business owners frequently conflate:

These three systems coexist but serve entirely different purposes. Confusing the ROME with the PCS-ESE in the DSN is a common software configuration error. The ROME carries no mandatory weight in social declarations.

INSEE assigns the NAF code at the time of registration in the Registre national des entreprises (RNE), based on the activity description declared to the relevant Centre de Formalités des Entreprises (CFE) — CCI, CMA, or URSSAF depending on the legal form — or, since January 2023, via the single online gateway at formalites.entreprises.gouv.fr.

If the company's actual activity changes significantly, the directors must request an update of the NAF code within 30 days of the change (to verify: exact deadline depending on legal form and applicable text). The process is free of charge and is handled via the formalites.entreprises.gouv.fr gateway or directly with INSEE via the Sirene portal. Processing typically takes 4 to 8 weeks.

Point of vigilance: INSEE's attribution of the NAF code is based on the initial declaration. If your activity has evolved without any update, it is your responsibility to take the initiative.

The applicable collective agreement is determined by the actual principal activity of the company, in accordance with article L. 2261-2 of the Code du travail. The NAF code is a primary indicator, but it is not the exclusive legal basis.

Where the NAF code assigned by INSEE diverges from the company's actual activity, the actual activity prevails. However, that divergence must be documented: management reports, representative contracts, and a breakdown of turnover by activity.

Practical consequence: an incorrect collective agreement leads to errors in minimum pay scales, job classifications, additional leave entitlements, seniority bonuses, and disciplinary procedures. In the event of a URSSAF audit or Labour Inspectorate visit, applying an inappropriate collective agreement is grounds for a formal reassessment.

URSSAF calculates the AT/MP rate from the risk code linked to the company's NAF code. This rate is individual for companies with more than 150 employees (actual rate), mixed for those with 20 to 149 employees, and collective (sector-wide) for companies with fewer than 20 employees.

For 2026, the indicative ranges observed are as follows (to verify against your URSSAF notification and the official website):

These figures are indicative ranges only. The exact rate notified by URSSAF at the beginning of each year is the binding figure. An inappropriate NAF code can result in a collective rate that is incorrectly low — exposing the company to a back-payment demand following a workplace incident — or incorrectly high, representing a significant over-payment of contributions.

The NAF code determines the OPCO affiliation — the vocational training operator that finances professional development and apprenticeships. The principal OPCOs in 2026 (subject to any restructuring) are:

• Atlas: financial services, consulting, audit, IT management
• AKTO: hospitality and catering, cleaning services, personal services
• Constructys: construction, residential property development
• OPCO EP: vocational training, private education
• Ocapiat: agriculture, cooperatives, food processing industries

Incorrect OPCO affiliation means training-funding applications are rejected or misdirected, and apprenticeship levy payments are sent to the wrong operator.

The risks fall into three categories.

Social risk: URSSAF back-payment for incorrect AT/MP rate or incorrect collective agreement application, plus late-payment interest. The reassessment can cover the three most recent years.

Fiscal risk: loss of a CFE exemption conditional on the correct NAF code (rural revitalisation zones, enterprise zones, trades registered on the artisan register). A craft business with the wrong code can miss an exemption worth several hundred to several thousand euros per year.

Documentary risk: inconsistency between the NAF code, the collective agreement actually applied, and the payslips. During an audit, this inconsistency acts as a red flag that broadens the scope of the inspection.

1. Identify the target code: consult the NAF rev. 2 classification on insee.fr and document the change of activity (purchase orders, representative invoices and contracts).
2. File the modification via the formalites.entreprises.gouv.fr gateway (since January 2023, this single gateway replaces the individual CFEs). Attach evidence of the actual activity.
3. Notify the downstream impacts: contact URSSAF to update the AT/MP rate, verify the OPCO affiliation, and update your payroll software (NAF code on payslips and DSN).
4. Date the change: the effect runs from the date of the actual change of activity, not from the date of the INSEE registration.
5. Document the change to pre-empt any future audit.

Our view — Hayot Expertise: before any significant diversification of activity, we recommend confirming with your accountant (1) the target NAF code, (2) the impact on the collective agreement and the AT/MP rate, and (3) the effective date and declaration procedure. This preparation avoids 3 to 6 months of retrospective URSSAF regularisations.

A management consultancy (code 7022Z, Syntec collective agreement, OPCO Atlas, AT/MP rate 0.65 %) builds a continuous professional training arm that represents 60 % of its turnover by the end of financial year N. The NAF code appropriate to the new principal activity becomes 8559A (continuing education for adults and young adults), with affiliation transferring to OPCO EP and a different collective agreement (the vocational training sector agreement).

Without an update, payslips continue to reference the Syntec collective agreement, the minimum pay scales applied are potentially incorrect for trainers, and apprenticeship-levy funding is processed by the wrong OPCO. If a URSSAF reassessment follows two years later, it covers all financial years that have not yet prescribed.

The point most often overlooked by business owners: the NAF code assigned at incorporation reflects the declared activity, not necessarily the activity that developed. It is common for a five-year-old company's actual activity to bear little resemblance to its original NAF code. This gap usually goes unnoticed until the first URSSAF audit or until a training-funding application is rejected by the OPCO.

Beyond the NAF code itself, the coherence of your monthly DSN and payroll software settings determines the operational quality of your compliance file. Three checkpoints to review each quarter:

• PCS-ESE code per employee: this must be distinguished from the company's NAF code. An incorrect PCS-ESE assignment can generate inconsistencies in URSSAF, France Travail and pension-fund declarations.
• Collective agreement entered in the DSN: must match the one actually applied. A collective agreement declared but not applied — or vice versa — is a frequent basis for URSSAF reassessment.
• AT/MP rate applied: check it each year against the URSSAF notification received at the start of the year. Even a small drift over 12 months can represent several thousand euros for a medium-sized business.

This cross-check — NAF code / DSN / payroll — is part of the preventive audits we carry out systematically on business-acquisition files or whenever a client migrates to a new accounting software system.

We analyse your actual activity, the applicable collective agreement, the optimal AT/MP rate and DSN coherence — before any costly URSSAF regularisation becomes necessary.

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This article provides general information. AT/MP rates, NAF codes and collective agreement affiliations change over time. Verify the parameters specific to your situation with your accountant.

Updated 25 May 2026. Sources: INSEE (NAF rev. 2), Code du travail art. L. 2261-2 and R. 3243-1, URSSAF (AT/MP rates), BOFiP (CFE-CVAE), formalites.entreprises.gouv.fr.