France's DSN: the monthly payroll declaration that replaced dozens of forms

Every employer in France files one déclaration sociale nominative (DSN) per establishment each month. The DSN is a single electronic file, generated from the payroll, that reports each employee's pay, social contributions and income-tax withholding to URSSAF, the pension and unemployment bodies and the tax authority at once. The monthly DSN is due on the 5th or the 15th of the following month, and separate event reports are due within five working days of a sick leave or an end of contract. Because every agency reads the same file, one wrong field is wrong for all of them.

What the déclaration sociale nominative reports, and who receives it

The DSN was created by the 2012 simplification law (Loi n° 2012-387) and is mandatory for every employer with staff (Social Security Code, CSS Art. L133-5-3). The DSN is filed per SIRET, the identifier of a single establishment, so a company with three sites files three DSNs a month.

Each file contains the month's payroll for every employee: identity, contract, gross and net pay, each contribution, and the income tax withheld under the prélèvement à la source (PAS, France's pay-as-you-earn withholding).

Employers submit the file on net-entreprises.fr, the official portal for social declarations (farm employers file through the MSA, the agricultural social security fund). The portal routes it to:

• URSSAF, which collects social security contributions;
• Agirc-Arrco, the complementary pension scheme;
• France Travail, for unemployment insurance and the end-of-contract certificate;
• the CPAM (local health insurance fund), which pays daily sick-leave allowances;
• the employer's health and prévoyance insurers (prévoyance covers death and disability);
• the DGFiP, the tax authority, which receives the PAS data and returns each employee's withholding rate.

By net-entreprises' count, the DSN has replaced close to 80 earlier formalities, including the URSSAF contribution slip (DUCS), the annual salary return (DADS-U) and the employer certificate for France Travail.

DSN deadlines: the 5th or the 15th of the following month

The deadline depends on headcount and on when salaries are paid (CSS Art. R133-14 and R243-6):

• 5th of the following month: employers with 50 or more employees who pay salaries in the same month as the work.
• 15th of the following month: all other employers, including a 50-plus employer that pays salaries in the following month.

On the deadline day the file must be filed by noon (metropolitan France). A deadline that falls on a weekend or public holiday is postponed to the next working day. The DSN is due every month, even when no salaries were paid, until the employer closes its URSSAF account. Contributions are normally paid by the same deadline.

Event reports: sick leave and end of contract within five working days

Events that affect an employee's benefits are reported in a separate DSN signalement d'événement (event report) within five working days (jours ouvrés: Monday to Friday, excluding public holidays) of the employer learning of them:

• Arrêt de travail (work stoppage: sick, maternity or paternity leave, or a work accident). The report starts the CPAM's calculation of daily allowances. Where the employer keeps paying the salary and claims the allowances back (subrogation), the report can be sent with the monthly DSN instead.
• Reprise anticipée (early return to work). This report is required only for a return before the date originally reported.
• Fin de contrat de travail unique (FCTU), the end-of-contract signalement. France Travail produces the employer certificate (attestation employeur) from this report; the former employee needs the certificate to claim unemployment benefit.

Every event must also appear in the next monthly DSN.

Correcting a DSN: annule et remplace, then regularisation

URSSAF runs automated checks on every file and returns an anomaly report, the compte rendu métier (CRM), within four hours of filing. The correction method depends on timing:

• Before the deadline: the employer files a DSN annule et remplace, which cancels the earlier file and replaces it in full. Net-entreprises accepts a replacement only until midnight (Paris time) on the day before the deadline.
• After that cut-off: the employer reports the correction in a regularisation block (adjustment lines for the earlier month) in the next monthly DSN.

Each March, URSSAF sends a reminder CRM listing the previous year's open anomalies, to be fixed by the May DSN. If any are still open after May, URSSAF can issue a DSN de substitution (since June 2026) and correct the data itself. The 2026 corrections cover the capped contribution base used for pension rights; URSSAF claims any contributions owing with late-payment surcharges.

Under the droit à l'erreur (right to make a mistake), no penalty or late-payment surcharge applies to an error when:

• the employer corrects the error at the next deadline and pays the extra contributions;
• the error is not repeated;
• either the penalty and surcharges would total less than one month's social security ceiling, or the extra payment is under 5% of the contributions first declared.

Penalties for a late, missing or inaccurate DSN

DSN penalties are set as a percentage of the monthly social security ceiling (plafond mensuel de la sécurité sociale, PMSS), which is fixed each year and is €4,005 in 2026 (CSS Art. R243-12 and R243-13):

• Late or missing DSN: 1.5% of the PMSS, about €60, per employee and per month or part-month of delay, based on the headcount in the last DSN filed. When the delay is five days or less, the total is capped at 150% of the PMSS (€6,007.50) per company, once per calendar year.
• An employee left out of the file: the same 1.5% per employee and per month.
• Under-declared pay that reduces contributions: 1% of the PMSS, about €40, per employee.
• Other omissions or errors: a third of the 1% rate, about €13 per employee.

The last two penalties do not apply if the employer corrects the data within 30 days. Late payment of contributions draws a separate surcharge of 5%, plus 0.2% per month or part-month (CSS Art. R243-16). A late PAS declaration costs 10% of the withholding due, with a minimum of €250 per declaration (General Tax Code, CGI Art. 1759-0 A).

A worked timeline: October payroll and an end of contract

Take a client company with 30 employees that pays October 2026 salaries on 30 October.

1. The normal deadline. With fewer than 50 employees, the October DSN is due on the 15th. In 2026, 15 November is a Sunday, so the deadline is noon on Monday 16 November.
2. An end of contract. One employee's fixed-term contract ends on Monday 2 November. The FCTU is due within five working days (3, 4, 5, 6 and 9 November), so by Monday 9 November.
3. The earlier monthly deadline. The contract ended between the 1st of the month and the 15th deadline, and the FCTU's five-day window closes before the 15th. In that case the October DSN is due by the FCTU deadline (CSS Art. R133-14 I): 9 November, a week earlier than usual. France Travail needs the October DSN on file to build the attestation from the monthly history.
4. The follow-up. The November DSN, due Tuesday 15 December, reports the employee's final pay and the end of contract.

If no contract had ended, an October DSN filed on Tuesday 17 November would be one day late. The penalty is 30 employees × 1.5% × €4,005 = €1,802.25. The amount is under the €6,007.50 cap for delays of five days or less, so it applies in full.

Summary

The DSN is France's single monthly payroll filing: one file per establishment, due by noon on the 5th or the 15th of the following month. Event reports are due within five working days, and an early-month contract end brings the previous month's DSN forward. Errors are fixed with annule et remplace before the deadline and by regularisation after it. A late DSN costs about €60 per employee per month in 2026.

Flux works with partners running French payroll, where the monthly and five-day deadlines have to be checked on every pay run.