Revised Payslip 2027: Understanding Mandatory vs. Optional Contributions for Employers

The revised payslip becomes mandatory on January 1, 2027, and its most confusing aspect is the distinction between “mandatory” and “optional” contributions: this does not mean what everyone thinks. This classification does not refer to the mandatory nature of the employee’s membership but rather to the method of calculating the Montant Net Social (MNS, Net Social Amount). Here’s how to accurately interpret the new layout.

This article is part of the Payroll Law: The Employer’s Guide.

Framework and Timeline

The layout of the revised payslip is set by the decree of January 31, 2023 (issued for the application of article R. 3243-2 of the Labour Code). The decree of August 11, 2025 makes the revised model mandatory on January 1, 2027, while the “adapted” model remains permissible until that date. The reference doctrine is the section on “Payslip” from the BOSS (Official Bulletin of Social Security) and the FAQ on “Montant net social” from the Ministry of Labour.

Key Point: The BOSS doctrine regarding the calculation of MNS underwent a reversal on November 14, 2023, effective January 1, 2024. This change affects the entire current treatment of complementary social protection contributions — previous references should be handled with caution.

The Criterion That Changes Everything

The layout distinguishes one block for “Mandatory Social Contributions and Contributions”, one block for “Optional Contributions”, and a section for “Reimbursements and Various Deductions.”

The designation of “mandatory/optional” does not depend on the obligation of membership (sector agreement, company agreement, unilateral decision). It is based on the category of the contribution in relation to the calculation of the MNS. Thus, there is a counterintuitive consequence that must be explained to payroll teams: mandatory insurance for executives will appear in the “optional” block.

Health Section: The Case of Dependents

The “Health” section, in the “mandatory” block, contains both the social security health contribution and the entirety of the complementary health insurance contribution (mutuelle) as defined by article L. 911-7 of the Social Security Code.

For dependents: whether the family coverage is mandatory or an optional plan chosen by the employee, the contribution is included in the “Health” section of the “mandatory” block. The criterion is material (the nature of