Updated Payroll Slip 2027: What Employers Must Understand About Mandatory vs. Optional Contributions
The updated payroll slip becomes mandatory on January 1, 2027, and its most misleading novelty is the distinction between “mandatory” and “optional” contributions: this does not mean what everyone thinks. This qualification does not refer to the compulsory nature of employee membership but rather to the method of calculating the Montant Net Social (MNS, Net Social Amount). Here’s how to correctly interpret the new template.
This article is part of the Payroll Law: The Employer’s Guide.
The Framework and the Timeline
The template for the updated payroll slip is set by the decree of January 31, 2023 (issued for the application of Article R. 3243-2 of the French Labour Code). The decree of August 11, 2025 makes the updated model mandatory from January 1, 2027, with the “adapted” model allowed until that date. The reference doctrine is the section “Payroll Slip” of 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 MNS calculation underwent a reversal on November 14, 2023, coming into effect on January 1, 2024. This affects all current treatment of complementary social protection contributions — previous references should be handled cautiously.
The Criteria That Changes Everything
The template distinguishes between a block for “Mandatory Social Contributions”, a block for “Optional Contributions”, and a section for “Reimbursements and Various Deductions.”
The classification of “mandatory / optional” does not depend on the compulsory nature of membership (branch agreement, company agreement, unilateral decision). It depends on the category of contribution concerning the calculation of the MNS. Hence, a confusing consequence to explain to payroll teams: a mandatory insurance plan for executives will appear in the “optional” block.
“Health” Section: The Case of Dependents
The “Health” section in the “mandatory” block includes the social security health contribution and the entirety of the complementary health contribution (mutuelle) under Article L. 911-7 of the French Social Security Code.
For dependents: whether the family coverage is mandatory or an optional plan subscribed by the employee, the contribution appears in the “Health” section of the “mandatory” block. The criterion is material (the nature as “health costs”), not formal (the compulsory nature of membership).
The “Optional” Block: Insurance and Additional Retirement
This block includes all guarantees other than health costs: insurance (disability, incapacity, death) and additional retirement — regardless of their mandatory nature. The insurance for executives (Article 7 of the ANI of November 17, 2017, employer contribution of at least 1.50% within the ceiling limit) is also included here.
Since January 1, 2024, the MNS criterion is the collective nature according to Article L. 911-1 CSS: contributions financing a collective scheme, even with optional membership, are deducted from the MNS.
What Employers Must Do
To secure this classification, a contract-by-contract review is necessary (collective nature, valid founding act, scope of beneficiaries) — along with communication to payroll teams and employees; otherwise, the “optional” block will lead to misunderstandings among executives.
Frequently Asked Questions
When is it mandatory? On January 1, 2027.
“Mandatory/Optional” = membership? No, it pertains to the calculation of the MNS.
Dependents for health costs? They are included in the “mandatory” block, Health section.