Health Contribution Calculation Base: Avoiding Risks with URSSAF
When your collective agreement refers to the “fixed gross base salary,” the health contribution is calculated on the contractual salary — and definitely not on the reduced remuneration due to absence. Prorating this base means under-reporting… and exposing yourself to a potential URSSAF audit. Here is the rule and the method for setting it up.
This article is part of the Payroll Law: The Employer’s Guide.
The base to retain: the contractual fixed gross base salary
When the collective text refers to the “fixed gross base salary” (a common formulation, for example in certain collective bargaining agreements for service providers), the health contribution is calculated on the contractual base salary, regardless of monthly variations.
Example: for a contractual base salary of €4,000 gross, the contribution is calculated on €4,000, even if an absence has reduced the payment to €3,300 (subject to the collective ceiling, often expressed as a percentage of the A tranche of the monthly social security ceiling).
Why? The term “fixed” excludes any variations: bonuses, surcharges, overtime or additional hours, and temporary variations due to absence. The text explicitly excludes these extras (“excluding bonuses, excluding surcharges…”). A strict interpretation applies: if the social partners intended a prorated base, they would have referred to “the remuneration subject to contributions” or a base “prorated in case of absence.” Otherwise, one does not replace the fixed gross base salary with the social base for the month.
The URSSAF risk of a reduced base
Retaining €3,300 instead of €4,000 results in under-reporting of both employee and employer contributions to the scheme. However, the employer contribution to funding supplementary health insurance constitutes a benefit, a fraction of which is reintegrated into the CSG/CRDS base. A reduced contribution could therefore lead to a social shortfall — and increase the risk of adjustment in the event of an audit. Retaining the referenced contractual base secures the social treatment.
Caution: check the insurer’s notice or the collective contract — a clause may modify the calculation in the event of suspension of the contract. In the absence of contrary stipulation, the calculation based on the non-prorated contractual base salary is the most robust option.
Setting up the bases: CCN by CCN
Do not look for a “standard” unique base. The texts might be hybrid (the same article targeting “gross salaries subject to contributions” while excluding overtime, bonuses, allowances, benefits in kind, and professional expenses).
Method: define a reference base (PMSS, gross subject to contributions, or base salary), then apply inclusion/exclusion rules by payroll category, according to the collective agreement, the implementation act, and the insurer’s contract.
Frequently Asked Questions
Should we prorate in case of absence? No, the base = contractual base salary.
Why is there a URSSAF risk? Under-reporting → impact on CSG/CRDS → potential adjustment.
Is there a single base for all CCNs? No: reference base + rules by category.