Introduction: Understanding Taxable Income in Payroll

The taxable income is one of the most strategic elements of the payslip. It determines the basis upon which the employee will be taxed for income tax, and it is the data transmitted to the tax authorities via the DSN (Déclaration Sociale Nominative). However, its calculation is often poorly understood, even by experienced payroll professionals.

In 2025, several parameters influence the calculation of taxable income: the non-deductible CSG, the CRDS, the employer’s share of complementary social protection (PSC), exempt overtime, or the 1.75% deduction on the CSG/CRDS base. This comprehensive guide will walk you through mastering this essential calculation, relying on references from the BOSS (Bulletin Officiel de la Sécurité Sociale) available at boss.gouv.fr.

What is Taxable Income?

Definition and Role on the Payslip

The taxable income, sometimes referred to as net fiscal, refers to the amount of salary income subject to income tax. It is mandatory to appear on the payslip since the reform aimed at clarifying payslips. It should not be confused with the net payable before tax or the montant net social (MNS).

Specifically, taxable income is calculated using the following formula:

Taxable Income = Gross Salary – Deductible Employee Contributions + Non-Deductible CSG (2.40%) + CRDS (0.50%) + Employer’s Share of Taxable PSC

It is crucial to distinguish among these three concepts:

Net Payable Before Tax: This is the amount that the employee actually receives in their bank account, before withholding tax (PAS).
Taxable Income: This is the basis for calculating income tax. It is higher than the net payable because it reintegrates the non-deductible CSG and the CRDS.
Montant Net Social (MNS): Introduced in 2023, it serves as a reference for social benefits (RSA, activity bonus). It differs from taxable income because it does not include the same adjustments.

Components of the Calculation of Taxable Income

Gross Salary: Starting Point

The calculation of taxable income starts from the gross salary, which includes all remuneration elements: base salary, bonuses, benefits in kind, overtime, and various allowances subject to contributions. For an employee with a gross monthly salary of €3,200, this amount serves as the starting point.

Deductible Employee Contributions

From the gross salary, all mandatory employee contributions deductible from income tax are deducted. This includes:

Health, old-age, and unemployment insurance contributions;
Contributions to complementary retirement plans (Agirc-Arrco);
The deductible CSG at a rate of 6.80%;
Employee contributions to welfare and mutual insurance (employee share).

Note: The deductible CSG (6.80%) is indeed subtracted from the gross salary to determine the taxable income, but the non-deductible CSG (2.40%) and the CRDS (0.50%) are not.

Non-Deductible CSG (2.40%) and CRDS (0.50%)

These two contributions, although deducted on the payslip, are not deductible from income tax. Therefore, they must be reintegrated into the taxable income. In practice, they increase the employee’s tax base.

In 2025, the applicable rates are:

Total CSG: 9.20%, of which 6.80% is deductible and 2.40% is non-deductible;
CRDS: 0.50%, fully non-deductible.

These contributions are applied to 98.25% of the gross salary (after applying the 1.75% deduction), up to 4 annual social security ceilings (4 PASS), i.e., €185,472 in 2025. Beyond this threshold, the CSG and CRDS apply to 100% of the remuneration, without deduction.

The 1.75% Deduction on the CSG/CRDS Base

According to the BOSS, a flat-rate deduction of 1.75% is applied to income from work for calculating the CSG and CRDS base. This deduction represents professional expenses and applies only to the portion of remuneration that is less than or equal to 4 PASS (i.e., €185,472 annually in 2025, or €15,456 monthly).

Example: For a gross salary of €3,200, the CSG/CRDS base is: €3,200 × 98.25% = €3,144.

The employer’s contribution to financing mandatory mutual insurance and welfare constitutes a taxable benefit for the employee. Although it is not subject to social security contributions (within certain limits), it must be reintegrated into taxable income.

In practice, if the employer pays €60 per month for mutual insurance and €25 per month for welfare, totaling €85, this amount is added to the employee’s taxable income.

BOSS Reference: the employer’s share of PSC is subject to CSG/CRDS but excluded from the social security contribution base within the limits set by Article L.242-1 of the French Social Security Code.

Complete Example of Calculating Taxable Income in 2025

Example Data

Let’s take the case of an executive employee with the following details:

Monthly gross salary: €3,200
Total employee contributions (excluding CSG/CRDS): €580
Deductible CSG (6.80% × 98.25% × 3,200): €213.79
Non-deductible CSG (2.40% × 98.25% × 3,200): €75.46
CRDS (0.50% × 98.25% × 3,200): €15.72
Employer’s share of mutual insurance: €60
Employer’s share of welfare: €25

Step-by-Step Calculation

Step 1: Gross salary = 3,200 €

Step 2: Deduction of deductible employee contributions = 3,200 – 580 – 213.79 = €2,406.21

Step 3: Reintegration of non-deductible CSG = 2,406.21 + 75.46 = €2,481.67

Step 4: Reintegration of CRDS = 2,481.67 + 15.72 = €2,497.39

Step 5: Reintegration of employer’s share of PSC = 2,497.39 + 85 = €2,582.39

The monthly taxable income is therefore €2,582.39.

Treatment of Exempt Overtime

The Principle of Tax Exemption

Since the reactivated TEPA law, overtime (and complementary hours for part-time workers) benefits from an income tax exemption up to €7,500 net per year. This ceiling is assessed on the calendar year.

In practice, the remuneration for exempt overtime is subtracted from the taxable income, thereby reducing the employee’s tax base.

Impact on the Calculation of Taxable Income

If an employee performs exempt overtime with net taxable remuneration amounting to €250 in the month, and they have not yet reached the annual ceiling of €7,500, this amount will be deducted from the taxable income.

Example: Let’s take our employee with a taxable income of €2,582.39. If they have performed exempt overtime of €250, their taxable income becomes: 2,582.39 – 250 = €2,332.39.

The employer must keep an annual cumulative record of exempt overtime to ensure compliance with the €7,500 ceiling. Beyond this limit, the remuneration for overtime becomes taxable again.

Meal Vouchers and Taxable Income

Exempt Employer Contribution and Limits

The employer’s contribution to meal vouchers is exempt from income tax within certain limits. In 2025, the employer’s share is exempt if it meets the following conditions:

It represents between 50% and 60% of the value of the voucher;
It does not exceed €7.26 per voucher (2025 limit).

If the employer’s contribution respects these limits, it does not have to be reintegrated into taxable income. However, any excess must be added to the employee’s taxable income.

The Link Between Taxable Income and DSN

Transmission to the Tax Authorities

Taxable income is transmitted monthly to the tax authorities via the DSN. This information allows the calculation of the withholding tax (PAS). The PAS rate, whether personalized or neutral, directly applies to the taxable income to determine the amount of tax withheld each month.

Errors in calculating taxable income have direct consequences:

On the amount of PAS withheld monthly;
On the employee’s pre-filled income tax return;
On potential URSSAF or tax audits.

Verification and Regularization

In case of an error detected in the taxable income, the employer must proceed with regularization in DSN. It is recommended to systematically check the consistency between the taxable income displayed on the payslip and that transmitted in the DSN, especially in cases of:

Salary back-payments;
Contribution regularizations;
Change of circumstances (part-time, sick leave, etc.).

Special Cases Affecting Taxable Income

The IJSS paid by the CPAM in case of illness are taxable (except in exceptions related to long-term illness). When the employer practices subrogation, the IJSS are integrated into the payslip and must appear in the taxable income.

Benefits in Kind

Benefits in kind (company vehicles, housing, meals, IT benefits) are included in the gross salary and thus in the taxable income. Their assessment can be either flat-rate or actual, depending on the rules of the BOSS.

Employee Savings

Payments related to profit-sharing or participation are not taxable if they are allocated to a savings plan (PEE, collective PER). However, if the employee opts for immediate payment, these amounts are added to the taxable income.

Termination Indemnities

Termination indemnities are exempt from income tax within certain limits (the highest between the legal or contractual indemnity, 50% of the total indemnity, or 2 PASS). Beyond this, the excess amount is taxable and included in the taxable income.

Best Practices for Payroll Managers

Monthly Control Points

To ensure the accuracy of taxable income, it is recommended to implement the following checks:

Verify the calculation formula in the payroll software, especially after updates;
Check the reintegration of the employer’s share of PSC, particularly during changes in mutual or welfare plans;
Monitor the cumulative exempt overtime to detect crossing the €7,500 threshold;
Compare the taxable income on the payslip with the corresponding section in the DSN;
Archive payslips and supporting documents for facilitating possible audits.

Common Mistakes to Avoid

The main mistakes encountered in practice are:

Failure to reintegrate the employer’s share of PSC;
Confusion between deductible and non-deductible CSG;
Not respecting the ceiling of €7,500 for exempt overtime;
Applying the 1.75% deduction beyond 4 PASS;
Confusion between taxable income and montant net social.

FAQ: Taxable Income in Payroll

The montant net social (MNS) serves as a reference for social benefits (RSA, activity bonus), while taxable income serves as the basis for calculating income tax. The two amounts differ primarily in the treatment of non-deductible CSG, CRDS, and certain remuneration elements. The MNS does not reintegrate the same elements as taxable income.

Does the deductible CSG reduce taxable income?

Yes. The deductible CSG (6.80%) is subtracted from the gross salary for calculating taxable income. Conversely, the non-deductible CSG (2.40%) and CRDS (0.50%) are not deducted, thus increasing the taxable income compared to net payable.

How to treat exempt overtime in taxable income?

The net remuneration for overtime is deducted from taxable income up to €7,500 net per year. The employer must maintain an annual cumulative record to ensure compliance with this ceiling. Beyond this, overtime becomes taxable again.

Yes. The employer’s contribution to financing mandatory mutual insurance (and welfare, if applicable) constitutes a taxable benefit. It must be reintegrated into the employee’s taxable income, even if exempt from social contributions within certain limits.

How to verify taxable income on the payslip?

You can reconstruct the taxable income starting from the gross salary, deducting the deductible employee contributions (including deductible CSG), and then adding the non-deductible CSG, CRDS, and the employer’s share of PSC. Compare the result with the « taxable income » or « cumulative taxable income » line on the payslip. If there is a discrepancy, check the treatment of exempt overtime and benefits in kind.

How to Calculate Taxable Income on Payroll in 2025: A Comprehensive Guide