Is the 13th-month salary mandatory in France?

There is no national law requiring it. It is mandatory only where a collective bargaining agreement (convention collective), company agreement or your employment contract provides for it. Many French sectors include a 13ème mois, which is why it is so common.

How is the 13th month calculated?

The standard rule is one additional month of base salary per calendar year, equal to your gross monthly base pay. Some agreements base it on the average of the year's salaries or include a portion of fixed allowances; check your convention collective for the exact base.

How does pro-rating work if I join mid-year?

The entitlement is reduced in proportion to time worked. The tool multiplies one month of base salary by the days you worked divided by 365. Joining halfway through the year gives roughly half a 13th month.

Is the 13th month paid all at once?

It depends on the agreement. Some employers pay it as a lump sum in November or December, others split it across two instalments (for example June and December), and some smooth it across all twelve payslips. The annual total is the same.

Is the 13th month subject to social charges and tax?

Yes. In France the 13th month is treated as ordinary salary, so it is subject to the usual social contributions and income tax. This calculator shows the gross entitlement; your net will be lower after deductions.

France 13th Month Salary Calculator

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A France 13th-month salary calculator (calculateur du 13ème mois) that works out the extra month of pay many French employees receive each year, plus the pro-rated amount for anyone who joined or left part-way through the year. It is built around the common collective-agreement rule: one additional month of base salary per calendar year.

How it works

The classic 13ème mois equals one extra month of your gross base salary (salaire de base) for a full calendar year of work. For a complete year the calculation is simply your monthly base pay. For a partial year, the entitlement is scaled by the share of the year you were employed:

13th month = monthlyBaseSalary * (daysWorked / 365)

So an employee on a 3,000 EUR monthly base who works the whole year receives a 3,000 EUR 13th month. Someone who joined on 1 July and worked 184 days receives 3,000 * 184 / 365, roughly 1,512 EUR.

The 13th month is not a French statutory right — it exists only where a convention collective, company agreement or contract grants it. Where it applies, it is treated as ordinary salary for tax and social-contribution purposes.

Notes and example

Some agreements compute the 13th month on the average of the year’s monthly salaries rather than the latest base, or include certain fixed allowances. If your agreement does that, enter the relevant average as your monthly base. Variable elements like overtime, commission and one-off bonuses are normally excluded.

Worked example: monthly base 2,500 EUR, joined on 1 October, 92 days worked. The pro-rated 13th month is 2,500 * 92 / 365, about 630 EUR gross. Every figure here is gross and calculated locally in your browser.