The scale applies to your income divided, not to your income
The quotient familial is the most distinctive feature of French income tax and has no equivalent in Spain or Ireland. The scale is not applied to what you earn: it is applied to what you earn divided into «parts», and the result is multiplied back by that same number.
Parts are counted like this: a single person is 1 part, a couple is 2, each of the first two children adds half a part, and from the third onwards each child adds a whole one. Because dividing income before applying a progressive scale drops it into lower brackets, the mechanism cuts a family's average rate considerably.
Which is exactly why it is CAPPED: the tax advantage each additional half-part provides cannot exceed 1,807 €. Without that limit, the quotient familial would benefit high earners far more than low ones, the opposite of what it is meant to do.
The décote, which can wipe out the tax entirely
Below a certain amount of tax, France does not apply a tax-free allowance: it applies a rebate with a formula of its own. The décote subtracts from your tax an amount that depends on the tax itself, and on the lowest incomes it cancels it completely.
Because the rebate shrinks as the tax rises, the band where the décote is active carries a real marginal rate noticeably higher than the nominal one in the table. It is the same effect as Portugal's minimum of existence or the Dutch credit taper: what is withdrawn as your salary rises is real money.
You pay the whole CSG, but only part of it is deductible
This is the third French trap, and the one that most confuses people reading a payslip. Of the 9.20 points of CSG you pay, only 6.80 are deductible from income tax. The other 2.40, plus the CRDS, are paid on income that is ALSO taxed.
Put another way: there is a slice of your salary you pay on twice. It is nobody's mistake and no accounting quirk, it is how the CSG was designed when it was created, and it is one of the reasons the real French marginal rate runs higher than the scale suggests.
Where these figures come from
The scale is the 2026 one, applied to 2025 earnings — France settles the following year — and the 2026 Sécurité sociale ceiling is 48,060 € a year. The checkpoints for all three mechanisms — quotient familial, décote and the deductible split of the CSG — are frozen in the test suite and verified on every deployment.
What this calculator does not include
- APEC and the other contributions specific to cadres.
- The extra half-part for a parent isolé and its own separate cap.
- Company mutuelle, prévoyance and collective agreement arrangements.
- That the prélèvement à la source uses a provisional rate which may differ from the final tax. What is computed here is the tax for the year, not the month's withholding.
Last updated: October 8, 2026