Module 19 min873 wordsFree — no account
From gross pay to the figure the tax office actually taxes
The explanation, in the order it is meant to be read · 22 sections · 737 words · 4 min
Nadia takes home 2 700 € a month, or 32 400 € across the year. She budgets for tax on all of it. The tax office taxes 29 160 € instead, and bills her 1 909 €. The missing 3 240 € is not a favour anyone granted her — it is an automatic deduction nobody explained. This module tracks every euro between the payslip and the taxable base.
What you will be able to do
- Tell apart net pay received, taxable net pay and net taxable income — three different figures on one payslip.
- Place each of your income streams in its category, because the calculation follows the category.
- Understand why withholding at source does not replace filing a return.
One payslip, three different totals
Net pay received is what reaches the bank account. Taxable net pay, printed further down the payslip, is higher: it adds back the share of social contributions that the law refuses to treat as deductible. This second figure is the one your employer reports.
A flat 10 % allowance then comes off that annual figure, meant to cover work expenses: commuting, meals, professional reading. It applies automatically, it is capped, and you may swap it for your documented actual expenses if they come out higher.
Definition
Net taxable income — What remains after the 10 % allowance or actual expenses have been applied, category by category. This figure, not the salary you received, is what enters the progressive scale.
The order matters: deduct first, apply the scale second. Reversing the two inflates the bill by several hundred euros and wrecks any attempt to plan cash flow for the year ahead.
Each income stream follows its own rules
French tax law does not recognise a single thing called income. It recognises categories, each with its own deductions. Filing a payment under the wrong one does not merely misplace a line: it applies the wrong calculation entirely.
- Salaries and wages: 10 % flat allowance, or documented actual expenses.
- Rental income: micro scheme with a flat allowance, or the real scheme with deductible costs.
- Trading and professional profits: micro scheme with a flat allowance, or the real scheme.
- Investment income: flat-rate withholding by default, progressive scale by global election.
- Pensions: a 10 % allowance as well, capped on different terms from salaries.
Most households combine three or four categories. Each is computed on its own terms, and the results are then added together to form gross overall income — the starting point of the next module.
Withholding at source is an instalment, not a settlement
Since 2019 employers deduct tax every month. Many people conclude that filing has become optional. It has not: withholding is an instalment computed on a provisional rate, and it never settles the year.
That rate comes from your previous return. By construction it ignores whatever the tax office does not yet know: a marriage, a birth, maintenance paid to a relative, a charitable gift, a change of employer mid-year.
Social levies sit alongside income tax
Definition
Deductible social levy — The portion of the general social contribution that the law lets you subtract from taxable income. The remainder is charged on income that has already been taxed, so the same euros carry two levies.
On a salary, the two social contributions come to 9,7 %, charged on 98,25 % of gross pay. Only 6,8 points of that reduce taxable income. This is precisely why taxable net pay sits above the net pay you received.
Key figures
- Social contributions on salary
- 9,7 % of gross pay
- Base they apply to
- 98,25 % of gross, not the full amount
- Share deductible from taxable income
- 6,8 points out of the 9,7
None of this needs computing on your side: the employer reports taxable net pay with the deductible share already removed. Reading that line matters for a different reason — it lets you check the pre-filled figure on your return and spot a reporting error.
Mistakes to avoid
- Reporting net pay received instead of taxable net pay: a few points of difference distort the whole calculation and make the pre-filled figure impossible to reconcile.
- Treating withholding as a final settlement, when the rate applied comes from last year's return and knows nothing about this year.
- Electing actual expenses without documenting them or comparing them to the 10 % allowance: below the flat rate, the election costs money.
- Forgetting that non-salary income falls into another category with its own rules — the box you tick determines the calculation applied.
Educational content, current with the sources cited. It does not replace advice tailored to your situation. These courses are neither certifying nor CPF-eligible: they prepare for no certification registered with the French RNCP or specific register.