France: Key income tax deadlines and rate updates for September 2026

French taxpayers face several key fiscal deadlines and changes starting in September 2026. On September 1, withholding tax rates are automatically updated based on the 2026 tax declarations regarding 2025 income and charges. This new rate will be reflected in end-of-month salary payments.

Payment deadlines vary depending on the method used. For those not subject to automatic deduction or those paying manually, the deadline is September 15. For online payments, the deadline is extended to September 20.

Regarding the remaining balance for income tax and social security contributions, automatic withdrawals begin on September 25. If the amount owed exceeds 300 euros, the sum will be collected in four installments between September 25 and December 28, 2026. If the amount is 300 euros or less, it will be collected in a single payment on September 25.