TLDR: You must declare a change in family status (marriage, PACS, birth) within 60 days of the event. This procedure is mandatory to update the withholding tax rate (taux de prélèvement à la source), but no penalties apply. The declaration is made online via the impots.gouv.fr portal.
Who must declare the change
You must report the change if:
- You get married or enter into a PACS.
- You have a birth or adoption in the family.
You do not need to redeclare a marriage if you were already in a PACS as of January 1 of the year of marriage. If both partners/spouses are subject to the default rate (taux par défaut), the declaration does not automatically modify the withholding rate.
How to declare: methods and required information
The declaration is made online via the tax administration portal. No paper-based methods are available.
Required data for marriage or PACS
- Full personal details of spouses or partners.
- Income declared by each member of the new household in the previous year.
Required data for a birth or adoption
- Child’s first name, last name, date, and place of birth.
- Lien de parenté (relationship to the declarant).
Deadlines and timeframes for declaration
The deadline for reporting the change is 60 days from the event date. If multiple changes occur within 60 days, the deadline starts from the date of the last event. Failure to declare within 60 days is not penalized but prevents requesting a modulation of the withholding tax.
Taxation effects of the change
Update of the withholding tax rate (taux de prélèvement à la source)
The new rate applies:
- Until August 31 of the following year (N+1), unless separate taxation is chosen.
- Until August 31 of the second year (N+2), if separate taxation is selected for the year of the change.
Downward modulation of withholding
To reduce the rate, you must:
- Have declared the change within 60 days.
- Prove that estimated income for the current year (N) differs by more than 5% from the withholding calculated without modulation.
Special case: divorce or separation
In the event of dissolution, withholding is calculated on the declarant’s total annual income, regardless of the actual separation date.