Child support for an adult child in France: how long, and how to deduct it
At 18, support does not stop: it is mostly the tax rules that change.
Checked by Radif Partners · Editorial policy
In France a child’s 18th birthday does not end child support. It remains due while the young adult is not financially self-supporting: studying, training or actively looking for work. The receiving parent must show this regularly, and if the parents disagree the family judge decides; an adult child can even apply to the judge for support themselves. What really changes at 18 is tax. For an adult child who is not attached to the parent’s tax household, the paying parent can no longer deduct all the support: the deduction is capped at €6,855 per child for 2025 income. The young adult, in turn, declares the deducted amount, with a 10% allowance. For families with a child studying abroad or in another French city, these rules apply the same way. The calculator below works out the deduction and what the young adult will declare.
Adult child: support and tax
Deductible over the year
€4,800
| Estimated tax saving (1 share) | €1,440 |
| Cap per adult child | €6,855 |
| Taxable for the child after allowance | €4,320 |
Deduction caps for an adult child (2025 income)
| Situation | Maximum deduction per child |
|---|---|
| Single adult child living elsewhere | €6,855 |
| Married or PACS adult child, in-laws not contributing | €13,710 |
| Child living with you: flat amount, no receipts | €4,075 |
| Child living with you, married or in a PACS: flat amount | €8,151 |
Two conditions apply, according to service-public.fr: the child must not be attached to the tax household of the parent who deducts, and the child’s own income must be too low to cover their needs. Attaching the child and deducting support are therefore alternatives; the better choice depends on the parents’ tax band and the young adult’s income.
Worked examples
| Support per month | Per year | Deductible | Taxable for the child |
|---|---|---|---|
| €200 | €2,400 | €2,400 | €1,946 |
| €400 | €4,800 | €4,800 | €4,320 |
| €600 | €7,200 | €6,855 | €6,170 |
| €800 | €9,600 | €6,855 | €6,170 |
The young adult only declares the part the parent was able to deduct: above the cap, the surplus is neither deductible nor taxable. Detailed rules are on tax deduction and is child support taxable, and the duration of support on how long it lasts.