Do I have to declare my adult child's income?

Attaching your adult child to your tax home

As soon as a child reaches the age of majority, he or she is in principle taxable personally and has to make his or her own declaration (even if he or she has not received any income). But if it remains at your expense, you can attach it to your tax home, which allows you to enjoy benefits that vary depending on the situation:

• when your adult child is single: increase in the number of shares for calculating your income tax;
• when your child is married, married or in charge of a family: deduction from your income of €6,794 per connected person (your child, his/her spouse if he/she is married or married and each of his/her children);
• when your child is in school: tax reduction (high school: €153; higher education: €183).

How is the attachment request made?

Your child should give you a written request for attachment signed, in which he states that he will not be taxed personally (one application per child). You must keep this document as it may be requested in case of control by the tax administration.

Under what conditions?

Attaching an adult child to your tax return can be done in the following cases:

• your child is under 21 years of age at 1^er January 2024;
• your child is under 25 years of age at 1^er january 2024 and studying at 1^er January 2024 or December 31, 2024.
• your child is disabled (in this case, it can be attached to your tax home regardless of age).

In the case of separate taxation of the parents, an adult child may apply for reunification only to one or other of the tax shelters.

You can use the tax simulator to get an estimate of what you will have to pay, with or without your child's attachment to your tax home.

What should be declared?

If your child is attached to your tax-paying household, you must add to your income the income received by your adult child during the entire year (for the 2025 return, the income received in 2024).

Note that some income does not have to be reported because it is not taxable.

The following shall be exempt from income tax:

• traineeship allowances and wages for apprentices if they do not exceed the annual minimum wage, or €21,273 income received in 2024 (only the excess share is taxable);
• salaries of students up to 25 years of age (student jobs) up to an annual limit of 3 times the monthly minimum wage, i.e. €5,318 income received in 2024 (only the excess share is taxable).

Income from professionalization contracts must be reported.

To learn more about what to report if your adult child is attached to your return, or about what young adults must declare if they make their own declaration, consult our factsheet Income Tax - Report amounts collected by a young person.

Payment of child support

If your child files his or her own return and does not have sufficient incomeHowever, you can opt for another solution: to pay him support that will be deductible from your taxable income.

• If your child does not live at home, the deduction depends on different elements (find the different cases in our practice sheet Income Tax - Child Support Payments).
• If you shelter your child throughout the year, you can deduct a lump sum of €4,039 (without supporting documentation). This amount is doubled (€8,078) if your child is married or passed.

If you are deducting child support, your child has to declare the amount you pay as such.

You must be able to provide proof of your expenses in cash or in kind (payment of rent, food, etc.) and the state of need of your child.