Income tax: when should you detach your student child from your tax household?

 Income tax: when should you detach your student child from your tax household?

Income tax: when should you detach your student child from your tax household?

As soon as the children are adults and continue their studies, the question of whether to detach them from the tax household of the parents arises. When it makes sense to complete their income tax depends on each household.

And this choice should not be studied only under the prism of taxes, but also by examining family allowances and housing allowances. Explanations…

Adult child attached to the tax household of the parents

Attaching your adult child to his tax household is possible without conditions until he is 21 years old. Beyond the age of 21, attachment remains possible if and only if he is pursuing higher education and is under 25 years of age.

By attaching your child to your tax household, you benefit from:

  • An additional half share for the first two children
  • On an additional part for the third child and the following ones
  • A tax reduction of 183 euros per child continuing their studies in higher education

 Your additional half-share, or your additional share, is used to calculate your reference tax income, while benefiting from a higher family quotient. Take the example of a married couple (2 shares) with a student child attached to the tax household (1/2 additional share), the family quotient is 2.5. The reference tax income then takes into account all household income, divided by 2.5. But beware, the tax reduction linked to the family quotient is limited to 1,570 euros per additional half-share.

Adult child detached from the tax household of the parents

Detaching your adult child from the tax household means that you will have to complete your income tax return without him, and that he will have to do the same on his side. If your child is a student, and even if he does extra work to obtain income, there is a very good chance that he will not be taxed.

For your part, you will lose half a share, or even a share if it is the third child or more, but you can deduct in return the child support paid to your child.

You can deduct up to 3,542 euros in pension without supporting documents (food and accommodation costs), and up to 5,959 euros with supporting documents (for example monthly transfers to the account of your adult child).

Impact on family allowances and housing for parents

As soon as you have two or more children, you receive family allowances if at least two of your children under the age of 20 are attached to your tax household. In addition, up to the age of 21 for your dependent child, you can benefit from a flat-rate allowance if he is actually dependent on you.

In concrete terms, this means that a child detached from your tax household causes you to lose the benefit of family allowances totally or partially. It is therefore wise to calculate both the amount of your tax and the new amount of family allowances before making a decision, at least until your student child is 21 years old.

But that’s not all, a child who “leaves” the tax household is also one less child for the calculation of your housing allowances. If you benefit from it, it is therefore in your best interest to carry out a simulation on the CAF or MSA website to find out the amount of your rights in the event of detachment from the tax household.

Impact on housing allowances for children

This data can be very important if your child is studying away from your home. In this case, he will have his own accommodation in a university residence, in a studio or in a shared apartment. The accommodation, whether it is rented furnished or empty, may entitle him to housing allowances.

In concrete terms, if your child is still attached to your tax household, he cannot apply for housing allowances. On the other hand, if he makes his own tax return, he is eligible for these allowances to help him pay his rent.


The moment at which you must detach your child from your tax household depends on the situation of your household on the one hand, and on the situation of your child on the other. Most often, if he continues his studies while staying with you, it is wise to leave him attached to your tax household until he is 21 years old.

On the other hand, when he has to move away from home to continue his studies, it is recommended to detach him from the tax household, especially if he is not housed free of charge. Because receiving housing allowances often offsets the additional amount of income tax to be paid.

However, each case is different. Households taxed with a TMI Marginal Tax Bracket of 41% or 45% will often benefit by paying a tax-deductible pension, while those with low taxes (0% or 11%) will more often have an interest in keeping their child attached.

In order to know the most interesting option for you, we advise you to:

  • Make a simulation on the tax site for income taxes, one with your dependent child, and another without your child with payment of child support
  • Make a simulation on the CAF or MSA website for your own family allowances and accommodation, with or without your dependent student child
  • Make a housing allowance simulation for your child if he lives separately from you
  • Make an activity bonus simulation for your child if he has a student job, even part-time

Take note of the results of each simulation to make the total calculation and choose the most financially attractive solution for you and your child. And redo this calculation each year or whenever there is a change in the situation affecting one of the members of your tax household.