Short answer. No. Where the contract was annulled because one party lacked capacity, that party need only restore what he was actually benefited by. A minor who spent or lost the money without gaining anything from it is not obliged to return the full amount, unlike the capacitated party.
What the law says
When the defect of the contract consists in the incapacity of one of the parties, the incapacitated person is not obliged to make any restitution except insofar as he has been benefited by the thing or price received by him.
Civil Code, Article 1399 — Restitution by an Incapacitated Party. Read the full provision →
Annulment normally means giving everything back
When a court annuls a contract, the ordinary consequence is mutual restitution: each side returns what it received, with fruits or interest, so both are put back where they started. Article 1399 of the Civil Code carves out a deliberate exception. When the defect of the contract consists in the incapacity of one of the parties, the incapacitated person is not obliged to make any restitution except insofar as he has been benefited by the thing or price received by him. Incapacity here refers to those the law protects because their consent is legally unreliable — minors, and persons who are insane or otherwise incapable of giving valid consent when they signed.
The rule is a shield, not a licence
The reason for the exception is straightforward. If a minor had to return the full price no matter what became of it, the protection against being bound at all would be worth very little; the person who dealt with him would simply recover everything and lose nothing by having contracted with someone the law says could not properly agree. So the measure is benefit, not the amount received. Note the asymmetry: the capacitated party gets no such relief and must restore what he received in full. The protection also does not turn the transaction into a gift — what the incapacitated party still holds, or what he genuinely gained, remains recoverable.
What counts as being benefited
Benefit is a question of fact and it is decided on evidence rather than on assertion. Money still in hand, or property still in the minor's possession, plainly remains. Where the money was used to pay for something the minor needed — support, schooling, medical care, or paying off his own valid obligation — that use is ordinarily treated as a benefit, because the minor's estate is better off by that amount. Money that was squandered, stolen or lost without leaving anything behind is a different matter. The person claiming restitution bears the practical burden of showing what became of the money and how the incapacitated party gained by it.
What this article does not do
It does not annul anything by itself; it only says what happens after a contract is annulled, and annulment must be sought within the period the law allows or the right is lost. It does not apply where the defect was mistake, fraud, violence, intimidation or undue influence rather than incapacity. It does not cover a minor who actively misrepresented his age, whose position is treated differently. And it says nothing about contracts entered into by a parent or guardian with proper authority, which bind in the usual way. If a transaction involving a minor is in dispute, gather the documents, the birth certificate and the record of where the money went, then consult a lawyer.